Fast ion generation in the cathode plasma jet of a multipicosecond laser-triggered vacuum discharge

Abstract

Ion generation in the cathode plasma jet of a moderate-current (approximately 2.3 kA), low-energy (< or = 20 J) vacuum spark discharge triggered by approximately 27 ps, 10 mJ laser pulses is studied using time of flight technique. Fastest ion velocity and velocity corresponding to the peak of the time of flight signals for Al cathode were measured to be approximately 5.25x10(8) cm/s (energy of approximately 143 keV/u) and approximately 8.1x10(7) cm/s (energy of approximately 3.4 keV/u), respectively. Corresponding velocities in the case of ions generated from laser-produced Al plasma (energy of approximately 550 mJ, intensity of approximately 10(14) W/cm(2)) were found to be much smaller, viz., approximately 1.05x10(8) cm/s (energy of approximately 5.75 keV/u) and approximately 2.63x10(7) cm/s (energy of approximately 0.36 keV/u), respectively. Study shows efficient acceleration of ions in a current-carrying cathode plasma jet of a small-energy multipicosecond laser-triggered spark discharge as compared with that in a high-energy multipicosecond laser-produced plasma plume.