Abrupt Change in X-ray and Ion Emission of the PALS Laser Plasma at Laser Intensity of ∼1015 W/cm2

In the paper we summarise and compare the original data concerning x-ray and ion emission obtained in some laser experiments on the PALS laser system, Prague, which were carried out using different targets and laser energy. Typical patterns of changing the x-ray and the ion emission in dependence on the state of laser beam focusing are presented and discussed. Radical changes in x-ray, ion emission and crater formation are observed in the vicinity of best focus when laser intensity exceeds the level of about x1014 Wcm-2. Some practical conclusions concerning the use of x-ray and ion diagnostics in the experiments at high laser energy and the condition of high laser beam focusing are drawn out