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Sprenkle RT, Silvestri LG, Murillo MS, Bergeson SD. Temperature relaxation in strongly-coupled binary ionic mixtures. Nat Commun 2022; 13:15. [PMID: 35013203 PMCID: PMC8748956 DOI: 10.1038/s41467-021-27696-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 12/02/2021] [Indexed: 11/09/2022] Open
Abstract
New facilities such as the National Ignition Facility and the Linac Coherent Light Source have pushed the frontiers of high energy-density matter. These facilities offer unprecedented opportunities for exploring extreme states of matter, ranging from cryogenic solid-state systems to hot, dense plasmas, with applications to inertial-confinement fusion and astrophysics. However, significant gaps in our understanding of material properties in these rapidly evolving systems still persist. In particular, non-equilibrium transport properties of strongly-coupled Coulomb systems remain an open question. Here, we study ion-ion temperature relaxation in a binary mixture, exploiting a recently-developed dual-species ultracold neutral plasma. We compare measured relaxation rates with atomistic simulations and a range of popular theories. Our work validates the assumptions and capabilities of the simulations and invalidates theoretical models in this regime. This work illustrates an approach for precision determinations of detailed material properties in Coulomb mixtures across a wide range of conditions.
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Affiliation(s)
- R Tucker Sprenkle
- Department of Physics and Astronomy, Brigham Young University, Provo, UT, 84602, USA
- Honeywell Quantum Solutions, 303 S Technology Ct, Broomfield, CO, 80021, USA
| | - L G Silvestri
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA
| | - M S Murillo
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, MI, 48824, USA.
| | - S D Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, UT, 84602, USA.
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2
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Dharodi VS, Murillo MS. Sculpted ultracold neutral plasmas. Phys Rev E 2020; 101:023207. [PMID: 32168665 DOI: 10.1103/physreve.101.023207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Ultracold neutral plasma (UNP) experiments allow for careful control of plasma properties across Coulomb coupling regimes. Here, we examine how UNPs can be used to study heterogeneous, nonequilibrium phenomena, including nonlinear waves, transport, hydrodynamics, kinetics, stopping power, and instabilities. Through a series of molecular dynamics simulations, we have explored UNPs formed with spatially modulated ionizing radiation. We have developed a computational model for such sculpted UNPs that includes an ionic screened Coulomb interaction with a spatiotemporal screening length, and Langevin-based spatial ion-electron and ion-neutral collisions. We have also developed a hydrodynamics model and have extracted its field quantities (density, flow velocity, and temperature) from the molecular dynamics simulation data, allowing us to investigate kinetics by examining moment ratios and phase-space dynamics; we find that it is possible to create UNPs that vary from nearly perfect fluids (Euler limit) to highly kinetic plasmas. We have examined plasmas in three geometries: a solid rod, a hollow rod, and a gapped slab; we have studied basic properties of these plasmas, including the spatial Coulomb coupling parameter. By varying the initial conditions, we find that we can design experimental plasmas that would allow the exploration of a wide range of phenomena, including shock and blast waves, stopping power, two-stream instabilities, and much more. Using an evaporative cooling geometry, our results suggest that much larger Coulomb couplings can be achieved, possibly in excess of 10.
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Affiliation(s)
- Vikram S Dharodi
- Department of Computational Mathematics, Science, and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
| | - Michael S Murillo
- Department of Computational Mathematics, Science, and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
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3
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Choi Y, Dharuman G, Murillo MS. High-frequency response of classical strongly coupled plasmas. Phys Rev E 2019; 100:013206. [PMID: 31499843 DOI: 10.1103/physreve.100.013206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Indexed: 06/10/2023]
Abstract
The dynamic structure factor (DSF) of the Yukawa system is here obtained with highly converged molecular dynamics (MD) over the entire liquid phase. The data provide a rigorous test of theoretical models of ion-acoustic wave-dispersion relations, the intermediate scattering function, and the high-frequency response. We compare our MD results with seven diverse models, finding good agreement among those that enforce the three basic sum rules for dispersion properties, although one of the models has previously unreported spurious peaks. The MD simulations reveal that at intermediate frequencies ω, the high-frequency response of the DSF follows a power law, going approximately as ω^{-p}, where p>0, and p shows nontrivial dependencies on the wave vector q and the plasma parameters κ and Γ. In contrast, among the seven comparison models, the predicted high-frequency response is found to be independent of {q,κ,Γ}. This high-frequency power suggests a useful fitting form. In addition, these results expose limitations of several models and, moreover, suggest that some approaches are difficult or impossible to extend because of the lack of finite moments. We also find the double-plasmon resonance peak in our MD simulations that none of the theoretical models predicts.
