Generation of intense Ni-like X-ray lasers at LULI : from 130 ps to 350 fs pumping pulses

摘要

We compare the results obtained in terms of lasing emission at 13.9nm in Ni-like silver pumped with different pumping pulse durations. We show that short pulses of the order of 100 ps are necessary to generate significant gain in these ions This induces a transient ionisation dynamics which allows to produce Ni-like ions at high temperature. On the other hand we have extended the transient collisional pumping in Ni-like silver towards ultra-short sub-ps heating pulse, using a new method to generate a travelling wave irradiation. We show that the presence of the travelling wave is essential to extract the X-ray laser photons from the transient gain region. The low pump energy of 2×5 Joules used at the target illustrates the high efficiency of this pumping scheme.