Direct electron acceleration in multi-kilojoule, multi-picosecond laser pulses
The physics mechanism behind the acceleration of electrons to energies much higher than the laser ponderomotive potential is reported. While electrons with these energies have been observed for the last twenty years at the one percent level, it is only with the recent advent of high power lasers with extended pulse durations, large focal spots, and high intensities that significant numbers (>10%) of the so-called “superponderomotive” electrons have been observed. Evidence is provided that the dominant acceleration mechanism of superponderomotive electrons is direct acceleration by the electromagnetic (EM) wave of the laser as they co-propagate in an under-dense plasma; one-dimensional particle-in-cell simulations yield electron spectra with typically ten times the ponderomotive temperature. Direct acceleration requires tens of plasma wavelengths of under-dense plasma, as well as pulse durations of tens of plasma periods, conditions that can be found in large focal spot multi-picosecond laser pulses. It is shown that the plasma simply provides the source of accelerated electrons and a variety of methods to inject a significant population of electrons into the EM waves at relativistic energy.
- Research Organization:
- Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC52-07NA27344; 19-SI-002; 17-ERD-039
- OSTI ID:
- 1788313
- Alternate ID(s):
- OSTI ID: 1682367
- Report Number(s):
- LLNL-JRNL-805885; 1009924; TRN: US2210581
- Journal Information:
- Physics of Plasmas, Vol. 27, Issue 10; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
First demonstration of ARC-accelerated proton beams at the National Ignition Facility
Plasma mirror focal spot quality for glass and aluminum mirrors for laser pulses up to 20 ps