1
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Malkin VM, Fisch NJ. Six-photon resonant scattering of collinear laser pulses in plasma. Phys Rev E 2023; 108:045208. [PMID: 37978720 DOI: 10.1103/physreve.108.045208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 09/25/2023] [Indexed: 11/19/2023]
Abstract
To achieve the highest possible laser intensities with the least laser energy, shorter-wavelengths lasers are advantaged if they can be focused to spots of a few laser wavelengths and durations of several laser periods. However, the top laser pulse energies available nowadays are megajoules at near-optical wavelengths and millijoules at shorter wavelengths. Thus, to produce the highest laser intensities, what is required is an efficient spectral transfer of the huge near-optical energies to shorter wavelengths. It is proposed here that the desired spectral transfer could occur via resonant photon interactions associated with nonlinearity of mildly relativistic motions of plasma electrons in intense laser fields, specifically via the six-photon resonant scattering of collinear laser pulses in plasma. The six-photon interaction can, in fact, be the dominant resonant photon interaction to achieve collinear frequency up-conversion.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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2
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Stollberg C, Kroupp E, Mikitchuk D, Sharma P, Bernshtam V, Cvejić M, Doron R, Stambulchik E, Maron Y, Fruchtman A, Ochs IE, Fisch NJ, Shumlak U. Observation of Fast Current Redistribution in an Imploding Plasma Column. Phys Rev Lett 2023; 130:205101. [PMID: 37267532 DOI: 10.1103/physrevlett.130.205101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 03/10/2023] [Accepted: 05/03/2023] [Indexed: 06/04/2023]
Abstract
Spectroscopic measurements of the magnetic field evolution in a Z-pinch throughout stagnation and with particularly high spatial resolution reveal a sudden current redistribution from the stagnating plasma (SP) to a low-density plasma (LDP) at larger radii, while the SP continues to implode. Based on the plasma parameters it is shown that the current is transferred to an increasing-conductance LDP outside the stagnation, a process likely to be induced by the large impedance of the SP. Since an LDP often exists around imploding plasmas and in various pulsed-power systems, such a fast current redistribution may dramatically affect the behavior and achievable parameters in these systems.
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Affiliation(s)
- C Stollberg
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - E Kroupp
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - D Mikitchuk
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - P Sharma
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - V Bernshtam
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - M Cvejić
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - R Doron
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - E Stambulchik
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - Y Maron
- Weizmann Institute of Science, Herzl Street 243, 7610001 Rehovot, Israel
| | - A Fruchtman
- Department of Physics, Holon Institute of Technology, Holon 58102, Israel
| | - I E Ochs
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - U Shumlak
- Aerospace and Energetics Research Program, University of Washington, Seattle, Washington 98195, USA
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3
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Kolmes EJ, Fisch NJ. Minimum stabilizing energy release for mixing processes. Phys Rev E 2022; 106:055209. [PMID: 36559394 DOI: 10.1103/physreve.106.055209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/04/2022] [Indexed: 11/23/2022]
Abstract
Diffusive operations, which mix the populations of different elements of phase space, can irreversibly transform a given initial state into any of a spectrum of different states from which no further energy can be extracted through diffusive operations. We call these ground states. The lower bound of accessible ground-state energies represents the maximal possible release of energy. This lower bound, sometimes called the diffusively accessible free energy, is of interest in theories of instabilities and wave-particle interactions. On the other hand, the upper bound of accessible ground-state energies has escaped identification as a problem of interest. Yet, as demonstrated here, in the case of a continuous system, it is precisely this upper bound that corresponds to the paradigmatic "quasilinear plateau" ground state of the bump-on-tail distribution. Although for general discrete systems the complexity of calculating the upper bound grows rapidly with the number of states, using techniques adapted from treatments of the lower bound, the upper bound can in fact be computed directly for the three-state discrete system.
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Affiliation(s)
- E J Kolmes
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey, USA
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4
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Malkin VM, Fisch NJ. Super-resonant four-photon collinear laser frequency multiplication in plasma. Phys Rev E 2022; 105:045207. [PMID: 35590623 DOI: 10.1103/physreve.105.045207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 03/31/2022] [Indexed: 06/15/2023]
Abstract
Resonant four-photon scattering could nearly double frequencies of intense laser pulses in plasma. However, transverse slippage between pulses presents a technological challenge, while collinear four-photon scattering is forbidden for classical light dispersion in plasma. Nonlinear renormalization of intense laser pulses can enable collinear four-photon resonance. However, such a very intensity-sensitive resonance is difficult to maintain for evolving pulses. Remarkably, there is a lower-dimensionality submanifold of the resonant four-photon manifold where the evolving pulses stay in resonance. This could enable an all-optical frequency doubling of mildly relativistic-intense laser pulses in collinear geometry, advantageously free of the transverse slippage challenges.
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Affiliation(s)
- V M Malkin
- Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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5
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Cvejić M, Mikitchuk D, Kroupp E, Doron R, Sharma P, Maron Y, Velikovich AL, Fruchtman A, Ochs IE, Kolmes EJ, Fisch NJ. Self-Generated Plasma Rotation in a Z-Pinch Implosion with Preembedded Axial Magnetic Field. Phys Rev Lett 2022; 128:015001. [PMID: 35061496 DOI: 10.1103/physrevlett.128.015001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 10/25/2021] [Accepted: 12/15/2021] [Indexed: 06/14/2023]
Abstract
Using detailed spectroscopic measurements, highly resolved in both time and space, a self-generated plasma rotation is demonstrated using a cylindrical implosion with a preembedded axial magnetic field (B_{z0}). The rotation direction is found to depend on the direction of B_{z0} and its velocity is found comparable to the peak implosion velocity, considerably affecting the force and energy balance throughout the implosion. Moreover, the evolution of the rotation is consistent with magnetic flux surface isorotation, a novel observation in a Z pinch, which is a prototypical time dependent system.
