INTERIOR PLASMA DIAGNOSTICS OF ARCJET THRUSTERS

We review past experimental measurements of internal now properties of arcjet thrusters. These measurements are generally classified as eith er intrusive, requiring design changes to prototype thrusters, or noni ntrusive, and include measurements of cathode temperature, as well as static pressure, flow temperatures (vibrational, rotational, electroni c, translational), electron density, and velocity throughout the inter ior region extending to the exit plane. Comparisons are made to availa ble model predictions. These measurements, performed on a wide range o f thrusters, and operating on variety of propellants, indicate that th e nozzle plasma flow may be removed from local thermodynamic equilibri um.