Generation of Superponderomotive Electrons in Multipicosecond Interactions of Kilojoule Laser Beams with Solid-Density Plasmas
- Univ. of California, San Diego, CA (United States)
- Univ. of Texas, Austin, TX (United States)
- Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL)
- General Atomics, San Diego, CA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
The interaction of a multipicosecond, kilojoule laser pulse with a surface of a solid target has been demonstrated to produce electrons with energies far beyond the free-electron ponderomotive limit $$m_{e}c^{2}a^{2}_{0}$$/2. Particle-in-cell simulations suggest that an increase in the pulse duration from 1 to 10 ps leads to the formation of a low-density shelf (about 10% of the critical density). The shelf extends over 100 μm toward the vacuum side, with a nonstationary potential barrier forming in that area. Electrons reflected from the barrier gain superponderomotive energy from the potential. Some electrons experience an even greater energy gain due to ponderomotive acceleration when their “dephasing rate” $$R = γ – p_{x}/m_{e}c$$ drops well below unity, thus increasing acceleration by a factor of 1/$$R$$. Furthermore, both 1D and 2D simulations indicate that these mechanisms are responsible for the generation of extensive thermal distributions with $$T_{e}$$ > 10 MeV and a high-energy cutoff of hundreds of MeV.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Grant/Contract Number:
- AC52-07NA27344; NA0000870; FG02-05ER54834; FC02-04ER54789; NA0002008; FG02-04ER54742; FG02- 04ER54742
- OSTI ID:
- 1579609
- Alternate ID(s):
- OSTI ID: 1247076
- Report Number(s):
- LLNL-JRNL-799339; PRLTAO; 833827; TRN: US2102233
- Journal Information:
- Physical Review Letters, Vol. 116, Issue 15; ISSN 0031-9007
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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