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Title: The Digital Mirror Langmuir Probe: Field Programmable Gate Array Implementation of Real-Time Langmuir Probe Biasing

Abstract

High bandwidth, high spatial resolution measurements of electron temperature, density and plasma potential are valuable for resolving turbulence in the boundary plasma of tokamaks. While conventional Langmuir probes can provide such measurements either their temporal or spatial resolution is limited: the former by the sweep rate necessary for obtaining I-V characteristics and the latter by the need to use multiple electrodes, as is the case in triple and double probe configurations. The Mirror Langmuir Probe (MLP) bias technique overcomes these limitations by rapidly switching the voltage on a single electrode cycling between three bias states, each dynamically optimised for the local plasma conditions. The MLP system on Alcator C-Mod used analog circuitry to perform this function, measuring Te, VF, and Isat at 1.1 MSPS. Recently, a new prototype digital MLP controller has been implemented on a Red Pitaya Field Programmable Gate Array (FPGA) board which reproduces the functionality of the original controller and performs all data acquisition. There is also the potential to provide the plasma parameters externally for use with feedback control systems. The use of FPGA technology means the system is readily customisable at a fraction of the development time and implementation cost. A second Red Pitaya wasmore » used to test the MLP by simulating the current response of a physical probe using C-Mod experimental measurements. This project is available as a git repository to facilitate extensibility (e.g. real-time control outputs, more voltage states) and scalability through collaboration.« less

Authors:
; ; ; ; ; ; ; ; ;
Publication Date:
DOE Contract Number:  
SC0014264
Research Org.:
Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1886051
DOI:
https://doi.org/10.7910/DVN/NSDWFZ

Citation Formats

Vincent, C., McCarthy, W., Golfinopoulos, T., LaBombard, B., Sharples, R., Lovell, J., Naylor, G., Hall, S., Harrison, J., and Kuang, A. Q. The Digital Mirror Langmuir Probe: Field Programmable Gate Array Implementation of Real-Time Langmuir Probe Biasing. United States: N. p., 2021. Web. doi:10.7910/DVN/NSDWFZ.
Vincent, C., McCarthy, W., Golfinopoulos, T., LaBombard, B., Sharples, R., Lovell, J., Naylor, G., Hall, S., Harrison, J., & Kuang, A. Q. The Digital Mirror Langmuir Probe: Field Programmable Gate Array Implementation of Real-Time Langmuir Probe Biasing. United States. doi:https://doi.org/10.7910/DVN/NSDWFZ
Vincent, C., McCarthy, W., Golfinopoulos, T., LaBombard, B., Sharples, R., Lovell, J., Naylor, G., Hall, S., Harrison, J., and Kuang, A. Q. 2021. "The Digital Mirror Langmuir Probe: Field Programmable Gate Array Implementation of Real-Time Langmuir Probe Biasing". United States. doi:https://doi.org/10.7910/DVN/NSDWFZ. https://www.osti.gov/servlets/purl/1886051. Pub date:Mon Jun 28 00:00:00 EDT 2021
@article{osti_1886051,
title = {The Digital Mirror Langmuir Probe: Field Programmable Gate Array Implementation of Real-Time Langmuir Probe Biasing},
author = {Vincent, C. and McCarthy, W. and Golfinopoulos, T. and LaBombard, B. and Sharples, R. and Lovell, J. and Naylor, G. and Hall, S. and Harrison, J. and Kuang, A. Q.},
abstractNote = {High bandwidth, high spatial resolution measurements of electron temperature, density and plasma potential are valuable for resolving turbulence in the boundary plasma of tokamaks. While conventional Langmuir probes can provide such measurements either their temporal or spatial resolution is limited: the former by the sweep rate necessary for obtaining I-V characteristics and the latter by the need to use multiple electrodes, as is the case in triple and double probe configurations. The Mirror Langmuir Probe (MLP) bias technique overcomes these limitations by rapidly switching the voltage on a single electrode cycling between three bias states, each dynamically optimised for the local plasma conditions. The MLP system on Alcator C-Mod used analog circuitry to perform this function, measuring Te, VF, and Isat at 1.1 MSPS. Recently, a new prototype digital MLP controller has been implemented on a Red Pitaya Field Programmable Gate Array (FPGA) board which reproduces the functionality of the original controller and performs all data acquisition. There is also the potential to provide the plasma parameters externally for use with feedback control systems. The use of FPGA technology means the system is readily customisable at a fraction of the development time and implementation cost. A second Red Pitaya was used to test the MLP by simulating the current response of a physical probe using C-Mod experimental measurements. This project is available as a git repository to facilitate extensibility (e.g. real-time control outputs, more voltage states) and scalability through collaboration.},
doi = {10.7910/DVN/NSDWFZ},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2021},
month = {6}
}

Works referencing / citing this record:

The digital mirror Langmuir probe: Field programmable gate array implementation of real-time Langmuir probe biasing
journal, August 2019