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Affiliation(s)
- Yongjun Choi
- Institute for Cyber-Enabled Research, Michigan State University, East Lansing, Michigan 48824, USA
| | - Gautham Dharuman
- Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
| | - Michael S Murillo
- Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
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4
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Bergeson S. Really cool neutral plasmas. Science 2019; 363:33-34. [DOI: 10.1126/science.aau7988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Properties of laser-cooled neutral plasmas can be used to model high–energy-density plasmas
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Affiliation(s)
- Scott Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, UT 84602, USA
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Lyon M, Rolston SL. Ultracold neutral plasmas. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:017001. [PMID: 27852983 DOI: 10.1088/0034-4885/80/1/017001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
By photoionizing samples of laser-cooled atoms with laser light tuned just above the ionization limit, plasmas can be created with electron and ion temperatures below 10 K. These ultracold neutral plasmas have extended the temperature bounds of plasma physics by two orders of magnitude. Table-top experiments, using many of the tools from atomic physics, allow for the study of plasma phenomena in this new regime with independent control over the density and temperature of the plasma through the excitation process. Characteristic of these systems is an inhomogeneous density profile, inherited from the density distribution of the laser-cooled neutral atom sample. Most work has dealt with unconfined plasmas in vacuum, which expand outward at velocities of order 100 m/s, governed by electron pressure, and with lifetimes of order 100 μs, limited by stray electric fields. Using detection of charged particles and optical detection techniques, a wide variety of properties and phenomena have been observed, including expansion dynamics, collective excitations in both the electrons and ions, and collisional properties. Through three-body recombination collisions, the plasmas rapidly form Rydberg atoms, and clouds of cold Rydberg atoms have been observed to spontaneously avalanche ionize to form plasmas. Of particular interest is the possibility of the formation of strongly coupled plasmas, where Coulomb forces dominate thermal motion and correlations become important. The strongest impediment to strong coupling is disorder-induced heating, a process in which Coulomb energy from an initially disordered sample is converted into thermal energy. This restricts electrons to a weakly coupled regime and leaves the ions barely within the strongly coupled regime. This review will give an overview of the field of ultracold neutral plasmas, from its inception in 1999 to current work, including efforts to increase strong coupling and effects on plasma properties due to strong coupling.
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Affiliation(s)
- M Lyon
- Joint Quantum Institute, University of Maryland, College Park and NIST, College Park, MD 20742, USA
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7
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Langin TK, Strickler T, Maksimovic N, McQuillen P, Pohl T, Vrinceanu D, Killian TC. Demonstrating universal scaling for dynamics of Yukawa one-component plasmas after an interaction quench. Phys Rev E 2016; 93:023201. [PMID: 26986426 DOI: 10.1103/physreve.93.023201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Indexed: 06/05/2023]
Abstract
The Yukawa one-component plasma (OCP) model is a paradigm for describing plasmas that contain one component of interest and one or more other components that can be treated as a neutralizing, screening background. In appropriately scaled units, interactions are characterized entirely by a screening parameter, κ. As a result, systems of similar κ show the same dynamics, regardless of the underlying parameters (e.g., density and temperature). We demonstrate this behavior using ultracold neutral plasmas (UNPs) created by photoionizing a cold (T≤10 mK) gas. The ions in UNP systems are well described by the Yukawa model, with the electrons providing the screening. Creation of the plasma through photoionization can be thought of as a rapid quench of the interaction potential from κ=∞ to a final κ value set by the electron density and temperature. We demonstrate experimentally that the postquench dynamics are universal in κ over a factor of 30 in density and an order of magnitude in temperature. Results are compared with molecular-dynamics simulations. We also demonstrate that features of the postquench kinetic energy evolution, such as disorder-induced heating and kinetic-energy oscillations, can be used to determine the plasma density and the electron temperature.
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Affiliation(s)
- T K Langin
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - T Strickler
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - N Maksimovic
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - P McQuillen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
| | - T Pohl
- Max Planck Institute for Complex Systems, Dresden, Germany
| | - D Vrinceanu
- Department of Physics, Texas Southern University, Houston, Texas 77004, USA
| | - T C Killian
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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8
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Strongly-coupled plasmas formed from laser-heated solids. Sci Rep 2015; 5:15693. [PMID: 26503293 PMCID: PMC4621604 DOI: 10.1038/srep15693] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 10/01/2015] [Indexed: 11/09/2022] Open
Abstract
We present an analysis of ion temperatures in laser-produced plasmas formed from solids with different initial lattice structures. We show that the equilibrium ion temperature is limited by a mismatch between the initial crystallographic configuration and the close-packed configuration of a strongly-coupled plasma, similar to experiments in ultracold neutral plasmas. We propose experiments to demonstrate and exploit this crystallographic heating in order to produce a strongly coupled plasma with a coupling parameter of several hundred.
