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

Ion generation in the cathode plasma jet of a moderate-current (similar to 2.3 kA), low-energy (< 20 J) vacuum spark discharge triggered by similar to 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 similar to 5.25x10(8) cm/s (energy of similar to 143 keV/u) and similar to 8.1x10(7) cm/s (energy of similar to 3.4 keV/u), respectively. Corresponding velocities in the case of ions generated from laser-produced Al plasma (energy of similar to 550 mJ, intensity of similar to 10(14) W/cm(2)) were found to be much smaller, viz., similar to 1.05x10(8) cm/s (energy of similar to 5.75 keV/u) and similar to 2.63x10(7) cm/s (energy of similar to 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.