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Title: A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch

Abstract

A 40-channel capacitive probe has been developed to measure the electrostatic fluctuations associated with the tearing modes deep into Madison Symmetric Torus (MST) reversed field pinch plasma. The capacitive probe measures the ac component of the plasma potential via the voltage induced on stainless steel electrodes capacitively coupled with the plasma through a thin annular layer of boron nitride (BN) dielectric (also serves as the particle shield). When bombarded by the plasma electrons, BN provides a sufficiently large secondary electron emission for the induced voltage to be very close to the plasma potential. The probe consists of four stalks each with ten cylindrical capacitors that are radially separated by 1.5 cm. The four stalks are arranged on a 1.3 cm square grid so that at each radial position, there are four electrodes forming a square grid. Every two adjacent radial sets of four electrodes form a cube. The fluctuating electric field can be calculated by the gradient of the plasma potential fluctuations at the eight corners of the cube. The probe can be inserted up to 15 cm (r/a = 0.7) into the plasma. Furthermore, the capacitive probe has a frequency bandwidth from 13 Hz to 100 kHz, amplifier-circuit limit,more » sufficient for studying the tearing modes (5-30 kHz) in the MST reversed-field pinch.« less

Authors:
 [1];  [2];  [2];  [2];  [3];  [4];  [2];  [2];  [1]; ORCiD logo [1]
  1. Univ. of Science and Technology of China, Hefei (People's Republic of China)
  2. Univ. of Wisconsin, Madison, WI (United States)
  3. Univ. of Michigan, Ann Arbor, MI (United States)
  4. Univ. of Science and Technology of China, Hefei (People's Republic of China); Univ. of California, Los Angeles, CA (United States)
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
OSTI Identifier:
1466044
Alternate Identifier(s):
OSTI ID: 1349337
Grant/Contract Number:  
FC02-05ER54814
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 88; Journal Issue: 2; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Tan, Mingsheng, Stone, Douglas R., Triana, Joseph C., Almagri, Abdulgader F., Fiksel, Gennady, Ding, Weixing, Sarff, John S., McCollam, Karsten J., Li, Hong, and Liu, Wandong. A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch. United States: N. p., 2017. Web. doi:10.1063/1.4975095.
Tan, Mingsheng, Stone, Douglas R., Triana, Joseph C., Almagri, Abdulgader F., Fiksel, Gennady, Ding, Weixing, Sarff, John S., McCollam, Karsten J., Li, Hong, & Liu, Wandong. A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch. United States. doi:10.1063/1.4975095.
Tan, Mingsheng, Stone, Douglas R., Triana, Joseph C., Almagri, Abdulgader F., Fiksel, Gennady, Ding, Weixing, Sarff, John S., McCollam, Karsten J., Li, Hong, and Liu, Wandong. Wed . "A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch". United States. doi:10.1063/1.4975095. https://www.osti.gov/servlets/purl/1466044.
@article{osti_1466044,
title = {A multi-channel capacitive probe for electrostatic fluctuation measurement in the Madison Symmetric Torus reversed field pinch},
author = {Tan, Mingsheng and Stone, Douglas R. and Triana, Joseph C. and Almagri, Abdulgader F. and Fiksel, Gennady and Ding, Weixing and Sarff, John S. and McCollam, Karsten J. and Li, Hong and Liu, Wandong},
abstractNote = {A 40-channel capacitive probe has been developed to measure the electrostatic fluctuations associated with the tearing modes deep into Madison Symmetric Torus (MST) reversed field pinch plasma. The capacitive probe measures the ac component of the plasma potential via the voltage induced on stainless steel electrodes capacitively coupled with the plasma through a thin annular layer of boron nitride (BN) dielectric (also serves as the particle shield). When bombarded by the plasma electrons, BN provides a sufficiently large secondary electron emission for the induced voltage to be very close to the plasma potential. The probe consists of four stalks each with ten cylindrical capacitors that are radially separated by 1.5 cm. The four stalks are arranged on a 1.3 cm square grid so that at each radial position, there are four electrodes forming a square grid. Every two adjacent radial sets of four electrodes form a cube. The fluctuating electric field can be calculated by the gradient of the plasma potential fluctuations at the eight corners of the cube. The probe can be inserted up to 15 cm (r/a = 0.7) into the plasma. Furthermore, the capacitive probe has a frequency bandwidth from 13 Hz to 100 kHz, amplifier-circuit limit, sufficient for studying the tearing modes (5-30 kHz) in the MST reversed-field pinch.},
doi = {10.1063/1.4975095},
journal = {Review of Scientific Instruments},
number = 2,
volume = 88,
place = {United States},
year = {Wed Feb 08 00:00:00 EST 2017},
month = {Wed Feb 08 00:00:00 EST 2017}
}

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Works referenced in this record:

Time-Resolved Observation of Discrete and Continuous Magnetohydrodynamic Dynamo in the Reversed-Field Pinch Edge
journal, August 1994