Large Spectral Shift of Reflected Radiation From Laser Plasmas Generated by High Contrast KrF Laser Pulses

Abstract

Increasing absorption up to more than 90% with increasing intensity was observed in boron and gold laser plasmas heated by KrF laser pulses of high, but still non-relativistic, intensity. The pulses of 700 fs duration had a temporal contrast of 12 orders of magnitude; thus, the laser pulse of more than 10 18 Wcm −2 intensity hit the steep surface of the boron and gold targets. Blue shift of the reflected radiation refers to extreme high acceleration resulting in velocities above 5 × 10 5 ms −1. Brunel absorption and ponderomotive effects are shown to play an important role in the observed phenomena.

Ponderomotive shifts induced by intense laser-driven coherent extreme ultraviolet radiation

“…The present results support the perspective of the extension of such studies in fewphoton processes including inner-shell processes, subject to availability of short and intense enough deep XUV and/or soft x-ray attosecond pulses. Finally, it is worth mentioning that in a more general context, ponderomotion in laser plasmas at longer wavelengths may lead to interesting nuclear effects that have been studied both theoretically [54,55] as well as experimentally [56][57][58]. Whether such effects are observable in more extreme wavelength regions may become a future research topic in the laser plasma community.…”