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Affiliation(s)
- M Cvejić
- Weizmann Institute of Science, Rehovot 7610001, Israel
| | - D Mikitchuk
- Weizmann Institute of Science, Rehovot 7610001, Israel
- Ecole polytechnique fèdèrale de Lausanne (EPFL), Route Cantonale, 1015 Lausanne, Switzerland
| | - E Kroupp
- Weizmann Institute of Science, Rehovot 7610001, Israel
| | - R Doron
- Weizmann Institute of Science, Rehovot 7610001, Israel
| | - P Sharma
- Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Y Maron
- Weizmann Institute of Science, Rehovot 7610001, Israel
| | - A L Velikovich
- Plasma Physics Division, Naval Research Laboratory, Washington, D.C. 20375, USA
| | - A Fruchtman
- Holon Institute of Technology, P.O. Box 305, Holon 58102, Israel
| | - I E Ochs
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - E J Kolmes
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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6
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Waybright JC, Mlodik ME, Fisch NJ. Velocity-space compression from Fermi acceleration with Lorentz scattering. Phys Rev E 2022; 105:015207. [PMID: 35193267 DOI: 10.1103/physreve.105.015207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/05/2022] [Indexed: 06/14/2023]
Abstract
The Fermi acceleration model describes how cosmic ray particles accelerate to great speeds by interacting with moving magnetic fields. We identify a variation of the model where light ions interact with a moving wall while undergoing pitch angle scattering through Coulomb collisions due to the presence of a heavier ionic species. The collisions introduce a stochastic component which adds complexity to the particle acceleration profile and sets it apart from collisionless Fermi acceleration models. The unusual effect captured by this simplified variation of Fermi acceleration is the nonconservation of phase space, with the possibility for a distribution of particles initially monotonically decreasing in energy to exhibit an energy peak upon compression. A peaked energy distribution might have interesting applications, such as to optimize fusion reactivity or to characterize astrophysical phenomena that exhibit nonthermal features.
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Affiliation(s)
- J C Waybright
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - M E Mlodik
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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7
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Abstract
In steady state, the fuel cycle of a fusion plasma requires inward particle fluxes of fuel ions. These particle flows are also accompanied by heating. In the case of classical transport in a rotating cylindrical plasma, this heating can proceed through several distinct channels depending on the physical mechanisms involved. Some channels directly heat the fuel ions themselves, whereas others heat electrons. Which channel dominates depends, in general, on the details of the temperature, density and rotation profiles of the plasma constituents. However, remarkably, under relatively few assumptions concerning these profiles, if the α particles, the by-products of the fusion reaction, can be removed directly by other means, then a hot-ion mode tends to emerge naturally.
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Affiliation(s)
- E J Kolmes
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - I E Ochs
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - M E Mlodik
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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8
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Jin S, Reiman AH, Fisch NJ. Coupled heat pulse propagation in two-fluid plasmas. Phys Rev E 2021; 103:053201. [PMID: 34134323 DOI: 10.1103/physreve.103.053201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 04/16/2021] [Indexed: 11/07/2022]
Abstract
Because of the large mass differences between electrons and ions, the heat diffusion in electron-ion plasmas exhibits more complex behavior than simple heat diffusion found in typical gas mixtures. In particular, heat is diffused in two distinct, but coupled, channels. Conventional single fluid models neglect the resulting complexity, and can often inaccurately interpret the results of heat pulse experiments. However, by recognizing the sensitivity of the electron temperature evolution to the ion diffusivity, not only can previous experiments be interpreted correctly, but informative simultaneous measurements can be made of both ion and electron heat channels.
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Affiliation(s)
- S Jin
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544, USA
| | - A H Reiman
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544, USA
| | - N J Fisch
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544, USA
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9
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Abstract
Exact four-photon resonance of collinear planar laser pulses is known to be prohibited by the classical dispersion law of electromagnetic waves in plasma. We show here that the renormalization produced by an arbitrarily small relativistic electron nonlinearity removes this prohibition. The laser frequency shifts in collinear resonant four-photon scattering increase with laser intensities. For laser pulses of frequencies much greater than the electron plasma frequency, the shifts can also be much greater than the plasma frequency and even nearly double the input laser frequency at still small relativistic electron nonlinearities. This may enable broad range tunable lasers of very high frequencies and powers. Since the four-photon scattering does not rely on the Langmuir wave, which is very sensitive to plasma homogeneity, such lasers would also be able to operate at much larger plasma inhomogeneities than lasers based on stimulated Raman scattering in plasma.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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10
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Abstract
The maximum particle kinetic energy that can be extracted from an initial six-dimensional phase space distribution motivates the concept of free or available energy. The free energy depends on the allowed operations that can be performed. A key concept underlying the theoretical treatment of plasmas is the Gardner free energy, where the exchange of the contents of equal phase volumes is allowed. A second free energy concept is the diffusive free energy, in which the contents of volumes are instead averaged. For any finite discretization of phase space, the diffusive free energy is known to be less than the Gardner free energy. However, despite the apparent fundamental differences between these free energies, it is demonstrated here that the Gardner free energy may be recovered from the continuous limit of the diffusive free energy, leading to the surprise that macroscopic phase-space conservation can be achieved by ostensibly entropy-producing microscopic operations.