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Lyon M, Bergeson SD, Diaw A, Murillo MS. Using higher ionization states to increase Coulomb coupling in an ultracold neutral plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:033101. [PMID: 25871218 DOI: 10.1103/physreve.91.033101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Indexed: 06/04/2023]
Abstract
We report measurements and simulations of the time-evolving rms velocity distribution in an ultracold neutral plasma. A strongly coupled ultracold neutral Ca+ plasma is generated by photoionizing laser-cooled atoms close to threshold. A fraction of these ions is then promoted to the second ionization state to form a mixed Ca+-Ca2+ plasma. By varying the time delay between the first and the second ionization events, a minimum in ion heating is achieved. We show that the Coulomb strong-coupling parameter Γ increases by a factor of 1.4 to a maximum value of 3.6. A pure Ca2+ plasma would have Γ=6.8, moving these strongly coupled systems closer to the regime of liquid-like correlations.
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Affiliation(s)
- M Lyon
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - S D Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - A Diaw
- New Mexico Consortium, Los Alamos, New Mexico 87544, USA
| | - M S Murillo
- New Mexico Consortium, Los Alamos, New Mexico 87544, USA
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10
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Bannasch G, Killian TC, Pohl T. Strongly coupled plasmas via Rydberg blockade of cold atoms. PHYSICAL REVIEW LETTERS 2013; 110:253003. [PMID: 23829735 DOI: 10.1103/physrevlett.110.253003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Indexed: 06/02/2023]
Abstract
We propose and analyze a new scheme to produce ultracold neutral plasmas deep in the strongly coupled regime. The method exploits the interaction blockade between cold atoms excited to high-lying Rydberg states and therefore does not require substantial extensions of current ultracold plasma experiments. Extensive simulations reveal a universal behavior of the resulting Coulomb coupling parameter, providing a direct connection between the physics of strongly correlated Rydberg gases and ultracold plasmas. The approach is shown to reduce currently accessible temperatures by more than an order of magnitude, which opens up a new regime for ultracold plasma research and cold ion-beam applications with readily available experimental techniques.
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Affiliation(s)
- G Bannasch
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
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11
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Bannasch G, Castro J, McQuillen P, Pohl T, Killian TC. Velocity relaxation in a strongly coupled plasma. PHYSICAL REVIEW LETTERS 2012; 109:185008. [PMID: 23215292 DOI: 10.1103/physrevlett.109.185008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Indexed: 06/01/2023]
Abstract
Collisional relaxation of Coulomb systems is studied in the strongly coupled regime. We use an optical pump-probe approach to manipulate and monitor the dynamics of ions in an ultracold neutral plasma, which allows direct measurement of relaxation rates in a regime where common Landau-Spitzer theory breaks down. Numerical simulations confirm the experimental results and display non-Markovian dynamics at early times.
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Affiliation(s)
- G Bannasch
- Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany
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12
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Heilmann N, Peatross JB, Bergeson SD. "Ultracold" neutral plasmas at room temperature. PHYSICAL REVIEW LETTERS 2012; 109:035002. [PMID: 22861862 DOI: 10.1103/physrevlett.109.035002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Indexed: 06/01/2023]
Abstract
We report a measurement of the electron temperature in a plasma generated by a high-intensity laser focused into a jet of neon. The 15 eV electron temperature is determined using an analytic solution of the plasma equations assuming local thermodynamic equilibrium, initially developed for ultracold neutral plasmas. We show that this analysis method accurately reproduces more sophisticated plasma simulations in our temperature and density range. While our plasma temperatures are far outside the typical "ultracold" regime, the ion temperature is determined by the plasma density through disorder-induced heating just as in ultracold neutral plasma experiments. Based on our results, we outline a pathway for achieving a strongly coupled neutral laser-produced plasma that even more closely resembles ultracold neutral plasma conditions.
