Date of Graduation
Eberly College of Arts and Sciences
Physics and Astronomy
Earl E. Scime.
Measurements of electron density and perpendicular ion temperatures in an argon helicon plasma are presented for five different antennas: A Nagoya type III antenna, a double-saddle antenna, a 19 cm long m = +1 helical antenna, a 30 cm long m = +1 helical antenna and a 19 cm m = +1 helical antenna with wide straps. Electromagnetic wave measurements in the range from 100 kHz to 50 MHz are also presented for a wide range of plasma parameters. The data show a clear transition between RF power coupling to the plasma to create density and coupling to heat ions. The transition from plasma production to ion heating indicates that the mechanism responsible for heating the ions is distinct from the mechanism responsible for ionizing the plasma in a helicon source. The primary objective of the experiments described here is to identify the operational conditions for a helicon source such that the intrinsic ion heating is minimized without sacrificing density production. Secondary objectives of this project include: identifying the optimal antenna configuration for density production and/or ion heating, investigating the mechanism responsible for ion heating through measurements of the fluctuating magnetic field at the edge of the source, and determining if downstream density measurements can be used as a quantitative measure of the electron density in the helicon source.
Balkey, Matthew M., "Optimization of a helicon plasma source for maximum density with minimal ion heating" (2000). Graduate Theses, Dissertations, and Problem Reports. 1195.