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Title: Fast piezoelectric valve offering controlled gas injection in magnetically confined fusion plasmas for diagnostic and fuelling purposes

Abstract

In magnetically confined fusion plasmas controlled gas injection is crucial for plasma fuelling as well as for various diagnostic applications such as active spectroscopy. In this paper, we present a new, versatile system for the injection of collimated thermal gas beams into a vacuum chamber. This system consists of a gas pressure chamber, sealed by a custom made piezo valve towards a small capillary for gas injection. The setup can directly be placed inside of the vacuum chamber of fusion devices as it is small and immune against high magnetic fields. This enables gas injection close to the plasma periphery with high duty cycles and fast switch on/off times 0.5 ms. In this work, we present the design details of this new injection system and a systematic characterization of the beam properties as well as the gas flowrates which can be accomplished. The thin and relatively short capillary yields a small divergence of the injected beam with a half opening angle of 20°. The gas box is designed for pre-fill pressures of 10 mbar up to 100 bars and makes a flowrate accessible from 10 18 part/s up to 10 23 part/s. It hence is a versatile system for both diagnostic as well as fuelling applications. Finally, the implementation of this system in ASDEX Upgrade will be described and its application for line ratio spectroscopy on helium will be demonstrated on a selected example.

Authors:
ORCiD logo [1];  [2];  [3];  [3];  [3];  [3];  [3];  [4];  [3];  [3];  [3];  [3];  [5];  [3];  [1];  [5];  [3]
  1. Max Planck Inst. for Plasma Physics, Garching (Germany); Technical Univ. of Munich, Garching (Germany). Physics Dept.
  2. Univ. of Wisconsin, Madison, WI (United States). Dept. of Engineering Physics
  3. Max Planck Inst. for Plasma Physics, Garching (Germany)
  4. Max Planck Inst. for Plasma Physics, Greifswald (Germany)
  5. Forschungszentrum Jülich (Germany). Inst. for Energy- and Climate Research
Publication Date:
Research Org.:
Univ. of Wisconsin, Madison, WI (United States); Max Planck Inst. for Plasma Physics, Garching (Germany)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); European Commission (EC)
Contributing Org.:
ASDEX Upgrade Team
OSTI Identifier:
1466256
Alternate Identifier(s):
OSTI ID: 1389657
Grant/Contract Number:  
SC0014210; SC0013911; 633053; SC00013911
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 88; Journal Issue: 3; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; vacuum chambers; tokamaks; glow discharges; charged particle spectroscopy; plasma diagnostics; cameras; plasma temperature; friction; capillary flows

Citation Formats

Griener, M., Schmitz, O., Bald, K., Bösser, D., Cavedon, M., De Marné, P., Eich, T., Fuchert, G., Herrmann, A., Kappatou, A., Lunt, T., Rohde, V., Schweer, B., Sochor, M., Stroth, U., Terra, A., and Wolfrum, E.. Fast piezoelectric valve offering controlled gas injection in magnetically confined fusion plasmas for diagnostic and fuelling purposes. United States: N. p., 2017. Web. doi:10.1063/1.4978629.
Griener, M., Schmitz, O., Bald, K., Bösser, D., Cavedon, M., De Marné, P., Eich, T., Fuchert, G., Herrmann, A., Kappatou, A., Lunt, T., Rohde, V., Schweer, B., Sochor, M., Stroth, U., Terra, A., & Wolfrum, E.. Fast piezoelectric valve offering controlled gas injection in magnetically confined fusion plasmas for diagnostic and fuelling purposes. United States. doi:10.1063/1.4978629.
Griener, M., Schmitz, O., Bald, K., Bösser, D., Cavedon, M., De Marné, P., Eich, T., Fuchert, G., Herrmann, A., Kappatou, A., Lunt, T., Rohde, V., Schweer, B., Sochor, M., Stroth, U., Terra, A., and Wolfrum, E.. Wed . "Fast piezoelectric valve offering controlled gas injection in magnetically confined fusion plasmas for diagnostic and fuelling purposes". United States. doi:10.1063/1.4978629. https://www.osti.gov/servlets/purl/1466256.
@article{osti_1466256,
title = {Fast piezoelectric valve offering controlled gas injection in magnetically confined fusion plasmas for diagnostic and fuelling purposes},
author = {Griener, M. and Schmitz, O. and Bald, K. and Bösser, D. and Cavedon, M. and De Marné, P. and Eich, T. and Fuchert, G. and Herrmann, A. and Kappatou, A. and Lunt, T. and Rohde, V. and Schweer, B. and Sochor, M. and Stroth, U. and Terra, A. and Wolfrum, E.},
abstractNote = {In magnetically confined fusion plasmas controlled gas injection is crucial for plasma fuelling as well as for various diagnostic applications such as active spectroscopy. In this paper, we present a new, versatile system for the injection of collimated thermal gas beams into a vacuum chamber. This system consists of a gas pressure chamber, sealed by a custom made piezo valve towards a small capillary for gas injection. The setup can directly be placed inside of the vacuum chamber of fusion devices as it is small and immune against high magnetic fields. This enables gas injection close to the plasma periphery with high duty cycles and fast switch on/off times ≲ 0.5 ms. In this work, we present the design details of this new injection system and a systematic characterization of the beam properties as well as the gas flowrates which can be accomplished. The thin and relatively short capillary yields a small divergence of the injected beam with a half opening angle of 20°. The gas box is designed for pre-fill pressures of 10 mbar up to 100 bars and makes a flowrate accessible from 1018 part/s up to 1023 part/s. It hence is a versatile system for both diagnostic as well as fuelling applications. Finally, the implementation of this system in ASDEX Upgrade will be described and its application for line ratio spectroscopy on helium will be demonstrated on a selected example.},
doi = {10.1063/1.4978629},
journal = {Review of Scientific Instruments},
number = 3,
volume = 88,
place = {United States},
year = {Wed Mar 29 00:00:00 EDT 2017},
month = {Wed Mar 29 00:00:00 EDT 2017}
}

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