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Affiliation(s)
- E J Kolmes
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey, USA
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11
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Mlodik ME, Kolmes EJ, Ochs IE, Fisch NJ. Heat pump via charge incompressibility in a collisional magnetized multi-ion plasma. Phys Rev E 2020; 102:013212. [PMID: 32795044 DOI: 10.1103/physreve.102.013212] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 06/28/2020] [Indexed: 11/07/2022]
Abstract
Stratification due to ion-ion friction in a magnetized multiple-ion species plasma is shown to be accompanied by a heat pump effect, transferring heat from one ion species to another as well as from one region of space to another. The heat pump is produced via identified heating mechanisms associated with charge incompressibility and the Ettingshausen effect. Besides their academic interest, these effects may have useful applications to plasma technologies that involve rotation or compression.
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Affiliation(s)
- M E Mlodik
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA, and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - E J Kolmes
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA, and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - I E Ochs
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA, and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA, and Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540, USA
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12
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Malkin VM, Fisch NJ. Towards megajoule x-ray lasers via relativistic four-photon cascade in plasma. Phys Rev E 2020; 101:023211. [PMID: 32168564 DOI: 10.1103/physreve.101.023211] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 02/14/2020] [Indexed: 11/07/2022]
Abstract
A theoretically highly efficient mechanism, operating at high laser intensities and powers, is identified for spectral transferring huge laser energies to shorter ultraviolet and x-ray wavelengths. With megajoule laser energies currently available at near-optical wavelengths, this transfer would, in theory, enable megajoule x-ray lasers, a huge advance over the millijoules x-ray pulses produced now. In fact, enabling even kilojoule x-ray lasers would still be a fantastic advance, and a more likely achievable one, considering practical experimental inefficiencies.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey USA 08540
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey USA 08540
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13
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Reiman AH, Fisch NJ. Suppression of Tearing Modes by Radio Frequency Current Condensation. Phys Rev Lett 2018; 121:225001. [PMID: 30547647 DOI: 10.1103/physrevlett.121.225001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2018] [Revised: 10/19/2018] [Indexed: 06/09/2023]
Abstract
Currents driven by radio frequency (rf) waves in the interior of magnetic islands can stabilize deleterious tearing modes in tokamaks. Present analyses of stabilization assume that the local electron acceleration is unaffected by the presence of the island. However, the power deposition and electron acceleration are sensitive to the perturbation of the temperature. The nonlinear feedback on the power deposition in the island increases the temperature perturbation, and can lead to a bifurcation of the solution to the steady-state heat diffusion equation. The combination of the nonlinearly enhanced temperature perturbation with the rf current drive sensitivity to the temperature leads to an rf current condensation effect, which can increase the efficiency of rf current drive stabilization and reduce its sensitivity to radial misalignment of the ray trajectories. The threshold for the effect is in a regime that has been encountered in experiments, and will likely be encountered in ITER.
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Affiliation(s)
- A H Reiman
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544, USA
| | - N J Fisch
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544, USA
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14
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Abstract
Multiscale turbulence naturally develops and plays an important role in many fluid, gas, and plasma phenomena. Statistical models of multiscale turbulence usually employ Kolmogorov hypotheses of spectral locality of interactions (meaning that interactions primarily occur between pulsations of comparable scales) and scale-invariance of turbulent pulsations. However, optical turbulence described by the nonlinear Schrodinger equation exhibits breaking of both the Kolmogorov locality and scale-invariance. A weaker form of spectral locality that holds for multi-scale optical turbulence enables a derivation of simplified evolution equations that reduce the problem to a single scale modeling. We present the derivation of these equations for Kerr media with random inhomogeneities. Then, we find the analytical solution that exhibits a transition between inverse and direct energy cascades in optical turbulence.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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15
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Kroupp E, Stambulchik E, Starobinets A, Osin D, Fisher VI, Alumot D, Maron Y, Davidovits S, Fisch NJ, Fruchtman A. Turbulent stagnation in a Z-pinch plasma. Phys Rev E 2018; 97:013202. [PMID: 29448437 DOI: 10.1103/physreve.97.013202] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Indexed: 11/07/2022]
Abstract
The ion kinetic energy in a stagnating plasma was previously determined by Kroupp et al. [Phys. Rev. Lett. 107, 105001 (2011)PRLTAO0031-900710.1103/PhysRevLett.107.105001] from Doppler-dominated line shapes augmented by measurements of plasma properties and assuming a uniform-plasma model. Notably, the energy was found to be dominantly stored in hydrodynamic flow. Here we advance a new description of this stagnation as supersonically turbulent. Such turbulence implies a nonuniform density distribution. We demonstrate how to reanalyze the spectroscopic data consistent with the turbulent picture and show that this leads to better concordance of the overconstrained spectroscopic measurements, while also substantially lowering the inferred mean density.
