Investigation of 110 keV/u heavy ion beams interaction with hydrogen plasma

The goal of this work is the experimental measurement and numerical simulation of the low energy ion beam interaction with hydrogen plasma. The detailed knowledge on the interaction between fast heavy ions and hot plasmas is not only a key issue in ion-driven inertial confinement fusion programs, but also an interesting subject related to atomic physics. Although, there are several theories on the energy loss of heavy ions in plasmas (1- 3), there are still not enough experimental data to confirm these theoretical formulas. The stopping of projectile ions in hydrogen plasma targets has been recently measured experimentally mainly in projectile energy range about 1 MeV/u. However, few investigations of the stopping power of non-hydrogenic plasma target were conducted so far. Furthermore, the data base is not yet systematically compiled, especially for projectile energies below 0.5 MeV/u. With these points, new experimental data will give additional information for understanding interaction processes of low energy heavy ions in plasma. Background and justification For lower kinetic energies, the stopping power of plasma is expected to be even higher than for the previous beam energies (2,4) whereas the stopping power of cold matter decreases by 1 order of magnitude. This qualitatively different behaviour for the stopping power of hot and cold matter at low beam energies originates from the higher charge state of the beam ions (Zeff) in highly ionized plasma. The dynamic equilibrium of ionization and recombination determines the charge state of the projectile ions. The recombination process is reduced compared to the capture of a bound electron because the direct capture of a free electron into a moving projectile violates the simultaneous fulfilment of energy and momentum conservation (2,5). Therefore, the charge state of the projectiles passing plasma is expected to be higher than for ions in a cold, neutral gas. This effect is most important at low particle velocities (< 500 keV/u), where the recombination rate in cold gas increases drastically. In this energy range only two series of experiments were done. In (6,7) the