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Title: Comparison of cryogenic (hydrogen) and TESPEL (polystyrene) pellet particle deposition in a magnetically confined plasma

Here, a cryogenic pellet injector (PI) and tracer encapsulated solid pellet (TESPEL) injector system has been operated in combination on the stellarator TJ-II. This unique arrangement has been created by piggy-backing a TESPEL injector onto the backend of a pipe-gun–type PI. The combined injector provides a powerful new tool for comparing ablation and penetration of polystyrene TESPEL pellets and solid hydrogen pellets, as well as for contrasting subsequent pellet particle deposition and plasma perturbation under analogous plasma conditions. For instance, a significantly larger increase in plasma line-averaged electron density, and electron content, is observed after a TESPEL pellet injection compared with an equivalent cryogenic pellet injection. Moreover, for these injections from the low-magnetic-field side of the plasma cross-section, TESPEL pellets deposit electrons deeper into the plasma core than cryogenic pellets. Finally, the physics behind these observations and possible implications for pellet injection studies are discussed.
Authors:
 [1] ;  [2] ; ORCiD logo [3] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1]
  1. Center for Energy, Environmental and Technological Research (CIEMAT), Madrid (Spain). National Fusion Lab.
  2. National Inst. for Fusion Science, Toki (Japan)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Fusion and Materials for Nuclear Systems Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; 633053; ENE2013-48679-R; KEIN1102; KEIN1104; UFEX106
Type:
Accepted Manuscript
Journal Name:
Europhysics Letters
Additional Journal Information:
Journal Volume: 120; Journal Issue: 2; Journal ID: ISSN 0295-5075
Publisher:
IOP Publishing
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE; European Commission (EC); Ministry of Economy, Industry and Competitiveness (Spain); National Inst. for Fusion Science (NIFS); The National Inst. of Natural Sciences (NINS)
Contributing Orgs:
TJ-II Team
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1427621

McCarthy, K. J., Tamura, N., Combs, S. K., Panadero, N., Ascabíbar, E., Estrada, T., García, R., Hernández Sánchez, J., López Fraguas, A., Navarro, M., Pastor, I., and Soleto, A.. Comparison of cryogenic (hydrogen) and TESPEL (polystyrene) pellet particle deposition in a magnetically confined plasma. United States: N. p., Web. doi:10.1209/0295-5075/120/25001.
McCarthy, K. J., Tamura, N., Combs, S. K., Panadero, N., Ascabíbar, E., Estrada, T., García, R., Hernández Sánchez, J., López Fraguas, A., Navarro, M., Pastor, I., & Soleto, A.. Comparison of cryogenic (hydrogen) and TESPEL (polystyrene) pellet particle deposition in a magnetically confined plasma. United States. doi:10.1209/0295-5075/120/25001.
McCarthy, K. J., Tamura, N., Combs, S. K., Panadero, N., Ascabíbar, E., Estrada, T., García, R., Hernández Sánchez, J., López Fraguas, A., Navarro, M., Pastor, I., and Soleto, A.. 2018. "Comparison of cryogenic (hydrogen) and TESPEL (polystyrene) pellet particle deposition in a magnetically confined plasma". United States. doi:10.1209/0295-5075/120/25001.
@article{osti_1427621,
title = {Comparison of cryogenic (hydrogen) and TESPEL (polystyrene) pellet particle deposition in a magnetically confined plasma},
author = {McCarthy, K. J. and Tamura, N. and Combs, S. K. and Panadero, N. and Ascabíbar, E. and Estrada, T. and García, R. and Hernández Sánchez, J. and López Fraguas, A. and Navarro, M. and Pastor, I. and Soleto, A.},
abstractNote = {Here, a cryogenic pellet injector (PI) and tracer encapsulated solid pellet (TESPEL) injector system has been operated in combination on the stellarator TJ-II. This unique arrangement has been created by piggy-backing a TESPEL injector onto the backend of a pipe-gun–type PI. The combined injector provides a powerful new tool for comparing ablation and penetration of polystyrene TESPEL pellets and solid hydrogen pellets, as well as for contrasting subsequent pellet particle deposition and plasma perturbation under analogous plasma conditions. For instance, a significantly larger increase in plasma line-averaged electron density, and electron content, is observed after a TESPEL pellet injection compared with an equivalent cryogenic pellet injection. Moreover, for these injections from the low-magnetic-field side of the plasma cross-section, TESPEL pellets deposit electrons deeper into the plasma core than cryogenic pellets. Finally, the physics behind these observations and possible implications for pellet injection studies are discussed.},
doi = {10.1209/0295-5075/120/25001},
journal = {Europhysics Letters},
number = 2,
volume = 120,
place = {United States},
year = {2018},
month = {1}
}