Basic Measurements in a Rail Type Plasma Gun

The rail-type plasma-gun is a well suited laboratory set-up for the experimental determination of the physical properties of short lived plasmas. The ONERA plasma-gun is the most conventional rail type gun, with two cylindrical electrodes; an electrical discharge between two auxiliary electrodes generates the plasma whenever a puff of argon is injected into the plasma gun. Measurements on the set-up are devised to give the following data: - mass flow rate through the injection nozzle or amount of argon corresponding to each puff; - current and voltage during a discharge; - self induction of the rails; - shape and displacement of the plasma column (magnetic coil probe and photo-cell recordings). Though not necessarily an efficient space propulsion device, the parallel rail plasma-gun allows the development and improvement of many experimental techniques, which can be used for the study of more efficient electric thrustors.