An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor
Abstract
Parallel heat flux calculations at the JET divertor have been based on the assumption that all incoming heat is due to the projection of the heat flux parallel to the magnetic line, q∥, plus a constant background. This simplification led to inconsistencies during the analysis of a series of dedicated tungsten melting experiments performed in 2013, for which infrared (IR) thermography surface measurements could not be recreated through simulations unless the parallel heat flux was reduced by 80% for L-mode and 60% for H-mode. We give an explanation for these differences using a new IR inverse analysis code, a set of geometrical corrections, and most importantly an additional term for the divertor heat flux accounting for non-parallel effects such as cross-field transport, recycled neutrals or charge exchange. This component has been evaluated comparing four different geometries with impinging angles varying from 2 to 90°. Its magnitude corresponds to 1.2%–1.9% of q∥, but because it is not affected by the magnetic projection, it accounts for up to 20%–30% of the tile surface heat flux. The geometrical corrections imply a further reduction of 24% of the measured heat flux. In addition, the application of the new inverse code increases the accuracy ofmore »
- Authors:
-
[2];
[3];
[8];
- Culham Science Centre (CSC), Abingdon (United Kingdom of Great Britain)
- Forschungszentrum Julich GmbH, Julich (Germany)
- ITER Organization, St. Paul Lez Durance Cedex (France)
- CEA, IRFM, Saint-Paul-Lez-Durance (France)
- Institute of Plasma Physics CAS, Praha (Czech Republic)
- Aix-Marseille Univ., Marseille (France)
- Culham Science Centre, Abingdon (United Kingdom of Great Britain); Ecole Royale Militaire/Koninklijke Militaire School, Brussels (Belgium)
- Max-Planck-Institut fur Plasmaphysik, Garching (Germany)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Publication Date:
- Research Org.:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- USDOE
- Contributing Org.:
- JET contributors
- OSTI Identifier:
- 1470941
- Grant/Contract Number:
- 633053
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Nuclear Fusion
- Additional Journal Information:
- Journal Volume: 58; Journal Issue: 10; Journal ID: ISSN 0029-5515
- Publisher:
- IOP Science
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; JET; divertor; parallel heat flux; optical projection; ITER-like wall
Citation Formats
Iglesias, Daniel, Bunting, P., Coenen, J. W., Matthews, G. F., Pitts, R. A., Silburn, S., Balboa, I., Coffey, I., Corre, Y., Dejarnac, R., Gaspar, J., Gauthier, E., Jachmich, S., Krieger, K., Pamela, S., Riccardo, V., and Stamp, M. An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor. United States: N. p., 2018.
Web. doi:10.1088/1741-4326/aad83e.
Iglesias, Daniel, Bunting, P., Coenen, J. W., Matthews, G. F., Pitts, R. A., Silburn, S., Balboa, I., Coffey, I., Corre, Y., Dejarnac, R., Gaspar, J., Gauthier, E., Jachmich, S., Krieger, K., Pamela, S., Riccardo, V., & Stamp, M. An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor. United States. https://doi.org/10.1088/1741-4326/aad83e
Iglesias, Daniel, Bunting, P., Coenen, J. W., Matthews, G. F., Pitts, R. A., Silburn, S., Balboa, I., Coffey, I., Corre, Y., Dejarnac, R., Gaspar, J., Gauthier, E., Jachmich, S., Krieger, K., Pamela, S., Riccardo, V., and Stamp, M. Thu .
"An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor". United States. https://doi.org/10.1088/1741-4326/aad83e. https://www.osti.gov/servlets/purl/1470941.
@article{osti_1470941,
title = {An improved model for the accurate calculation of parallel heat fluxes at the JET bulk tungsten outer divertor},
author = {Iglesias, Daniel and Bunting, P. and Coenen, J. W. and Matthews, G. F. and Pitts, R. A. and Silburn, S. and Balboa, I. and Coffey, I. and Corre, Y. and Dejarnac, R. and Gaspar, J. and Gauthier, E. and Jachmich, S. and Krieger, K. and Pamela, S. and Riccardo, V. and Stamp, M.},
abstractNote = {Parallel heat flux calculations at the JET divertor have been based on the assumption that all incoming heat is due to the projection of the heat flux parallel to the magnetic line, q∥, plus a constant background. This simplification led to inconsistencies during the analysis of a series of dedicated tungsten melting experiments performed in 2013, for which infrared (IR) thermography surface measurements could not be recreated through simulations unless the parallel heat flux was reduced by 80% for L-mode and 60% for H-mode. We give an explanation for these differences using a new IR inverse analysis code, a set of geometrical corrections, and most importantly an additional term for the divertor heat flux accounting for non-parallel effects such as cross-field transport, recycled neutrals or charge exchange. This component has been evaluated comparing four different geometries with impinging angles varying from 2 to 90°. Its magnitude corresponds to 1.2%–1.9% of q∥, but because it is not affected by the magnetic projection, it accounts for up to 20%–30% of the tile surface heat flux. The geometrical corrections imply a further reduction of 24% of the measured heat flux. In addition, the application of the new inverse code increases the accuracy of the tile heat flux calculation, eliminating any previous discrepancy. The parallel heat flux computed with this new model is actually much lower than previously deduced by inverse analysis of IR temperatures—40% for L-mode and 50% for H-mode—while being independent of the geometry on which it is measured. This main result confirms the validity of the optical projection as long as a non-constant and non-parallel component is considered. For a given total heating power, the model predicts over 10% reduction of the maximum tile surface heat flux compared to strict optical modelling, as well as a 30% reduced sensitivity to manufacturing and assembling tolerances. Furthermore these conclusions, along with the improvement in the predictability of the divertor thermal behaviour, are critical for JET future DT operations, and are also directly applicable to the design of the ITER divertor monoblocks.},
doi = {10.1088/1741-4326/aad83e},
journal = {Nuclear Fusion},
number = 10,
volume = 58,
place = {United States},
year = {Thu Aug 30 00:00:00 EDT 2018},
month = {Thu Aug 30 00:00:00 EDT 2018}
}
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