Influence of source parameters on the properties of a plasma jet



Journal Title

Journal ISSN

Volume Title



In the Plasma Edge Cathode scheme, a nearly stationary plasma cathode is formed by partially obstructing a well directed plasma with a material edge. Electrons are extracted in a direction normal to the flow of plasma. An electron current density of 100 A/cm2 is theoretically possible. In order to achieve this desired current density, certain temperature, density, and ionization levels are required in the plasma. The motivation for the work discussed in this thesis, is to determine how changes in the source parameters affect these plasma characteristics. The plasma source consists of an RC storage circuit charged to 20 kV and a triggered switch. When the switch is triggered, a surface flashover occurs over a coaxially arranged dielectric to produce the plasma. The source dielectric material and geometry, charging voltage polarity, and the charge circuit inductance are the parameters which will be varied. The emphasis in this work has been on the development of a triple Langmuir probe and the corresponding circuitry to diagnose the temperature of the plasma. Faraday cup probes and a time of flight mass spectrometer are also used as diagnostics to find the plasma composition and velocity of the various species. The data acquisition is automated by the use of an HP Vectra computer and three HP digital oscilloscopes. The program sets up the oscilloscopes to perform the measurements and then transfers the data to the computer for analysis. The resulting data are compared in order to better understand the optimum source arrangement for the Plasma Edge Cathode system.



Plasma jets, Plasma diagnostics, Surface discharges (Electricity)