Noninvasive THz-TDS measurements of plasma bounded and optically shielded by Hall thruster wall material

We experimentally demonstrate the capability of terahertz time-domain spectroscopy (THz-TDS) to noninvasively measure the electron density and collision frequency of plasma bounded and optically shielded by Hall thruster wall material. This paper augments the standard THz-TDS plasma diagnostic theor...

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Bibliographic Details
Published in:Plasma sources science & technology 2021-07, Vol.30 (7), p.75027
Main Authors: Brown, Nathan P, Eladl, Muhannad M, Steinberg, Adam M, Deibel, Jason A, Walker, Mitchell L R
Format: Article
Language:English
Subjects:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
boron nitride
Hall thruster
plasma diagnostics
terahertz
terahertz time-domain spectroscopy
THz-TDS
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Summary:We experimentally demonstrate the capability of terahertz time-domain spectroscopy (THz-TDS) to noninvasively measure the electron density and collision frequency of plasma bounded and optically shielded by Hall thruster wall material. This paper augments the standard THz-TDS plasma diagnostic theory to account for plasma boundaries, presents THz optical property measurements of three different wall materials (grades M, M26, and HP boron nitride composite), and provides electron density and collision frequency measurements of an inductively coupled plasma bounded and optically shielded by each wall material. We find that the electron density measurement capability is weakly impacted by the boundaries, whereas the electron collision frequency measurement capability is strongly reduced by the boundaries. Here, the bounded plasma electron density trends deviate substantially from those of the unbounded plasma.
ISSN:0963-0252
1361-6595
DOI:10.1088/1361-6595/ac12be