Document Type
Article
Publication Date
2019
DOI
10.1063/1.5115043
Publication Title
Journal of Applied Physics
Volume
126
Issue
10
Pages
103302 (1-15)
Abstract
A comparative analysis of two popular spectroscopy techniques is conducted in a coaxial cylindrical capacitively coupled discharge designed for the plasma processing of superconducting radio frequency (SRF) cavities. The density of the metastable and resonant levels in Ar is measured in both Ar and Ar/Cl2 discharges to properly characterize the unique discharge system and aid in the development of a cavity etching routine. The first method, deemed the “branching fraction method,” utilizes the sensitivity of photon reabsorption of radiative decay to measure the lower state (metastable and resonant) densities by taking ratios of spectral lines with a common upper level. This method has been gaining popularity as it does not require any a priori knowledge about the electron energy distribution. The second method is a tunable diode laser absorption spectroscopy technique that measures the thermal Doppler broadening of spectral lines, from which the neutral gas temperature and lower state density of the transition can be evaluated. The two methods were conducted in tandem, while external parameters that were empirically determined to be important to the etching mechanism of SRF cavities are varied. Relationships between the excited state densities and the external parameters are presented for both spectroscopy methods and conclusions about the effects of these parameters on the discharge are stated when appropriate.
Original Publication Citation
Peshl, J., McNeill, R., Sukenik, C. I., Nikolić, M., Popović, S., & Vŭsković, L. (2019). Argon metastable and resonant level densities in Ar and Ar/Cl2 discharges used for the processing of bulk niobium. Journal of Applied Physics, 126(10), 103302. doi:10.1063/1.5115043
ORCID
0000-0001-5025-2546 (Sukenik), 0000-0002-3668-4841 (Popović)
Repository Citation
Peshl, Jeremy; McNeill, Roderick; Sukenik, Charles I.; Nikolić, Milka; Popović, Svetozar; and Vŭsković, Leposava, "Argon Metastable and Resonant Level Densities in Ar and Ar/Cl² Discharges Used for the Processing of Bulk Niobium" (2019). Physics Faculty Publications. 398.
https://digitalcommons.odu.edu/physics_fac_pubs/398
Comments
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Journal of Applied Physics, Volume 126, Issue 10, and may be found at: https://doi.org/10.1063/1.5115043.