Current distribution and resistance characteristics in plasma injectors for electrothermal-chemical launch

A two-dimensional model is developed for investigating electrical conductio n in plasma injectors that consist of a periodic array of solid and plasma conductors. The model studied is general but the basic analysis applies to a variety of devices and experimental situations. Calculation are undertake n to determine the preferred conduction pathways as well as the impedance i n such an injector as a function of several relevant parameters. These para meters include the relative dimensions of the solid and the aspect ratio of the conduction domain. It is shown that under some conditions the current will flow predominantly in the plasma and bypass the low-resistance path pr ovided by the solid. Such an event is undesirable far several reasons discu ssed, and methods for preventing its occurrence are suggested. Additional c alculations include the resistance of the injector and the fractional amoun t of current that flows through the solid. These quantities are shown to de pend on the various length scales pertinent to the problem.