Impulsive electric fields driven by high-intensity laser matter interactions

Abstract

The interaction of high-intensity laser pulses with matter releases instantaneously ultra-large currents of highly energetic electrons, leading to the generation of highly-transient, large-amplitude electric and magnetic fields. We report results of recent experiments in which such charge dynamics have been studied by using proton probing techniques able to provide maps of the electrostatic fields with high spatial and temporal resolution. The dynamics of ponderomotive channeling in underdense plasmas have been studied in this way, as also the processes of Debye sheath formation and MeV ion front expansion at the rear of laser-irradiated thin metallic foils. Laser-driven impulsive fields at the surface of solid targets can be applied for energy-selective ion beam focusing.

Plasma channeling by multiple short-pulse lasers

“…The channeling or boring of an intense laser pulse in plasma and ion acceleration have been investigated extensively (Wilks et al, 1992;Borisov et al, 1992;Tabak et al, 1994;Zepf et al, 1996;Borghesi et al, 1997Borghesi et al, , 2002Borghesi et al, , 2007Fuchs et al, 1998;Vshivkov et al, 1998;Tanaka et al, 2000;Willi et al, 2001;Kodama et al, 2001;Najmudin et al, 2003;Hoffmann et al 2005;Flippo et al 2007;Laska et al 2007;Lei et al, 2007). In the relativistic-intensity regime, the relativistic ponderomotive force, which is proportional to the gradient of the laser intensity, dominates the laserplasma interaction (f p / ÀrI).…”

Investigations of Field Dynamics in Laser Plasmas with Proton Imaging

“…The temporal characteristics of the proton emission have been discussed theoretically and are supported by experimentally gained arguments in several publications [1,3,93,101,102]. The acceleration of the protons takes place on a picosecond timescale.…”

“…Therefore proton imaging can be applied for different objectives. It can be used to visualize density gradients, for example in shocked material [110,111] or to detect electric and magnetic fields generated by laser matter interaction (proton deflectometry) [102,112]. With proton imaging the ion acceleration process itself [105,113] was investigated recently.…”

“…The proton beam usually has a broad and continuous energy distribution -but the energetic protons are all accelerated within 1-2 ps [1,3,93,101,102]. Starting at nearly the same time from the target, they reach the interaction target at different times.…”

“…The laser pulse ionizes the gas around the droplet and the droplets surface by the wings of the pulse. While propagating through the plasma the laser breaks into filaments and creates magnetic fields which deflect the proton beam [102]. The surrounding gas is caused by the evaporation of the water into vacuum and the evaporation of the droplets due to the incident laser light.…”