1
|
Milder AL, Zielinski J, Katz J, Rozmus W, Edgell D, Hansen A, Sherlock M, Bruulsema C, Palastro JP, Turnbull D, Froula DH. Direct Measurement of the Return Current Instability in a Laser-Produced Plasma. Phys Rev Lett 2022; 129:115002. [PMID: 36154407 DOI: 10.1103/physrevlett.129.115002] [Citation(s) in RCA: 1] [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: 06/22/2022] [Revised: 07/22/2022] [Accepted: 08/11/2022] [Indexed: 06/16/2023]
Abstract
Measurements were made of the return current instability growth rate, demonstrating its concurrence with nonlocal transport. Thomson scattering was used to measure a maximum growth rate of 5.1×10^{9} Hz, which was 3 times less than classical Spitzer-Härm theory predicts. The measured plasma conditions indicate the heat flux was nonlocal, and Vlasov-Fokker-Planck simulations that account for nonlocality reproduce the measured growth rates. Furthermore, the threshold for the return current instability was measured (δ_{T}=0.017±0.002) to be in good agreement with previous theoretical models.
Collapse
Affiliation(s)
- A L Milder
- Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623, USA
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14623, USA
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - J Zielinski
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - J Katz
- Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623, USA
| | - W Rozmus
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - D Edgell
- Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623, USA
| | - A Hansen
- Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623, USA
| | - M Sherlock
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - C Bruulsema
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - J P Palastro
- Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623, USA
| | - D Turnbull
- Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623, USA
| | - D H Froula
- Laboratory for Laser Energetics, 250 East River Road, Rochester, New York 14623, USA
- Department of Physics and Astronomy, University of Rochester, Rochester, New York 14623, USA
| |
Collapse
|
2
|
Swadling GF, Bruulsema C, Rozmus W, Katz J. Quantitative assessment of fitting errors associated with streak camera noise in Thomson scattering data analysis. Rev Sci Instrum 2022; 93:043503. [PMID: 35489941 DOI: 10.1063/5.0083195] [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: 12/22/2021] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
Thomson scattering measurements in high energy density experiments are often recorded using optical streak cameras. In the low-signal regime, noise introduced by the streak camera can become an important and sometimes the dominant source of measurement uncertainty. In this paper, we present a formal method of accounting for the presence of streak camera noise in our measurements. We present a phenomenological description of the noise generation mechanisms and present a statistical model that may be used to construct the covariance matrix associated with a given measurement. This model is benchmarked against simulations of streak camera images. We demonstrate how this covariance may then be used to weight fitting of the data and provide quantitative assessments of the uncertainty in the fitting parameters determined by the best fit to the data and build confidence in the ability to make statistically significant measurements in the low-signal regime, where spatial correlations in the noise become apparent. These methods will have general applicability to other measurements made using optical streak cameras.
Collapse
Affiliation(s)
- G F Swadling
- Lawrence Livermore National Laboratory, 7000 East Av., Livermore, California 94550, USA
| | - C Bruulsema
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - W Rozmus
- Department of Physics, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
| | - J Katz
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| |
Collapse
|
3
|
Suttle LG, Hare JD, Halliday JWD, Merlini S, Russell DR, Tubman ER, Valenzuela-Villaseca V, Rozmus W, Bruulsema C, Lebedev SV. Collective optical Thomson scattering in pulsed-power driven high energy density physics experiments (invited). Rev Sci Instrum 2021; 92:033542. [PMID: 33819991 DOI: 10.1063/5.0041118] [Citation(s) in RCA: 1] [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: 12/19/2020] [Accepted: 03/06/2021] [Indexed: 06/12/2023]
Abstract
Optical collective Thomson scattering (TS) is used to diagnose magnetized high energy density physics experiments at the Magpie pulsed-power generator at Imperial College London. The system uses an amplified pulse from the second harmonic of a Nd:YAG laser (3 J, 8 ns, 532 nm) to probe a wide diversity of high-temperature plasma objects, with densities in the range of 1017-1019 cm-3 and temperatures between 10 eV and a few keV. The scattered light is collected from 100 μm-scale volumes within the plasmas, which are imaged onto optical fiber arrays. Multiple collection systems observe these volumes from different directions, providing simultaneous probing with different scattering K-vectors (and different associated α-parameters, typically in the range of 0.5-3), allowing independent measurements of separate velocity components of the bulk plasma flow. The fiber arrays are coupled to an imaging spectrometer with a gated intensified charge coupled device. The spectrometer is configured to view the ion-acoustic waves of the collective Thomson scattered spectrum. Fits to the spectra with the theoretical spectral density function S(K, ω) yield measurements of the local plasma temperatures and velocities. Fitting is constrained by independent measurements of the electron density from laser interferometry and the corresponding spectra for different scattering vectors. This TS diagnostic has been successfully implemented on a wide range of experiments, revealing temperature and flow velocity transitions across magnetized shocks, inside rotating plasma jets and imploding wire arrays, as well as providing direct measurements of drift velocities inside a magnetic reconnection current sheet.
Collapse
Affiliation(s)
- L G Suttle
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - J D Hare
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - J W D Halliday
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - S Merlini
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - D R Russell
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | - E R Tubman
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| | | | - W Rozmus
- Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
| | - C Bruulsema
- Theoretical Physics Institute, University of Alberta, Edmonton, Alberta T6G 2J1, Canada
| | - S V Lebedev
- Blackett Laboratory, Imperial College, London SW7 2BW, United Kingdom
| |
Collapse
|
4
|
Swadling GF, Bruulsema C, Fiuza F, Higginson DP, Huntington CM, Park HS, Pollock BB, Rozmus W, Rinderknecht HG, Katz J, Birkel A, Ross JS. Measurement of Kinetic-Scale Current Filamentation Dynamics and Associated Magnetic Fields in Interpenetrating Plasmas. Phys Rev Lett 2020; 124:215001. [PMID: 32530650 DOI: 10.1103/physrevlett.124.215001] [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: 04/16/2019] [Revised: 09/20/2019] [Accepted: 05/05/2020] [Indexed: 06/11/2023]
Abstract
We present the first local, quantitative measurements of ion current filamentation and magnetic field amplification in interpenetrating plasmas, characterizing the dynamics of the ion Weibel instability. The interaction of a pair of laser-generated, counterpropagating, collisionless, supersonic plasma flows is probed using optical Thomson scattering (TS). Analysis of the TS ion-feature revealed anticorrelated modulations in the density of the two ion streams at the spatial scale of the ion skin depth c/ω_{pi}=120 μm, and a correlated modulation in the plasma current. The inferred current profile implies a magnetic field amplitude ∼30±6 T, corresponding to ∼1% of the flow kinetic energy, indicating that magnetic trapping is the dominant saturation mechanism.
Collapse
Affiliation(s)
- G F Swadling
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - C Bruulsema
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2E1
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - F Fiuza
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - D P Higginson
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - C M Huntington
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - H-S Park
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - B B Pollock
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| | - W Rozmus
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2E1
- SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - H G Rinderknecht
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - J Katz
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - A Birkel
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - J S Ross
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
| |
Collapse
|