Variable frequency matching to a radiofrequency source immersed in vacuum

A low-weight (0.12 kg) low-volume fixed ceramic capacitor impedance matching system is developed for frequency agile tuning of a radiofrequency (rf) Helicon plasma thruster. Three fixed groups of capacitors are directly mounted onto a two loop rf antenna with the thruster immersed in a vacuum chambe...

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Bibliographic Details
Published in:Journal of physics. D, Applied physics Applied physics, 2013-09, Vol.46 (36), p.365203-1-6
Main Authors: Charles, C, Boswell, R W, Bish, A
Format: Article
Language:English
Subjects:
Antennas
Capacitors
Ceramics
Exact sciences and technology
Ignition
Physics
Physics of gases, plasmas and electric discharges
Physics of plasmas and electric discharges
Plasma (physics)
Plasma devices
Radiofrequency
Thrusters
Tuning
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Summary:A low-weight (0.12 kg) low-volume fixed ceramic capacitor impedance matching system is developed for frequency agile tuning of a radiofrequency (rf) Helicon plasma thruster. Three fixed groups of capacitors are directly mounted onto a two loop rf antenna with the thruster immersed in a vacuum chamber. Optimum plasma tuning at the resonance frequency is demonstrated via measurements of the load impedance, power transfer efficiency and plasma density versus driving frequency in the 12.882-14.238 MHz range. The resonance frequency with the plasma on is higher than the resonance frequency in vacuum. The minimum rf power necessary for ignition decreases when the ignition frequency is shifted downwards from the resonance frequency. This development has direct applications in space qualification and space use of rf plasma thrusters.
ISSN:0022-3727
1361-6463
DOI:10.1088/0022-3727/46/36/365203