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Affiliation(s)
- N Heilmann
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
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13
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Castro J, McQuillen P, Killian TC. Ion acoustic waves in ultracold neutral plasmas. PHYSICAL REVIEW LETTERS 2010; 105:065004. [PMID: 20867986 DOI: 10.1103/physrevlett.105.065004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Indexed: 05/29/2023]
Abstract
We photoionize laser-cooled atoms with a laser beam possessing spatially periodic intensity modulations to create ultracold neutral plasmas with controlled density perturbations. Laser-induced fluorescence imaging reveals that the density perturbations oscillate in space and time, and the dispersion relation of the oscillations matches that of ion acoustic waves, which are long-wavelength, electrostatic, density waves.
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Affiliation(s)
- J Castro
- Department of Physics and Astronomy and Rice Quantum Institute, Rice University, Houston, Texas 77005, USA
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14
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Castro J, McQuillen P, Gao H, Killian TC. The role of collisions and strong coupling in ultracold plasmas. ACTA ACUST UNITED AC 2009. [DOI: 10.1088/1742-6596/194/1/012065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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15
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Gavriliuk AP, Isaev IL, Karpov SV, Krasnov IV, Shaparev NY. Brownian dynamic of laser cooling and crystallization of electron-ion plasma. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009; 80:056404. [PMID: 20365080 DOI: 10.1103/physreve.80.056404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Indexed: 05/29/2023]
Abstract
Laser cooling and crystallization of electron-ion plasma is studied using the Brownian dynamics simulation technique and taking into consideration the interaction of ions with the electron subsystem. It has been shown that the nonlinear dependence of laser friction force on the velocity of ions has to be taken into account in order to simulate in an adequate manner the cooling dynamics and obtain a correct estimate for minimum temperatures. It has been found that times required for formation of an ordered ionic structure can be much longer than the typical plasma cooling time.
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Affiliation(s)
- A P Gavriliuk
- Institute of Computational Modeling, Russian Academy of Sciences, Krasnoyarsk, Russia
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16
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van der Geer SB, de Loos MJ, Vredenbregt EJD, Luiten OJ. Ultracold electron source for single-shot, ultrafast electron diffraction. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2009; 15:282-9. [PMID: 19575829 DOI: 10.1017/s143192760909076x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Ultrafast electron diffraction (UED) enables studies of structural dynamics at atomic length and timescales, i.e., 0.1 nm and 0.1 ps, in single-shot mode. At present UED experiments are based on femtosecond laser photoemission from solid state cathodes. These photoemission sources perform excellently, but are not sufficiently bright for single-shot studies of, for example, biomolecular samples. We propose a new type of electron source, based on near-threshold photoionization of a laser-cooled and trapped atomic gas. The electron temperature of these sources can be as low as 10 K, implying an increase in brightness by orders of magnitude. We investigate a setup consisting of an ultracold electron source and standard radio-frequency acceleration techniques by GPT tracking simulations. The simulations use realistic fields and include all pairwise Coulomb interactions. We show that in this setup 120 keV, 0.1 pC electron bunches can be produced with a longitudinal emittance sufficiently small for enabling sub-100 fs bunch lengths at 1% relative energy spread. A transverse root-mean-square normalized emittance of epsilon(x) = 10 nm is obtained, significantly better than from photoemission sources. Correlations in transverse phase-space indicate that the transverse emittance can be improved even further, enabling single-shot studies of biomolecular samples.
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Affiliation(s)
- S B van der Geer
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
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17
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Dharma-Wardana MWC. Quantum corrections and bound-state effects in the energy relaxation of hot dense hydrogen. PHYSICAL REVIEW LETTERS 2008; 101:035002. [PMID: 18764259 DOI: 10.1103/physrevlett.101.035002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2008] [Indexed: 05/26/2023]
Abstract
Simple analytic formulas for energy relaxation (ER) in electron-ion systems, with quantum corrections, ion dynamics, and RPA-type screening are presented. ER in the presence of bound electrons is examined in view of recent simulations for ER in hydrogen in the range 10{20}-10{24} electrons/cc.
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Murillo MS, Dharma-wardana MWC. Temperature relaxation in hot dense hydrogen. PHYSICAL REVIEW LETTERS 2008; 100:205005. [PMID: 18518546 DOI: 10.1103/physrevlett.100.205005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Indexed: 05/26/2023]
Abstract
Temperature equilibration of hydrogen is studied for conditions relevant to inertial confinement fusion. New molecular-dynamics simulations and results from quantum many-body theory are compared with Landau-Spitzer predictions for temperatures T with 50<T<4000 eV and densities with Wigner-Seitz radii rs=1.0 and 0.5. The relaxation is slower than the Landau-Spitzer result, even for T in the kilo-electron-volt range, but converge to agreement in the high-T limit.
