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Title: Supersonic Gas Injector for Plasma Fueling in the National Spherical Torus Experiment

Abstract

A supersonic gas injector (SGI) has been developed for fueling and diagnostic applications on the National Spherical Torus Experiment (NSTX). It is comprised of a graphite converging-diverging Laval nozzle and a commercial piezoelectric gas valve mounted on a movable probe at a low-field-side midplane port location. Also mounted on the probe is a diagnostic package: a Langmuir probe, two thermocouples, and five pick-up coils for measuring toroidal, radial, vertical magnetic field components and magnetic fluctuations at the location of the SGI tip. The SGI flow rate is up to 33.25 Pa m 3/ (1.75 × 10 22 euterium particles/s), comparable to conventional NSTX gas injectors. The nozzle operates in a pulsed regime at room temperature and a reservoir gas pressure up to 665 kPa (5000 Torr). The deuterium jet Mach number of about 4 and the divergence half-angle of 5 to 25 deg have been measured in laboratory experiments simulating the NSTX environment. Reliable operation of the SGI and all mounted diagnostics at distances 0.01 to 0.20 m from the plasma separatrix has been demonstrated in NSTX experiments. The SGI has been used for fueling of ohmic and 2- to 4-MW neutral beam injection–heated L- and H-mode plasmas. Fueling efficiencymore » in the range 0.1 to 0.3 has been obtained from the plasma electron inventory analysis. In conclusion, the SGI-fueling–based plasma discharge scenarios enabling better density control have been developed.« less

Authors:
ORCiD logo [1];  [2];  [2];  [2];  [2]; ORCiD logo [2];  [2];  [3];  [2];  [2]
  1. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Univ. of Washington, Seattle, WA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1488794
Report Number(s):
[LLNL-JRNL-750482]
[Journal ID: ISSN 1536-1055; 935757]
Grant/Contract Number:  
[AC52-07NA27344]
Resource Type:
Accepted Manuscript
Journal Name:
Fusion Science and Technology
Additional Journal Information:
[ Journal Volume: 75; Journal Issue: 1]; Journal ID: ISSN 1536-1055
Publisher:
American Nuclear Society
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamak; fueling; gas injection; supersonic gas jet

Citation Formats

Soukhanovskii, V. A., Blanchard, W. R., Dong, J. K., Kaita, R., Kugel, H. W., Menard, J. E., Provost, T. J., Raman, R., Roquemore, A. L., and Sichta, P. Supersonic Gas Injector for Plasma Fueling in the National Spherical Torus Experiment. United States: N. p., 2018. Web. doi:10.1080/15361055.2018.1502034.
Soukhanovskii, V. A., Blanchard, W. R., Dong, J. K., Kaita, R., Kugel, H. W., Menard, J. E., Provost, T. J., Raman, R., Roquemore, A. L., & Sichta, P. Supersonic Gas Injector for Plasma Fueling in the National Spherical Torus Experiment. United States. doi:10.1080/15361055.2018.1502034.
Soukhanovskii, V. A., Blanchard, W. R., Dong, J. K., Kaita, R., Kugel, H. W., Menard, J. E., Provost, T. J., Raman, R., Roquemore, A. L., and Sichta, P. Mon . "Supersonic Gas Injector for Plasma Fueling in the National Spherical Torus Experiment". United States. doi:10.1080/15361055.2018.1502034. https://www.osti.gov/servlets/purl/1488794.
@article{osti_1488794,
title = {Supersonic Gas Injector for Plasma Fueling in the National Spherical Torus Experiment},
author = {Soukhanovskii, V. A. and Blanchard, W. R. and Dong, J. K. and Kaita, R. and Kugel, H. W. and Menard, J. E. and Provost, T. J. and Raman, R. and Roquemore, A. L. and Sichta, P.},
abstractNote = {A supersonic gas injector (SGI) has been developed for fueling and diagnostic applications on the National Spherical Torus Experiment (NSTX). It is comprised of a graphite converging-diverging Laval nozzle and a commercial piezoelectric gas valve mounted on a movable probe at a low-field-side midplane port location. Also mounted on the probe is a diagnostic package: a Langmuir probe, two thermocouples, and five pick-up coils for measuring toroidal, radial, vertical magnetic field components and magnetic fluctuations at the location of the SGI tip. The SGI flow rate is up to 33.25 Pa m3/ (1.75 × 1022 euterium particles/s), comparable to conventional NSTX gas injectors. The nozzle operates in a pulsed regime at room temperature and a reservoir gas pressure up to 665 kPa (5000 Torr). The deuterium jet Mach number of about 4 and the divergence half-angle of 5 to 25 deg have been measured in laboratory experiments simulating the NSTX environment. Reliable operation of the SGI and all mounted diagnostics at distances 0.01 to 0.20 m from the plasma separatrix has been demonstrated in NSTX experiments. The SGI has been used for fueling of ohmic and 2- to 4-MW neutral beam injection–heated L- and H-mode plasmas. Fueling efficiency in the range 0.1 to 0.3 has been obtained from the plasma electron inventory analysis. In conclusion, the SGI-fueling–based plasma discharge scenarios enabling better density control have been developed.},
doi = {10.1080/15361055.2018.1502034},
journal = {Fusion Science and Technology},
number = [1],
volume = [75],
place = {United States},
year = {2018},
month = {9}
}

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