Plasma fuelling with cryogenic pellets in the stellarator TJ-II
Abstract
Cryogenic pellet injection is a widely used technique for delivering fuel to the core of magnetically confined plasmas. Indeed, such systems are currently functioning on many tokamak, reversed field pinch and stellarator devices. A pipe-gun-type pellet injector is now operated on the TJ-II, a low-magnetic shear stellarator of the heliac type. Cryogenic hydrogen pellets, containing between 3×1018 and 4×1019 atoms, are injected at velocities between 800 and 1200 m s-1 from its low-field side into plasmas created and/or maintained in this device by electron cyclotron resonance and/or neutral beam injection heating. In this paper, the first systematic study of pellet ablation, particle deposition and fuelling efficiency is presented for TJ-II. From this, light-emission profiles from ablating pellets are found to be in reasonable agreement with simulated pellet ablation profiles (created using a neutral gas shielding-based code) for both heating scenarios. In addition, radial offsets between recorded light-emission profiles and particle deposition profiles provide evidence for rapid outward drifting of ablated material that leads to pellet particle loss from the plasma. Finally, fuelling efficiencies are documented for a range of target plasma densities (~4×1018– ~2×1019 m-3). These range from ~20%– ~85% and are determined to be sensitive to pellet penetration depth.more »
- Authors:
-
- Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Publication Date:
- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC)
- Contributing Org.:
- the TJ-II Team
- OSTI Identifier:
- 1376533
- Grant/Contract Number:
- AC05-00OR22725
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nuclear Fusion
- Additional Journal Information:
- Journal Volume: 57; Journal Issue: 5; Journal ID: ISSN 0029-5515
- Publisher:
- IOP Science
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
McCarthy, K. J., Panadero, N., Velasco, J. L., Combs, S. K., Caughman, J. B. O., Fontdecaba, J. M., Foust, C., García, R., Hernández Sánchez, J., Navarro, M., Pastor, I., and Soleto, A. Plasma fuelling with cryogenic pellets in the stellarator TJ-II. United States: N. p., 2017.
Web. doi:10.1088/1741-4326/aa64fd.
McCarthy, K. J., Panadero, N., Velasco, J. L., Combs, S. K., Caughman, J. B. O., Fontdecaba, J. M., Foust, C., García, R., Hernández Sánchez, J., Navarro, M., Pastor, I., & Soleto, A. Plasma fuelling with cryogenic pellets in the stellarator TJ-II. United States. https://doi.org/10.1088/1741-4326/aa64fd
McCarthy, K. J., Panadero, N., Velasco, J. L., Combs, S. K., Caughman, J. B. O., Fontdecaba, J. M., Foust, C., García, R., Hernández Sánchez, J., Navarro, M., Pastor, I., and Soleto, A. Tue .
"Plasma fuelling with cryogenic pellets in the stellarator TJ-II". United States. https://doi.org/10.1088/1741-4326/aa64fd. https://www.osti.gov/servlets/purl/1376533.
@article{osti_1376533,
title = {Plasma fuelling with cryogenic pellets in the stellarator TJ-II},
author = {McCarthy, K. J. and Panadero, N. and Velasco, J. L. and Combs, S. K. and Caughman, J. B. O. and Fontdecaba, J. M. and Foust, C. and García, R. and Hernández Sánchez, J. and Navarro, M. and Pastor, I. and Soleto, A.},
abstractNote = {Cryogenic pellet injection is a widely used technique for delivering fuel to the core of magnetically confined plasmas. Indeed, such systems are currently functioning on many tokamak, reversed field pinch and stellarator devices. A pipe-gun-type pellet injector is now operated on the TJ-II, a low-magnetic shear stellarator of the heliac type. Cryogenic hydrogen pellets, containing between 3×1018 and 4×1019 atoms, are injected at velocities between 800 and 1200 m s-1 from its low-field side into plasmas created and/or maintained in this device by electron cyclotron resonance and/or neutral beam injection heating. In this paper, the first systematic study of pellet ablation, particle deposition and fuelling efficiency is presented for TJ-II. From this, light-emission profiles from ablating pellets are found to be in reasonable agreement with simulated pellet ablation profiles (created using a neutral gas shielding-based code) for both heating scenarios. In addition, radial offsets between recorded light-emission profiles and particle deposition profiles provide evidence for rapid outward drifting of ablated material that leads to pellet particle loss from the plasma. Finally, fuelling efficiencies are documented for a range of target plasma densities (~4×1018– ~2×1019 m-3). These range from ~20%– ~85% and are determined to be sensitive to pellet penetration depth. Additional observations, such as enhanced core ablation, are discussed and planned future work is outlined.},
doi = {10.1088/1741-4326/aa64fd},
journal = {Nuclear Fusion},
number = 5,
volume = 57,
place = {United States},
year = {Tue Apr 04 00:00:00 EDT 2017},
month = {Tue Apr 04 00:00:00 EDT 2017}
}
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