Observation of the charge neutrality of the ions from target short-pulse laser interaction experiments

Intended to simulate the early stage of the plasma (preformed plasma) formation in the higher (1020 W cm-2) intensity experiments (in which the plasma density profile rules laser absorption thus conversion efficiency from laser into hot electrons, ions and x-rays) experiments using solid target were done under a peak intensity (main laser pulse) of up to ∼1015 W cm-2 and pre-pulse and pedestal intensity of ∼103 times lower than main pulse. With pedestal, significant enhancement of laser absorption was observed with pedestal condition. Charge neutralization of the ions from the plasma was measured by biased charge collectors. Earlier part of the ion were almost un-neutralized in with or without pedestal condition, and the later part of the ions (≤ few keV) were partially neutralized (≥40%). These not-perfect charge neutralization results is different from the longer nano-seconds pulse experimental results. (author)