Interaction experiments using thin-foil-discharge warm-dense plasma

We developed a thin-foil-discharge (TFD) plasma target for beam–plasma interaction experiments. A discharge current of several tens of kilo-amperes rapidly heated and ionized a thin aluminum foil of sub- to several micrometers thick. The target areal density seen by projectiles was expected to be almost constant during several hundred nanoseconds from the ignition of the discharge because the size of the thin foil was chosen to be much larger than the cross-section of the incident beam. The optical observation of the plasma using a fast framing camera showed that the TFD plasma expanded one-dimensionally in the early stage of the discharge. We determined the plasma density and temperature from the observed plasma thickness and the deposited electrical power with equation-of-state data. A one-dimensional plasma expansion model was developed and used to examine the expected plasma parameters under various initial conditions. We also performed beam–plasma interaction experiments with fully stripped ions of 4.3MeV/u. The energy loss of silicon ions was measured as a function of time by the TOF method.