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Affiliation(s)
- E Kroupp
- Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - E Stambulchik
- Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - A Starobinets
- Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - D Osin
- Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - V I Fisher
- Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - D Alumot
- Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Y Maron
- Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - S Davidovits
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - A Fruchtman
- H.I.T.-Holon Institute of Technology, Holon 5810201, Israel
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16
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Hara K, Barth I, Kaminski E, Dodin IY, Fisch NJ. Kinetic simulations of ladder climbing by electron plasma waves. Phys Rev E 2017; 95:053212. [PMID: 28618641 DOI: 10.1103/physreve.95.053212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Indexed: 06/07/2023]
Abstract
The energy of plasma waves can be moved up and down the spectrum using chirped modulations of plasma parameters, which can be driven by external fields. Depending on whether the wave spectrum is discrete (bounded plasma) or continuous (boundless plasma), this phenomenon is called ladder climbing (LC) or autoresonant acceleration of plasmons. It was first proposed by Barth et al. [Phys. Rev. Lett. 115, 075001 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.075001] based on a linear fluid model. In this paper, LC of electron plasma waves is investigated using fully nonlinear Vlasov-Poisson simulations of collisionless bounded plasma. It is shown that, in agreement with the basic theory, plasmons survive substantial transformations of the spectrum and are destroyed only when their wave numbers become large enough to trigger Landau damping. Since nonlinear effects decrease the damping rate, LC is even more efficient when practiced on structures like quasiperiodic Bernstein-Greene-Kruskal (BGK) waves rather than on Langmuir waves per se.
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Affiliation(s)
- Kentaro Hara
- Department of Aerospace Engineering, Texas A&M University, College Station, Texas 77843, USA
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
| | - Ido Barth
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
- Racah Institute of Physics, Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Erez Kaminski
- Birmingham-Southern College, Birmingham, Alabama 35254, USA
| | - I Y Dodin
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
| | - N J Fisch
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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17
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Affiliation(s)
- N. J. Fisch
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
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18
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Abstract
A spinning gas, heated adiabatically through axial compression, is known to exhibit a rotation-dependent heat capacity. However, as equilibrium is approached, an effect is identified here wherein the temperature does not grow homogeneously in the radial direction, but develops a temperature differential with the hottest region on axis, at the maximum of the centrifugal potential energy. This phenomenon, which we call a piezothermal effect, is shown to grow bilinearly with the compression rate and the amplitude of the potential. Numerical simulations confirm a simple model of this effect, which can be generalized to other forms of potential energy and methods of heating.
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Affiliation(s)
- V I Geyko
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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19
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Abstract
Powerful incoherent laser pulses can propagate in focusing Kerr media much longer distances than can coherent pulses, due to the fast phase mixing that prevents transverse filamentation. This distance is limited by 4-wave scattering, which accumulates waves at small transverse wave numbers, where phase mixing is too slow to retain the incoherence and thus prevent the filamentation. However, we identify how this theoretical limit can be overcome by countering this accumulation through transverse heating of the pulse by random fluctuations of the refractive index. Thus, the laser pulse propagation distances are significantly extended, making feasible, in particular, the generation of unprecedentedly intense and powerful short laser pulses in a plasma by means of backward Raman amplification in new random laser regimes.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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20
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Barth I, Dodin IY, Fisch NJ. Ladder Climbing and Autoresonant Acceleration of Plasma Waves. Phys Rev Lett 2015; 115:075001. [PMID: 26317725 DOI: 10.1103/physrevlett.115.075001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Indexed: 06/04/2023]
Abstract
When the background density in a bounded plasma is modulated in time, discrete modes become coupled. Interestingly, for appropriately chosen modulations, the average plasmon energy might be made to grow in a ladderlike manner, achieving upconversion or downconversion of the plasmon energy. This reversible process is identified as a classical analog of the effect known as quantum ladder climbing, so that the efficiency and the rate of this process can be written immediately by analogy to a quantum particle in a box. In the limit of a densely spaced spectrum, ladder climbing transforms into continuous autoresonance; plasmons may then be manipulated by chirped background modulations much like electrons are autoresonantly manipulated by chirped fields. By formulating the wave dynamics within a universal Lagrangian framework, similar ladder climbing and autoresonance effects are predicted to be achievable with general linear waves in both plasma and other media.
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Affiliation(s)
- I Barth
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - I Y Dodin
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - N J Fisch
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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21
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Malkin VM, Toroker Z, Fisch NJ. Exceeding the leading spike intensity and fluence limits in backward Raman amplifiers. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 90:063110. [PMID: 25615208 DOI: 10.1103/physreve.90.063110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2013] [Indexed: 06/04/2023]
Abstract
The leading amplified spike in backward Raman amplifiers can reach nearly relativistic intensities before the saturation by the relativistic electron nonlinearity. The saturation sets an upper limit to the largest achievable leading spike intensity. It is shown here that this limit can be substantially exceeded by the initially subdominant spikes, which surprisingly outgrow the leading spike after its nonlinear saturation. Furthermore, an initially negligible group velocity dispersion of the amplified pulse in strongly undercritical plasma appears to be capable of delaying the longitudinal filamentation instability in the nonlinear saturation regime. This enables further amplification of the pulse to even larger output fluences.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
| | - Z Toroker
- Department of Electrical Engineering, Technion Israel Institute of Technology, Haifa 32000, Israel
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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22
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Geyko VI, Fisch NJ. Enhanced efficiency of internal combustion engines by employing spinning gas. Phys Rev E Stat Nonlin Soft Matter Phys 2014; 90:022139. [PMID: 25215720 DOI: 10.1103/physreve.90.022139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Indexed: 06/03/2023]
Abstract
The efficiency of the internal combustion engine might be enhanced by employing spinning gas. A gas spinning at near sonic velocities has an effectively higher heat capacity, which allows practical fuel cycles, which are far from the Carnot efficiency, to approach more closely the Carnot efficiency. A remarkable gain in fuel efficiency is shown to be theoretically possible for the Otto and Diesel cycles. The use of a flywheel, in principle, could produce even greater increases in efficiency.
