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Title: Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements

Abstract

Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D2 molecules and the He atoms which will be produced by D-T fusion. To study He exhaust, Penning gauges were used to measure total neutral pressure assisted by spectroscopy to resolve the D and He partial pressures. In this contribution, initial results are shown from developing this technique into a miniaturized configuration for direct in-situ measurements in the divertor of fusion devices. The configuration is based off a gauge originally designed for the National Spherical Tokamak Experiment-Upgrade (NSTX-U). The goal of this new miniaturized design it to reduce the space required by the gauge on the device and use of the inherent magnetic field of the machine rather than permanent magnets inside the gauge, enabling it to be adapted into a system that can be extended directly into the divertor region. The feasibility test of the method for NSTX-U and the Wendelstein 7-X (W7-X) stellarator are surveyed. For W7-X, a commercial Penning Gauge has been installed on an outboard vacuum flange as a generic feasibility test in the neutral gas environment of amore » stellarator. At an integration time of 25s, helium lines can be seen down to 10^-5 mbar and H-alpha lines down to 10^-6 mbar. Successful measurement of the total as well as the fractional neutral pressures of He and H has been shown. A first prototype of the miniature Penning gauge has been tested in Madison and shows a near linear power law scaling between current and pressure: I = C*P^n with n = 1.0 - 1.2. Pressure measurements were achieved starting at 10^-3 mbar and down to 10^-6 mbar. A modular gauge is being assembled, which allows easy interchangeability of the anode to test new anode geometries, in order to improve optical access and increase spectroscopic sensitivity. This shall enable an increase of the time resolution of the spectroscopically assisted fractional neutral pressure measurements to up to 1kHz.« less

Authors:
; ; ; ;
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
DOE Contract Number:  
AC02-09CH11466
Product Type:
Dataset
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Penning gauge Partial pressure Helium spectroscopy
Keywords:
Penning gauge Partial pressure Helium spectroscopy
OSTI Identifier:
1367166
DOI:
10.11578/1367166

Citation Formats

Flesch, K., Kremeyer, T., Schmitz, O., Soukhanovskii, V., and Wenzel, U. Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements. United States: N. p., 2016. Web. doi:10.11578/1367166.
Flesch, K., Kremeyer, T., Schmitz, O., Soukhanovskii, V., & Wenzel, U. Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements. United States. doi:10.11578/1367166.
Flesch, K., Kremeyer, T., Schmitz, O., Soukhanovskii, V., and Wenzel, U. 2016. "Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements". United States. doi:10.11578/1367166. https://www.osti.gov/servlets/purl/1367166. Pub date:Tue Nov 01 00:00:00 EDT 2016
@article{osti_1367166,
title = {Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements},
author = {Flesch, K. and Kremeyer, T. and Schmitz, O. and Soukhanovskii, V. and Wenzel, U.},
abstractNote = {Direct measurements of the helium (He) fractional neutral pressure in the neutral gas around fusion devices is challenging because of the small mass difference between the abundant D2 molecules and the He atoms which will be produced by D-T fusion. To study He exhaust, Penning gauges were used to measure total neutral pressure assisted by spectroscopy to resolve the D and He partial pressures. In this contribution, initial results are shown from developing this technique into a miniaturized configuration for direct in-situ measurements in the divertor of fusion devices. The configuration is based off a gauge originally designed for the National Spherical Tokamak Experiment-Upgrade (NSTX-U). The goal of this new miniaturized design it to reduce the space required by the gauge on the device and use of the inherent magnetic field of the machine rather than permanent magnets inside the gauge, enabling it to be adapted into a system that can be extended directly into the divertor region. The feasibility test of the method for NSTX-U and the Wendelstein 7-X (W7-X) stellarator are surveyed. For W7-X, a commercial Penning Gauge has been installed on an outboard vacuum flange as a generic feasibility test in the neutral gas environment of a stellarator. At an integration time of 25s, helium lines can be seen down to 10^-5 mbar and H-alpha lines down to 10^-6 mbar. Successful measurement of the total as well as the fractional neutral pressures of He and H has been shown. A first prototype of the miniature Penning gauge has been tested in Madison and shows a near linear power law scaling between current and pressure: I = C*P^n with n = 1.0 - 1.2. Pressure measurements were achieved starting at 10^-3 mbar and down to 10^-6 mbar. A modular gauge is being assembled, which allows easy interchangeability of the anode to test new anode geometries, in order to improve optical access and increase spectroscopic sensitivity. This shall enable an increase of the time resolution of the spectroscopically assisted fractional neutral pressure measurements to up to 1kHz.},
doi = {10.11578/1367166},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2016},
month = {11}
}

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Works referenced in this record:

Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements
journal, August 2016

  • Flesch, K.; Kremeyer, T.; Schmitz, O.
  • Review of Scientific Instruments, Vol. 87, Issue 11
  • DOI: 10.1063/1.4960815

    Works referencing / citing this record:

    Development of miniaturized, spectroscopically assisted Penning gauges for fractional helium and hydrogen neutral pressure measurements
    journal, August 2016

    • Flesch, K.; Kremeyer, T.; Schmitz, O.
    • Review of Scientific Instruments, Vol. 87, Issue 11
    • DOI: 10.1063/1.4960815