Characterization of multi-jet gas puff targets for high-order harmonic generation using EUV shadowgraphy

Characterization measurements of multi-jet gas puff targets, developed for investigations on high-order harmonic generation (HHG) by a focused laser beam in a gas medium of modulated density, are presented. The targets produced by pulsed injection of gas through a nozzle in a form of a chain of small orifices have been characterized by EUV backlighting at 13.5 nm wavelength. Measurements were performed for nozzles with 5, 7 and 9 orifices of 0.5 mm in diameter each. Density profiles for argon targets have been obtained for the first time.