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Affiliation(s)
- V I Geyko
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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23
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Affiliation(s)
- N. J. Fisch
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543
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24
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Dodin IY, Schmit PF, Rocks J, Fisch NJ. Negative-mass instability in nonlinear plasma waves. Phys Rev Lett 2013; 110:215006. [PMID: 23745891 DOI: 10.1103/physrevlett.110.215006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Indexed: 06/02/2023]
Abstract
The negative-mass instability, previously found in ion traps, appears as a distinct regime of the sideband instability in nonlinear plasma waves with trapped particles. As the bounce frequency of these particles decreases with the bounce action, bunching can occur if the action distribution is inverted in trapping islands. In contrast to existing theories that also infer instabilities from the anharmonicity of bounce oscillations, spatial periodicity of the islands turns out to be unimportant, and the particle distribution can be unstable even if it is flat at the resonance. An analytical model is proposed that describes both single traps and periodic nonlinear waves and concisely generalizes the conventional description of the sideband instability in plasma waves. The theoretical results are supported by particle-in-cell simulations carried out for a regime accentuating the negative-mass instability.
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Affiliation(s)
- I Y Dodin
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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25
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Abstract
A spinning ideal gas in a cylinder with a smooth surface is shown to have unusual properties. First, under compression parallel to the axis of rotation, the spinning gas exhibits reduced compressibility because energy can be stored in the rotation. Second, the spinning breaks the symmetry under which partial pressures of a mixture of gases simply add proportional to the constituent number densities. Thus, remarkably, in a mixture of spinning gases, an inverse problem can be formulated such that the gas constituents can be determined through external measurements only.
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Affiliation(s)
- V I Geyko
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
| | - N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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26
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Schmit PF, Dodin IY, Rocks J, Fisch NJ. Nonlinear amplification and decay of phase-mixed waves in compressing plasma. Phys Rev Lett 2013; 110:055001. [PMID: 23414024 DOI: 10.1103/physrevlett.110.055001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Indexed: 06/01/2023]
Abstract
Through particle-in-cell simulations, we show that plasma waves carrying trapped electrons can be amplified manyfold via compressing plasma perpendicularly to the wave vector. These simulations are the first ab initio demonstration of the conservation of nonlinear action for such waves, which contains a term independent of the field amplitude. In agreement with the theory, the maximum of amplification gain is determined by the total initial energy of the trapped-particle average motion but otherwise is insensitive to the particle distribution. Further compression destroys the wave; electrons are then untrapped at suprathermal energies and form a residual beam. As compression continues, the bump-on-tail instability is triggered each time one of the discrete modes comes in resonance with this beam. Hence, periodic bursts of the electrostatic energy are produced until a wide quasilinear plateau is formed.
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Affiliation(s)
- P F Schmit
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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27
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Canady J, Shashurin A, Wiley K, Fisch NJ, Keidar M. Characterization of Plasma Parameters and Tissue Injury Produced by Plasma Electrosurgical Systems. Plasma Med 2013. [DOI: 10.1615/plasmamed.2014011979] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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28
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Schmit PF, Fisch NJ. Plasma-based accelerator with magnetic compression. Phys Rev Lett 2012; 109:255003. [PMID: 23368475 DOI: 10.1103/physrevlett.109.255003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Indexed: 06/01/2023]
Abstract
Electron dephasing is a major gain-inhibiting effect in plasma-based accelerators. A novel method is proposed to overcome dephasing, in which the modulation of a modest [~O(10 kG)], axial, uniform magnetic field in the acceleration channel leads to densification of the plasma through magnetic compression, enabling direct, time-resolved control of the plasma wave properties. The methodology is broadly applicable and can be optimized to improve the leading acceleration approaches, including plasma beat wave, plasma wakefield, and laser wakefield acceleration. The advantages of magnetic compression are compared to other proposed techniques to overcome dephasing.
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Affiliation(s)
- P F Schmit
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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29
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Toroker Z, Malkin VM, Fisch NJ. Seed laser chirping for enhanced backward Raman amplification in plasmas. Phys Rev Lett 2012; 109:085003. [PMID: 23002752 DOI: 10.1103/physrevlett.109.085003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Indexed: 06/01/2023]
Abstract
Backward Raman compression in plasma enables pulse compression to intensities not available using material gratings. Mediating the compression with higher density plasma generally produces shorter and therefore more intense output pulses. However, very high density plasma, even if sufficiently tenuous to be transparent to the laser, also produces group velocity dispersion of the amplified pulse, deleteriously affecting the interaction. What is shown here is that, by chirping the seed pulse, the group velocity dispersion may in fact be used advantageously, achieving the maximum intensities over the shortest distances while minimizing unwanted effects.
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Affiliation(s)
- Z Toroker
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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30
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Schmit PF, Fisch NJ. Driving sudden current and voltage in expanding and compressing plasma. Phys Rev Lett 2012; 108:215003. [PMID: 23003272 DOI: 10.1103/physrevlett.108.215003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Revised: 03/13/2012] [Indexed: 06/01/2023]
Abstract
A magnetized plasma preseeded with an initially undamped Langmuir wave is shown to transition suddenly to a collisionless damping regime upon expansion of the plasma perpendicular to the background magnetic field. The resulting anisotropic fast-particle distribution then leads to an electrical current and dc voltage induction. The current drive efficiency of this effect in nonstationary plasmas is shown to depend on the rate of expansion of the plasma, the time-varying collisionality, and the plasma L/R time. Subsequent recompression of the plasma enhances this current drive effect by reducing further the collision rate of the current-carrying electrons.
