First application of a digital mirror Langmuir probe for real-time plasma diagnosis
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21ja093_full.pdf
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3.79 MB
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Checksum (MD5)
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Author(s)
McCarthy, William
Golfinopoulos, T.
Woller, K.B.
Vincent, C.
Kuang, Adam Q.
Labombard, Brian
Date Issued
October 2021
Journal
Review of Scientific Instruments
Publisher
AIP
Abstract
For the first time, a digital Mirror Langmuir probe (MLP) has successfully sampled plasma temperature, ion saturation current, and floating potential together on a single probe tip in real time in a radio-frequency driven helicon linear plasma device. This is accomplished by feedback control of the bias sweep to ensure a good fit to I-V characteristics with a high frequency, high power digital amplifier and field-programmable gate array (FPGA) controller. Measurements taken by the MLP were validated by a low speed I-V characteristic manually collected during static plasma conditions. Plasma fluctuations, induced by varying the axial magnetic field (f̃ = 10 Hz), were also successfully monitored with the MLP. Further refinement of the digital MLP pushes it towards a turn-key system that minimizes the time to deployment and lessens the learning curve, positioning the digital MLP as a capable diagnostic for the study of low radio-frequency plasma physics. These demonstrations bolster confidence in fielding such digital MLP diagnostics in magnetic confinement experiments with high spatial and adequate temporal resolution such as edge plasma, scrape-off layer, and divertor probes.
Description
Submitted for publication in Review of Scientific Instruments
MIT Department
Massachusetts Institute of Technology. Plasma Science and Fusion Center
Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1063/5.0057318
