Encounter interactions of counter-streaming laser-produced plasmas in magnetic field

Experiments were carried out on the encounter interactions of two laser-produced, counter-streaming plasmas along a magnetic field. This study was motivated by the problem of filling toroidal (typically stellarator) or large-scale open-ended magnetic containers with laser-produced plasma, where simultaneous plasma production at multipositions in a container is often required. The experimental results indicate that (1) the translational kinetic energy of ions is converted to the plasma thermal energy by encounter interactions and the electron temperature increases by a factor of 3 to 6, and (2) the particle-loss across the magnetic field is not enhanced. Theoretical considerations indicate that the thermalization may be attributed to Coulomb interactions, rather than shock-formation or microinstability excitations. This thermalization is useful for recovering the thermal energy from the adiabatic cooling of a flowing laser-produced plasma in its expansion phase. (author)