Characterization of heavy-ice deposition-thickness on flat metal targets for deuteron ion acceleration

Summary form only given. Heavy ice constitutes a source of deuteron ions that are accelerated by the target-normal-sheath-acceleration mechanism to energies in excess of 1 MeV¹. The thickness of cryogenically-cooled, heavy-ice deposits on the rear surface of laser-irradiated flat metal foils is inferred by a method of ratios. The relationship between the ice thickness and the injected heavy water volume has been established. This relationship is used to determine the injection volumes that are required for sub-micron layering. Known volumes of heavy water at vapor pressure (~17.5 torr at 20 degrees) are injected into the vacuum chamber, nominally held at 10^-5 torr, and onto the foil through a 3mm diameter nozzle. Liquid nitrogen lines, non-rigidly coupled to the foil, cool the foil down to around -150 °C. The heavy ice deposition is observed in real time using a Mitutoyo 10× infinity corrected microscope objective that provides around 2 um of spatial resolution. Experiments to characterize the spectrum and brightness of ions accelerated from the heavy ice will be carried out using the GHOST laser facility at the University of Texas at Austin.