Cryogenic Pellet Laser Plasma Source Targets

Abstract

We have developed a new laser plasma cryogenic target scheme that achieves high conversion efficiency (CE), but produces no condensable target debris and low vaporized target gas loads. This scheme employs a solidified pellet of a rare gas, such as Xe, which is irradiated in free flight by a focused drive laser. The pellet is made small enough that gas loads produced following target vaporization are manageable, but large enough to fully intercept the laser energy at its focus. To assess the fundamental utility of cryogenic pellet targets, we have examined the conversion efficiency, extreme ultraviolet (EUV) spectroscopy, and fragmentation dynamics of Xe pellets irradiated with a 248 nm KrF laser.