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Li R, Huang TW, Ju LB, Yu MY, Zhang H, Wu SZ, Zhuo HB, Zhou CT, Ruan SC. Nanoscale Electrostatic Modulation of Mega-Ampere Electron Current in Solid-Density Plasmas. PHYSICAL REVIEW LETTERS 2021; 127:245002. [PMID: 34951809 DOI: 10.1103/physrevlett.127.245002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 06/07/2021] [Accepted: 11/02/2021] [Indexed: 06/14/2023]
Abstract
Transport of high-current relativistic electron beams in dense plasmas is of interest in many areas of research. However, so far the mechanism of such beam-plasma interaction is still not well understood due to the appearance of small time- and space-scale effects. Here we identify a new regime of electron beam transport in solid-density plasma, where kinetic effects that develop on small time and space scales play a dominant role. Our three-dimensional particle-in-cell simulations show that in this regime the electron beam can evolve into layered short microelectron bunches when collisions are relatively weak. The phenomenon is attributed to a secondary instability, on the space- and timescales of the electron skin depth (tens of nanometers) and few femtoseconds of strong electrostatic modulation of the microelectron current filaments formed by Weibel-like instability of the original electron beam. Analytical analysis on the amplitude, scale length, and excitation condition of the self-generated electrostatic fields is clearly validated by the simulations.
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Affiliation(s)
- R Li
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
- College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - T W Huang
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - L B Ju
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - M Y Yu
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - H Zhang
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - S Z Wu
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - H B Zhuo
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - C T Zhou
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
| | - S C Ruan
- Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Advanced Material Diagnostic Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen 518118, People's Republic of China
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Evidence of radial Weibel instability in relativistic intensity laser-plasma interactions inside a sub-micron thick liquid target. Sci Rep 2020; 10:9872. [PMID: 32555513 PMCID: PMC7303142 DOI: 10.1038/s41598-020-66615-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 05/18/2020] [Indexed: 11/15/2022] Open
Abstract
Super-intense laser plasma interaction has shown great promise as a platform for next generation particle accelerators and sources for electron, x-rays, ions and neutrons. In particular, when a relativistic intense laser focus interacts with a thin solid density target, ionized electrons are accelerated to near the speed of light (c) within an optical cycle and are pushed in the forward and transverse directions away from focus, carrying a significant portion of the laser energy. These relativistic electrons are effectively collisionless, and their interactions with the ions and surrounding cold electrons are predominantly mediated by collective electromagnetic effects of the resulting currents and charge separation. Thus, a deeper understanding of subsequent high energy ions generated from various mechanisms and their optimization requires knowledge of the relativistic electron dynamics and the fields they produce. In addition to producing MV/m quasi-static fields, accelerating the ions and confining the majority of the electrons near the bulk of the laser target, these relativistic electron currents are subject to plasma instabilities like the Weibel instability as they propagate through the thermal population in the bulk target. In this work, we present high temporal (100 fs) and spatial (1 μm) resolution shadowgraphy video capturing relativistic radial ionization front expansion and the appearance of filamentation radiating from the laser spot within a sub-micron thick liquid sheet target. Filamentation within the region persists for several picoseconds and seeds the eventual recombination and heating dynamics on the nanosecond timescale. A large scale three-dimensional particle-in-cell (PIC) simulation of the interaction revealed the presence of strong magnetic fields characteristic of Weibel Instability, and corroborated the relativistic radial expansion of the ionization front, whose speed was determined to be 0.77c. Both the experimental and simulation results strongly point towards the target field ionization and the outward expanding hot electron current as the cause of the radial expansion.
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Edwards MR, Shi Y, Mikhailova JM, Fisch NJ. Laser Amplification in Strongly Magnetized Plasma. PHYSICAL REVIEW LETTERS 2019; 123:025001. [PMID: 31386488 DOI: 10.1103/physrevlett.123.025001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 05/28/2019] [Indexed: 06/10/2023]
Abstract
We consider backscattering of laser pulses in strongly magnetized plasma mediated by kinetic magnetohydrodynamic waves. Magnetized low-frequency (MLF) scattering, which can occur when the external magnetic field is neither perpendicular nor parallel to the laser propagation direction, provides an instability growth rate higher than Raman scattering and a frequency downshift comparable to Brillouin scattering. In addition to the high growth rate, which allows smaller plasmas, and the 0.1%-2% frequency downshift, which permits a wide range of pump sources, MLF scattering is an ideal candidate for amplification because the process supports an exceptionally large bandwidth, which particle-in-cell simulations show produces ultrashort durations. Under some conditions, MLF scattering also becomes the dominant spontaneous backscatter instability, with implications for magnetized laser-confinement experiments.
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Affiliation(s)
- Matthew R Edwards
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Yuan Shi
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - Julia M Mikhailova
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Nathaniel J Fisch
- Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544, USA
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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