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Affiliation(s)
- P F Schmit
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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31
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Zhmoginov AI, Fisch NJ. Channeling of fusion alpha-particle power using minority ion catalysis. Phys Rev Lett 2011; 107:175001. [PMID: 22107528 DOI: 10.1103/physrevlett.107.175001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Indexed: 05/31/2023]
Abstract
Maintaining fuel ions hotter than electrons would greatly facilitate controlled nuclear fusion. The parameter range for achieving this temperature disparity is shown here to be enhanced by catalyzing the α-channeling effect (wave-induced simultaneous expulsion and cooling of α particles) through minority-ion heating. Specifically, a wave can extract energy from hot α particles and transfer it to colder minority ions, which act as a catalyst, eventually forwarding the energy to still colder fuel ions through collisions. In comparison with the traditional α-channeling mechanism, the requirements are thereby relaxed on the waves that accomplish the α channeling, which no longer have to interact simultaneously with α particles and fuel ions. Numerical simulations illustrate how the new scheme may increase, for example, the effective fusion reactivity of mirror-confined plasmas.
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Affiliation(s)
- A I Zhmoginov
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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32
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Abstract
A nonlinear dispersion of a general stationary wave in collisionless plasma is obtained in a nondifferential form expressed in terms of a single-particle oscillation-center Hamiltonian. For electrostatic oscillations in nonmagnetized plasma, considered as a paradigmatic example, the linear dielectric function is generalized, and the trapped particle contribution to the wave frequency shift Δω is found analytically as a function of the wave amplitude a. Smooth distributions yield Δω ∼ a(1/2), as usual. However, beamlike distributions of trapped electrons result in different power laws, or even a logarithmic nonlinearity, which are derived as asymptotic limits of the same dispersion relation.
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Affiliation(s)
- I Y Dodin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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33
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Schmit PF, Dodin IY, Fisch NJ. Controlling hot electrons by wave amplification and decay in compressing plasma. Phys Rev Lett 2010; 105:175003. [PMID: 21231053 DOI: 10.1103/physrevlett.105.175003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Indexed: 05/30/2023]
Abstract
Through particle-in-cell simulations, it is demonstrated that a part of the mechanical energy of compressing plasma can be controllably transferred to hot electrons by preseeding the plasma with a Langmuir wave that is compressed together with the medium. Initially, a wave is undamped, so it is amplified under compression due to plasmon conservation. Later, as the phase velocity also changes under compression, Landau damping can be induced at a predetermined instant of time. Then the wave energy is transferred to hot electrons, shaping the particle distribution over a controllable velocity interval, which is wider than that in stationary plasma. For multiple excited modes, the transition between the adiabatic amplification and the damping occurs at different moments; thus, individual modes can deposit their energy independently, each at its own prescribed time.
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Affiliation(s)
- P F Schmit
- Department of Astrophysical Sciences, Princeton University, New Jersey 08544, USA
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34
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Affiliation(s)
- A. I. Zhmoginov
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543
| | - N. J. Fisch
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543
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35
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Zhmoginov AI, Dodin IY, Fisch NJ. Negative effective mass of wave-driven classical particles in dielectric media. Phys Rev E Stat Nonlin Soft Matter Phys 2010; 81:036404. [PMID: 20365879 DOI: 10.1103/physreve.81.036404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 01/28/2010] [Indexed: 05/29/2023]
Abstract
For a classical particle undergoing nonlinear interaction with a wave in dielectric medium, a perturbation theory is developed, showing that the particle motion can be described in terms of an effective parallel mass which can become negative. A relativistic particle interacting with a circularly polarized wave and a static magnetic field is studied as an example. For the three stationary orbits corresponding to the same velocity parallel to the magnetic field, the conditions are found under which all these equilibria are centerlike, or neutrally stable. It is shown that a negative parallel mass is realized in the vicinity of the intermediate-energy equilibrium and can lead to a plasma collective instability.
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Affiliation(s)
- A I Zhmoginov
- Department of Astrophysical Sciences, Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA.
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36
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Malkin VM, Fisch NJ. Quasitransient regimes of backward Raman amplification of intense x-ray pulses. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:046409. [PMID: 19905463 DOI: 10.1103/physreve.80.046409] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2009] [Revised: 08/17/2009] [Indexed: 05/28/2023]
Abstract
New powerful soft x-ray sources may be able to access intensities needed for backward Raman amplification (BRA) of x-ray pulses in plasmas. However, high plasma densities, needed to provide enough coupling between the pump and seed x-ray pulses, cause strong damping of the Langmuir wave that mediates energy transfer from the pump to the seed pulse. Such damping could reduce the coupling, thus making efficient BRA impossible. This work shows that efficient BRA can survive despite the Langmuir wave damping significantly exceeding the linear BRA growth rate. Moreover, the strong Langmuir wave damping can automatically suppress deleterious instabilities of BRA to the thermal noise. The class of "quasitransient" BRA regimes identified here shows that it may be feasible to observe x-ray BRA within available x-ray facilities.
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Affiliation(s)
- V M Malkin
- Princeton University, Princeton, New Jersey 08544, USA
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37
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Geyko VI, Fraiman GM, Dodin IY, Fisch NJ. Ponderomotive acceleration of hot electrons in tenuous plasmas. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 80:036404. [PMID: 19905227 DOI: 10.1103/physreve.80.036404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Indexed: 05/28/2023]
Abstract
The oscillation-center Hamiltonian is derived for a relativistic electron injected with an arbitrary momentum in a linearly polarized laser pulse propagating in tenuous plasma, assuming that the pulse length is smaller than the plasma wavelength. For hot electrons generated by collisions with ions under an intense laser drive, multiple regimes of ponderomotive acceleration are identified, and the laser dispersion is shown to affect the process at plasma densities down to 10(17) cm-3. We consider the regime when the cold plasma is not accelerated, requiring a/gammag<<1, where a is the laser parameter, proportional to the field amplitude, and gammag is the group-velocity Lorentz factor. In this case, the Lorentz factor gamma of hot electrons does not exceed Gamma [triple bond] alpha gammag after acceleration, assuming its initial value also satisfies gamma0 <or=Gamma. Yet gamma approximately Gamma is attained within a wide range of initial conditions; hence, a cutoff in the hot-electron distribution is predicted.
