Excitation and damping of a self-modulated laser wakefield

Abstract

, "Excitation and damping of a self-modulated laser wakefield" (2000). Spatially, temporally, and angularly resolved collinear collective Thomson scattering was used to diagnose the excitation and damping of a relativistic-phase-velocity self-modulated laser wakefield. The excitation of the electron plasma wave was observed to be driven by Raman-type instabilities. The damping is believed to originate from both electron beam loading and modulational instability. The collective Thomson scattering of a probe pulse from the ion acoustic waves, resulting from modulational instability, allows us to measure the temporal evolution of the plasma temperature. The latter was found to be consistent with the damping of the electron plasma wave.

Pulse radiolysis of liquid water using picosecond electron pulses produced by a table-top terawatt laser system

“…Under these conditions, a collimated beam of 2 MeV electrons is emitted in the laser propagation direction. [4][5][6] The spectrum of the electrons is shown in Fig. 2.…”

“…The duration of each microbunch is less than 18 fs. 5 Because of the large dispersion in the electron energy, the temporal profile is expected to increase as the pulse propagates. The combination of dispersion effects and low repetition rate make quantitative characterization of the electron pulse temporal profile difficult.…”

“…The temporal profile of the macrobunch is believed to be approximately equal to that of the plasma wave which has been measured to be ϳ1.9 ps. 5 The separation between microbunches is equal to the plasma wave period which is 18 fs for a plasma density of 3.4 ϫ10…”

“…It has been shown that by focusing terawatt (10 12 W) laser pulses to intensities у10 18 W/cm 2 in helium gas jets, it is possible to generate electron pulses with a charge of a few nC. [4][5][6] While physicists are interested in this technology to study such phenomena as the generation of superrelativistic electrons and nonlinear quantum electrodynamics, chemists could use these techniques to conduct subpicosecond pulse radiolysis experiments.…”

“…However, one can partially shorten this developmental time frame by exploring the capabilities of laser-based table-top electron generation. [4][5][6] This is a logical stepping stone towards exploration of the same processes that motivate the development of ultrafast pulse radiolysis accelerators.…”