Enhanced x-ray emission from hot plasma produced by double-pulse laser irradiation of solid target at atmospheric conditions

Abstract

We present the results of our experiments directed to the suppression of atmospheric gases influence on delivering of superintense femtosecond laser radiation to solid target at atmospheric conditions.The suppression of atmospheric gases effects is attained by expositing the target to a double-pulse radiation and caused by reducing gas density near the target surface). In our scheme the first pulse (nanosecond UV pulse from XeCl excimer laser) acts as a vacuum pump. The second laser pulse (tightly focused femtosecond pulse) delaying up to several microseconds respect to the first laser pulse delivers the basic energy necessary for switching a hot plasma on the target surface. We have observed the maximum Xray yield increasing up to 17 times under double pulses exposure compare with the single femtosecond pulse regime.