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Affiliation(s)
- V I Geyko
- Institute of Applied Physics, RAS, 46 Ulyanov Street, Nizhny Novgorod 603950, Russia
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38
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Dodin IY, Fisch NJ. Dressed-particle approach in the nonrelativistic classical limit. Phys Rev E Stat Nonlin Soft Matter Phys 2009; 79:026407. [PMID: 19391855 DOI: 10.1103/physreve.79.026407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2008] [Indexed: 05/27/2023]
Abstract
For a nonrelativistic classical particle undergoing arbitrary oscillations in external fields, the generalized effective potential Psi is derived through calculating the nonlinear eigenfrequencies of the particle-field system. Specifically, the ponderomotive potential is extended to a nonlinear oscillator, resulting in multiple branches near the primary resonance. For a pair of particle natural frequencies in a beat resonance, Psi scales linearly with the internal actions and is analogous to the dipole potential for a two-level quantum system. Thus cold quantum particles and highly excited quasiclassical objects permit uniform manipulation tools, particularly, one-way walls.
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Affiliation(s)
- I Y Dodin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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39
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Dodin IY, Fisch NJ. Positive and negative effective mass of classical particles in oscillatory and static fields. Phys Rev E Stat Nonlin Soft Matter Phys 2008; 77:036402. [PMID: 18517528 DOI: 10.1103/physreve.77.036402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Indexed: 05/26/2023]
Abstract
A classical particle oscillating in an arbitrary high-frequency or static field effectively exhibits a modified rest mass m(eff) derived from the particle averaged Lagrangian. Relativistic ponderomotive and diamagnetic forces, as well as magnetic drifts, are obtained from the m(eff) dependence on the guiding center location and velocity. The effective mass is not necessarily positive and can result in backward acceleration when an additional perturbation force is applied. As an example, adiabatic dynamics with m||>0 and m||<0 is demonstrated for a wave-driven particle along a dc magnetic field, m|| being the effective longitudinal mass derived from m(eff). Multiple energy states are realized in this case, yielding up to three branches of m|| for a given magnetic moment and parallel velocity.
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Affiliation(s)
- I Y Dodin
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
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40
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Malkin VM, Fisch NJ. Relic crystal-lattice effects on Raman compression of powerful x-ray pulses in plasmas. Phys Rev Lett 2007; 99:205001. [PMID: 18233147 DOI: 10.1103/physrevlett.99.205001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Indexed: 05/25/2023]
Abstract
Powerful x-ray pulses might be compressed to even greater powers by means of backward Raman amplification in ultradense plasmas produced by ionizing condensed matter by the same pulses. The pulse durations contemplated are shorter than the time for complete smoothing of the crystal lattice by thermal motion of ions. Although inhomogeneities are generally thought to be deleterious to the Raman amplification, the relic lattice might, in fact, be useful for the Raman amplification. The x-ray frequency band gaps can suppress parasitic Raman scattering of amplified pulses, while enhanced dispersion of the x-ray group velocity near the gaps can delay self-phase-modulation instability, thereby enabling further amplification of the x rays.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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41
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Dodin IY, Fisch NJ. Stochastic extraction of periodic attosecond bunches from relativistic electron beams. Phys Rev Lett 2007; 98:234801. [PMID: 17677909 DOI: 10.1103/physrevlett.98.234801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Indexed: 05/16/2023]
Abstract
Intense laser waves can form a time-dependent gate, which transmits or reflects particles depending on their initial phases. When faced by a relativistic electron beam, such a barrier slices it by randomly scattering all but some particles, which nearly conserve their velocity. Subfemtosecond or attosecond periodic electron bunches are then formed downstream and can be used, for example, to generate coherent x rays via Thomson backscattering of the laser light.
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Affiliation(s)
- I Y Dodin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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42
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Abstract
Localized regions of intense large-scale radiofrequency field are known to act like effective ("ponderomotive") potential barriers, which scatter particles elastically and in the direction determined by the particle initial velocity rather than phase. In smaller-scale fields, transmission through a ponderomotive barrier is probabilistic and resembles tunneling of a quantum particle through a static potential. We derive asymptotic expressions for the phase-averaged transmission coefficient T as a function of the particle energy E0. We show that, unlike for a truly quantum particle, T(E0) is of algebraic form and has a threshold, below which transmission does not occur. We also find a threshold in E0, above which all particles are transmitted regardless of their initial phase.
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Affiliation(s)
- I Y Dodin
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
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43
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Malkin VM, Fisch NJ, Wurtele JS. Compression of powerful x-ray pulses to attosecond durations by stimulated Raman backscattering in plasmas. Phys Rev E Stat Nonlin Soft Matter Phys 2007; 75:026404. [PMID: 17358429 DOI: 10.1103/physreve.75.026404] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Indexed: 05/14/2023]
Abstract
Backward Raman amplification (BRA) in plasmas holds the potential for longitudinal compression and focusing of powerful x-ray pulses. In principle, this method is capable of producing pulse intensities close to the vacuum breakdown threshold by manipulating the output of planned x-ray sources. The minimum wavelength limit of BRA applicability to compression of laser pulses in plasmas is found.
