Investigations of ion streams emitted from plasma produced with a high-power picosecond laser

Abstract

This work reports on investigations of parameters of ion streams emitted from a plasma produced with a picosecond laser at the power densities ≥1016 W/cm2. Not many papers dealing with such investigations have been published up to now, in spite of the fact that the application of precise corpuscular diagnostics enables better learning of the physical properties of such a plasma. As a result of the investigations carried out, the average and maximum energies of Cu ions were 30 keV and 150 keV, respectively. The maximum charge of Cu ions was 13+. The dependencies of parameters of ions emitted from the plasma on the laser-pulse energy as well as on the location of the focus of the laser beam with respect to the target's surface were also found out. The results obtained from the ion measurements in relation to the results of measurements of X ray are discussed.

Computations for nonlinear force driven plasma blocks by picosecond laser pulses for fusion

“…From our experience of relativistic self-focusing (Hora 1975;Jones et al 1982;Häuser et al 1992;Osman et al 1999;, it is necessary to have plasmas of about critical density with a depth of 1 to 2 times the laser beam diameter in vacuum for relativistic self-focusing in front of the irradiated target. We could conclude that the ps laser pulse in the experiment (Badziak et al 1999) could not have produced this necessary plasma for the relativistic shrinking of the beam. At best it can only produce plasma of less depth than one third of the beam diameter in front of the target.…”

“…The final result for the maximum ion energy ε trans after relativistic self-focusing (Hora 1975;Jones et al 1982;Häuser et al 1992;Osman et al 1999;, fitting with all the long years of observations (Haseroth et al 1996) with laser pulses longer than 100 ps, was found to be dependent on the laser power P , the ion charge Z and the focused beam Number of (integrated signal) emitted fast ions and thermal ions from a perpendicular irradiated copper target at neodymium glass irradiation for 1.2 ps pulses depending on the laser pulse energy focused to a 30 wavelength diameter beam at the target surface with suppression of a prepulse by 10 8 for a time less then 100 ps before the main pulse arrived. During the last 100 ps the contrast ratio was about 10 4 (Badziak et al 1999(Badziak et al , 2003Hora, Badziak et al 2002a). diameter δ in multiples of the laser vacuum wave length (larger than 0.6) as in the following relation:…”

“…One of them was seen through the emission of ions (Badziak et al 1999). Irradiating copper with 1.5 ps neodymium glass laser pulses, up to 0.21 TW power focused to about 30 µm diameter, resulted in maximum Cu +13 ion energies of up to 450 keV.…”

“…The measurements of Badziak et al (1999) used ps pulses with very clean contrast ratio for the elimination of prepulses for comparison with interaction of nanosecond (ns) laser pulses (Wolowski et al 2002;Badziak et al 2003). The aim was to study of several energetic ion groups above thermally generated ions.…”

Laser-driven generation of fast particles

“…The S-LPA mechanism was actually discovered at the end of the nineties [38], but just recently this mechanism has been relatively well understood and proved by both numerical simulations and experiments [19,20,[39][40][41][42].…”