A stochastic model for calculating collisional ionization rates in dense plasmas
Murillo, Michael Sean
Weisheit, Jon C.
Master of Science
A formalism has been developed here in which the collisional ionization rate is determined directly, as a probability of transition due to changes in the plasma's local electric field. The calculations described here are performed within a model which treats hydrogenic ions only, but the generalization to more complex ions is straightforward. The initial state is a hydrogenic state with a reduced ionization potential, and the final state is that of a free particle. This model is effective in treating many scenerios that occur in laser fusion and sub-picosecond laser-matter experiments where high-density conditions exist. The results show that plasma screening of the interaction between target and free electrons serves to reduce the ionization rate while the drop in ionization potential serves to increase the ionization rate. The lowering of the continuum dominates in all calculations performed here and indicates that the enhancement in ionization rate can be as much as an order of magnitude in physically interesting regimes. (Abstract shortened by UMI.)
Plasma physics; Atomic physics