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Affiliation(s)
- V M Malkin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
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44
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Abstract
The injection of radio frequency waves can cool charged particles trapped in a magnetic mirror. This cooling effect relies upon waves with azimuthal and axial phase velocities resonating with ions in different axial locations. The ions are then forced to diffuse along highly constrained orbits, such that they can only exit the magnetic trap at low energy. This cooling effect may have application to magnetic fusion mirror machines, where the free energy of the fusion by-products, the alpha particles, might be channeled into the waves that effect the cooling, thereby both extracting the fusion ash quickly and making that energy available in a convenient form for more useful purposes.
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Affiliation(s)
- N J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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45
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Abstract
In a degenerate plasma, the rates of electron processes are much smaller than the classical model would predict, affecting the efficiencies of current generation by external noninductive means, such as by electromagnetic radiation or intense ion beams. For electron-based mechanisms, the current-drive efficiency is higher than the classical prediction by more than a factor of 6 in a degenerate hydrogen plasma, mainly because the electron-electron collisions do not quickly slow down fast electrons. Moreover, electrons much faster than thermal speeds are more readily excited without exciting thermal electrons. In ion-based mechanisms of current drive, the efficiency is likewise enhanced due to the degeneracy effects, since the electron stopping power on slow ion beams is significantly reduced.
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Affiliation(s)
- S Son
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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46
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Dodin IY, Fisch NJ. Ponderomotive ratchet in a uniform magnetic field. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 72:046602. [PMID: 16383549 DOI: 10.1103/physreve.72.046602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 07/21/2005] [Indexed: 05/05/2023]
Abstract
We show how a ratchet effect, generally used in systems with periodic potentials, can also be practiced on charged particles by an ac field alone, in a background magnetic field near the cyclotron resonance. The effect relies entirely on the spatial inhomogeneity of the high-frequency drive, which produces a deterministic asymmetric ponderomotive barrier for undamped particles. Such a barrier can reflect particles incident from one side while transmitting those incident from the opposite side, hence acting somewhat like a Maxwell demon. The necessary fields are perhaps most easily realized in a plasma, though the effect is more general.
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Affiliation(s)
- I Y Dodin
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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47
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Abstract
The average dynamics of a classical particle under the action of a high-frequency radiation resembles quantum particle motion in a conservative field with an effective de Broglie wavelength lambda equal to the particle average displacement on the oscillation period. In a quasiclassical field, with a spatial scale large compared to lambda, the guiding-center motion is adiabatic. Otherwise, a particle exhibits quantized eigenstates in ponderomotive potential wells, tunnels through "classically forbidden" regions, and experiences stochastic reflection from attractive potentials.
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Affiliation(s)
- I Y Dodin
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA
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48
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Balakin AA, Fraiman GM, Fisch NJ, Suckewer S. Backward Raman amplification in a partially ionized gas. Phys Rev E Stat Nonlin Soft Matter Phys 2005; 72:036401. [PMID: 16241573 DOI: 10.1103/physreve.72.036401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Indexed: 05/05/2023]
Abstract
Compressing laser pulses to extremely high intensities through backward Raman amplification might be accomplished in a plasma medium. While the theory is relatively straightforward for homogeneous fully ionized plasma, a number of important effects enter when the plasma is not fully ionized. In particular, when a mixture of gases is employed to accomplish the coupling, there can be several thresholds for incremental ionization. The refraction of both the pump and the seed is then strongly affected by the plasma ionization. Moreover, in the case of Raman backscattering in partially ionized plasma, the degree of plasma ionization is particularly sensitive to the counterpropagating geometry. This idea is examined in light of data for a recent experiment on a Raman amplifier.
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Affiliation(s)
- A A Balakin
- Institute of Applied Physics, RAS, Nizhnii Novgorod, Russia 603950
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Raizen MG, Dudarev AM, Niu Q, Fisch NJ. Compression of atomic phase space using an asymmetric one-way barrier. Phys Rev Lett 2005; 94:053003. [PMID: 15783635 DOI: 10.1103/physrevlett.94.053003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Indexed: 05/24/2023]
Abstract
We show how to construct asymmetric optical barriers for atoms. These barriers can be used to compress phase-space of a sample by creating a confined region in space where atoms can accumulate with heating at the single photon recoil level. We illustrate our method with a simple two-level model and then show how it can be applied to more realistic multilevel atoms.
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Affiliation(s)
- M G Raizen
- Department of Physics, The University of Texas, Austin, Texas 78712-1081, USA
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Cheng W, Avitzour Y, Ping Y, Suckewer S, Fisch NJ, Hur MS, Wurtele JS. Reaching the nonlinear regime of Raman amplification of ultrashort laser pulses. Phys Rev Lett 2005; 94:045003. [PMID: 15783565 DOI: 10.1103/physrevlett.94.045003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Indexed: 05/24/2023]
Abstract
The intensity of a subpicosecond laser pulse was amplified by a factor of up to 1000 using the Raman backscatter interaction in a 2 mm long gas jet plasma. The process of Raman amplification reached the nonlinear regime, with the intensity of the amplified pulse exceeding that of the pump pulse by more than an order of magnitude. Features unique to the nonlinear regime such as gain saturation, bandwidth broadening, and pulse shortening were observed. Simulation and theory are in qualitative agreement with the measurements.
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Affiliation(s)
- W Cheng
- Department of MAE, School of Engineering and Applied Science, Princeton University, Princeton, New Jersey 08544, USA
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