Date of Award

Fall 2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical and Computer Engineering

Committee Director

Chunqi Jiang

Committee Member

Tom Powers

Committee Member

Linda Vahala

Abstract

The state-of-the-art cryomodules for particle accelerators use superconducting radio-frequency (SRF) cavities. It is known that accumulation of hydrocarbon impurities reduces the cavity surface work function, decreasing cryomodule performance metrics such as field emission, thermal stability, and accelerating gradients. An in-situ method of plasma processing has recently been developed to clean the cavities and restore cryomodule performance [1]. This study is to understand the properties of the low-pressure plasmas generated in a C100 SRF cavity and ultimately to improve the performance of plasma surface cleaning using optical emission spectroscopy. Using a 500 mm focal length Czerny-Turner monochromator coupled with a photomultiplier tube, emission spectra including the Balmer series hydrogen emission line Hα of Ar or Ar + 2% H2 plasma at a range of 50–150 mTorr were recorded. The effects of gas composition, gas pressure, mode frequency, and input power on the optical emission from the plasma were investigated.

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In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

DOI

10.25777/yyha-ec81

ISBN

9798302862396

ORCID

0000-0001-5572-5998

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