ИСТИНА

The experimental results on the relativistic laser-plasma interactions of femtosecond laser pulse with nanoscale structured and flat targets with contrast control are presented. In our experiments we used an ultrafast pulse from the Ti:Sa laser system (pulse duration - 50 fs, energy on target - up to 30 mJ, wavelength - 800 nm, repetition rate - 10 Hz, peak intensity - up to 5×1018 W/cm2). The experiments were conducted with contrast control by special controlled prepulse with different delay relative to the main pulse. The controlled prepulse was created by Nd:YAG laser with active Q-switching, a wavelength of 532 nm. (second harmonic - 1064 nm.), pulse duration - 6 ns., pulse energy - up to 250 mJ at the main harmonic. Also, experiments were conducted with ultrahigh (with XPW contrast level < 10−10) contrast level. Ions were registered with the use time-of-flight magnet spectrometer with the charge-to-mass (Z/M) separation and Thomson parabola mass spectrometer. In experiments with low contrast level there are no high energy ions. Also, it was demonstrated that with high contrast level there is no significant difference between flat bulk and nanoscale structured target. In experiments with ultrahigh contrast high-Z ions (up to Si12+ and even fully stripped Si14+, which not registered in experiments with high contrast level) were registered. Also it was demonstrated significant increase in ion energy and ion flux depending on nanostructured target compared to experiment with flat target. Experiments with nanostructured targets was supported by Russian Science Foundation grant No 18-79-10160. Ion diagnostic development and experiments with contrast control by the artificial prepulse were supported by Russian Fund for Basic Research under grants No 18-32-00416 and 19-02-00104