Thin foil acceleration by intense pulsed ion beam ablation

Summary form only given, as follows. Acceleration of thin foil by ablation plasma that is produced by irradiation of an intense pulsed ion beam has been investigated. Ion beam is produced by the Intense Pulsed Ion Beam Facility, ETIGO-II installed at the EDRI of Nagaoka University of Technology. Two different types of diode have been used: 1) magnetically insulated diode (MID) whose hewn energy density is about 50-150J/cm/sup 2/ and 2) spherically-focused plasma focus diode whose beam energy density is up to 4.3kJ/cm/sup 2/. Two kinds of thin foil have been accelerated: 1) aluminum mono-layer with the thickness of 50mm and 100mm and 2) aluminum/gold two-layers foil with various gold layer thickness. In the experiments, observations of accelerated foil are successfully achieved by means of back-lighting high-speed photography. Averaged velocity is measured by time-of-flight method with an electric probe. For the present numerical simulations, we treat the foil as a fluid and interaction of ion beam with target foil is taken into account as its stopping power including any phase of foil material. Lagrange scheme is adapted to this analysis. Calculated foil velocity agrees well with the experimental results for over wide range of incident ion beam energy density 100-4300J/cm2. Maximum velocity is 5km/s. Expected pressure and temperature of ablation plasma are over 10GPa and 30eV. With this range of pressure and temperature, improvement and/or modification of surface characteristics of foil material can be expected. We try to accelerate two-layers type thin foil, which consists of relatively heavier gold or lead to be ablated and lighter aluminum to be: accelerated part. Obtained accelerated velocity reaches its maximum at the certain thickness of gold layer. Although predicted the thickness providing the maximum velocity is slightly different from experimental result because of uncertainty of gold layer thickness in experiments, general characteristics can be well explained by the numerical simulation.