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Affiliation(s)
- Michael S Murillo
- Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
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20
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Laha S, Gupta P, Simien CE, Gao H, Castro J, Pohl T, Killian TC. Experimental realization of an exact solution to the Vlasov equations for an expanding plasma. PHYSICAL REVIEW LETTERS 2007; 99:155001. [PMID: 17995174 DOI: 10.1103/physrevlett.99.155001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2007] [Indexed: 05/25/2023]
Abstract
We study the expansion of ultracold neutral plasmas in the regime in which inelastic collisions are negligible. The plasma expands due to the thermal pressure of the electrons, and for an initial spherically symmetric Gaussian density profile, the expansion is self-similar. Measurements of the plasma size and ion kinetic energy using fluorescence imaging and spectroscopy show that the expansion follows an analytic solution of the Vlasov equations for an adiabatically expanding plasma.
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Affiliation(s)
- S Laha
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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21
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Murillo MS. Ultrafast dynamics of strongly coupled plasmas. PHYSICAL REVIEW LETTERS 2006; 96:165001. [PMID: 16712240 DOI: 10.1103/physrevlett.96.165001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2006] [Indexed: 05/09/2023]
Abstract
The ultrafast dynamics of a strongly coupled plasma following an energy landscape shift is studied theoretically and with simulation. To lowest order in time, the inertial dynamics on the new landscape can be characterized by the plasma microfield, which, for the randomly ordered case of an ultracold neutral plasma, is dominated by nearest neighbor interactions. Formation of the pair correlation function arises after ballistic overshoot, which leads to oscillations in the effective temperature. Warm dense matter systems are also considered in this context.
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Affiliation(s)
- Michael S Murillo
- Department of Physics, University of California, Berkeley, California 94720, USA
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22
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Cummings EA, Daily JE, Durfee DS, Bergeson SD. Fluorescence measurements of expanding strongly coupled neutral plasmas. PHYSICAL REVIEW LETTERS 2005; 95:235001. [PMID: 16384310 DOI: 10.1103/physrevlett.95.235001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2005] [Indexed: 05/05/2023]
Abstract
We report new detailed density profile measurements in expanding strongly coupled neutral calcium plasmas. Using laser-induced fluorescence techniques, we determine plasma densities in the range of 10(5) to 10(9) cm(-3) to with a time resolution limit as small as 7 ns. Strong coupling in the plasma ions is inferred directly from the fluorescence signals. Evidence for strong coupling at late times is presented, confirming a recent theoretical result.
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Affiliation(s)
- E A Cummings
- Brigham Young University, Department of Physics and Astronomy, Provo, Utah 84602, USA
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Pohl T, Pattard T, Rost JM. Relaxation to nonequilibrium in expanding ultracold neutral plasmas. PHYSICAL REVIEW LETTERS 2005; 94:205003. [PMID: 16090258 DOI: 10.1103/physrevlett.94.205003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Indexed: 05/03/2023]
Abstract
We investigate the strongly correlated ion dynamics and the degree of coupling achievable in the evolution of freely expanding ultracold neutral plasmas. We demonstrate that the ionic Coulomb coupling parameter Gamma(i) increases considerably in later stages of the expansion, reaching the strongly coupled regime despite the well known initial drop of Gamma(i) to order unity due to disorder-induced heating. Furthermore, we formulate a suitable measure of correlation and show that Gamma(i) calculated from the ionic temperature and density reflects the degree of order in the system if it is sufficiently close to a quasisteady state. At later times, however, the expansion of the plasma cloud becomes faster than the relaxation of correlations, and the system does not reach thermodynamic equilibrium anymore.
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Affiliation(s)
- T Pohl
- Max Planck Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, D-01187 Dresden, Germany
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24
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Cornolti F, Ceccherini F, Betti S, Pegoraro F. Charged state of a spherical plasma in vacuum. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2005; 71:056407. [PMID: 16089660 DOI: 10.1103/physreve.71.056407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Indexed: 05/03/2023]
Abstract
The stationary state of a spherically symmetric plasma configuration is investigated in the limit of immobile ions and weak collisions. Configurations with small radii are positively charged as a significant fraction of the electron population evaporates during the equilibration process, leaving behind an electron distribution function with an energy cutoff. Such charged plasma configurations are of interest for the study of Coulomb explosions and ion acceleration from small clusters irradiated by ultraintense laser pulses and for the investigation of ion bunches propagation in a plasma.
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Affiliation(s)
- F Cornolti
- Dipartimento di Fisica Enrico Fermi, INFM & CNISM, Università di Pisa, Largo B. Pontecorvo 3, 56127 Pisa, Italy
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