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First application of a digital mirror Langmuir probe for real-time plasma diagnosis

Journal Article · · Review of Scientific Instruments
DOI:https://doi.org/10.1063/5.0057318· OSTI ID:1897192
 [1];  [2];  [2];  [3];  [2];  [2]
  1. Massachusetts Institute of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; OSTI
  2. Massachusetts Institute of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
  3. United Kingdom Atomic Energy Authority, Culham Science Centre, Abingdon (United Kingdom)
+ Show Author Affiliations

We report 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 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($$\widetilde{f}$$ = 10 Hz), were also successfully monitored with the MLP. Further refinement of the digital MLP pushes it toward 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.

Research Organization:
Massachusetts Institute of Technology (MIT), Cambridge, MA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Grant/Contract Number:
SC0014264
OSTI ID:
1897192
Alternate ID(s):
OSTI ID: 1825100
Journal Information:
Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 92; ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English

References (7)

Mirror Langmuir probe: A technique for real-time measurement of magnetized plasma conditions using a single Langmuir electrode journal July 2007
An experiment on the dynamics of ion implantation and sputtering of surfaces journal February 2014
New insights on boundary plasma turbulence and the quasi-coherent mode in Alcator C-Mod using a Mirror Langmuir Probe journal May 2014
The digital mirror Langmuir probe: Field programmable gate array implementation of real-time Langmuir probe biasing journal August 2019
Effect of bias on trapping probes and bolometers for Tokamak edge diagnosis journal June 1982
Principles of Plasma Diagnostics: Second Edition journal November 2002
The Plasma Boundary of Magnetic Fusion Devices book January 2000

Figures / Tables (7)

FIG. 1(p. 3)figure FIG. 1
FIG. 2(p. 3)figure FIG. 2
FIG. 3(p. 4)figure FIG. 3
FIG. 4(p. 5)figure FIG. 4
FIG. 5(p. 5)figure FIG. 5
FIG. 6(p. 6)figure FIG. 6
FIG. 7(p. 6)figure FIG. 7

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