With Intense Ion and Laser Beams

Laser driven particle acceleration and measurements ofion energy loss in plasma largely rely on suitable targets toachieve good particle beam and plasma quality. Recent re-search results [2] indicate that cryogenic targets allow forvery high ion energies. Advantages of our cryogenic tar-gets include high purity at solid density in a self-supportedstructure as well as fitness for medium repetition rates.Within the High Power Laser Energy Research (HiPER)collaboration, our group works on thin cryogenic targetsfrom deuterium and hydrogen to be used in laser driven ionacceleration and energy loss in plasma experiments. Experimental Results Our setup for making cryogenic targets consists of a vac-uum chamber with a cooling head attached, a custom-builtgrowing chamber, and various diagnostics. With this setupwe are able to make cryogenic targets from a large varietyof gases, including argon, deuterium, hydrogen, and neon.We made solid cryogenic targets with an initial thicknessof some hundred micrometers from gaseous deuterium.The thickness of the target was measured using electronscattering. After growing the target in a custom-built grow-ing chamber the chamber was removed and the target’sthickness was reduced by sublimation (see Figure 2).Cryogenic deuterium targets were used in preliminary ex-periments to measure energy loss of a heavy-ion beam ina deuterium plasma by irradiating the targets from twosides with both the PHELIX laser and the nhelix laser (see Work supported by High Power Laser Energy Research (HiPER) andBundesministerium für Bildung und Forschung (BMBF).Figure 2: Deuterium target thickness vs. time. [1] Figure 1) at the GSI Helmholtzzentrum für Schwerionen-forschung GmbH, Darmstadt, Germany.