Field Direction Dependent Particle Heating and Plasma Production in a Helicon Source

Experiments in helicon sources have shown that more efficient wave-plasma coupling (and therefore higher temperatures and densities) occurs when the antenna excites the m = +1 (i.e., right-hand polarized) helicon wave. Here we present ion and electron temperature measurements, and electron density m...

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Bibliographic Details
Main Authors: Stevenson, K. J., Gilbert, T., Srivastava, P., Paul, M., Shi, P., Yadav, S., Nirwan, R.S., Steinberger, T., Scime, E.
Format: Conference Proceeding
Language:English
Subjects:
Antenna measurements
Heating systems
Helical antennas
Ions
Magnetic field measurement
Phase measurement
Temperature measurement
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Summary:Experiments in helicon sources have shown that more efficient wave-plasma coupling (and therefore higher temperatures and densities) occurs when the antenna excites the m = +1 (i.e., right-hand polarized) helicon wave. Here we present ion and electron temperature measurements, and electron density measurements, on both sides of a helical antenna in a helicon source as a function of antenna frequency and magnetic field strength. These measurements were obtained for two different background magnetic field directions. For both field directions, significant ion heating at frequencies near the lower hybrid frequency was observed. A remarkable and unexpected density difference (~ 2 orders of magnitude) was observed in the downstream region when the magnetic field direction was reversed. Radial wave field profiles and phase measurements were measured to identify the polarization of the helicon waves for both background magnetic field directions, on both sides of the antenna. It was confirmed that the region of hotter ion temperature and higher plasma density were on the m = +1 side of the antenna.
ISSN:2576-7208
DOI:10.1109/ICOPS45740.2023.10481064