Separating divertor closure effects on divertor detachment and pedestal shape in DIII-D

Moser, A. L.; Casali, L.; Covele, B. M.; Leonard, A. W.; McLean, A. G.; Shafer, M. W.; Wang, H. Q.; Watkins, J. G.

doi:10.1063/1.5109027

Separating divertor closure effects on divertor detachment and pedestal shape in DIII-D

Journal Article · Thu Mar 12 00:00:00 EDT 2020 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.5109027· OSTI ID:1608790

Moser, A. L. ^[1]; ^[2]; Covele, B. M. ^[2]; ^[2]; McLean, A. G. ^[3]; ^[4]; Wang, H. Q. ^[2]; Watkins, J. G. ^[5]

General Atomics, San Diego, CA (United States); General Atomics, Energy & Advanced Concepts, DIII-D
General Atomics, San Diego, CA (United States)
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Comparison between an open divertor and a more-closed divertor in DIII-D demonstrates detachment at an up to 40% lower pedestal density (n_e,ped) in the closed divertor, due to a combination of decreased fueling of the pedestal and increased dissipation in the scrape off layer (SOL) in the closed divertor, both resulting from increased neutral trapping in the divertor. Predicting whether the relationship between divertor closure and detachment will hold for an opaque SOL, in which the contribution of ionizing neutrals to fueling the pedestal is lessened, requires separating out the different mechanisms contributing to the density difference at detachment. A series of experiments on DIII-D characterizes matched discharges using various divertor configurations to isolate the effects of divertor closure. These experiments show detachment at up to 25% lower n_e,sep in the closed divertor than the open, supported by simulations showing increased neutral trapping, and hence increased dissipation, in the closed divertor. A difference in n_e,ped/n_e,sep is also seen: for matched n_e,sep, the closed divertor has up to 20% lower ne,ped, consistent with modeling showing a smaller ionization fraction inside the separatrix in this case. Understanding how these pieces fit together will help in develop of predictive models of pedestal density and detached divertors compatible with a high-performance core.

View Accepted Manuscript (DOE)

Research Organization:: General Atomics, San Diego, CA (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: FC02-04ER54698; AC52-07NA27344; AC05-00OR22725; AC04-94AL85000

OSTI ID:: 1608790

Alternate ID(s):: OSTI ID: 1604236
OSTI ID: 1648965
OSTI ID: 1778068

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 3 Vol. 27; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

References (37)

Plasma Edge Physics with B2-Eirene Schneider, R.; Bonnin, X.; Borrass, K. Contributions to Plasma Physics, Vol. 46, Issue 1-2 https://doi.org/10.1002/ctpp.200610001	journal	February 2006
Modelling the effect of divertor closure on detachment onset in DIII-D with the SOLPS code Casali, L.; Sang, C.; Moser, A. L. Contributions to Plasma Physics, Vol. 58, Issue 6-8 https://doi.org/10.1002/ctpp.201700215	journal	April 2018
Experiments and computational modeling focused on divertor and SOL optimization for advanced tokamak operation on DIII-D Allen, S. L.; Boedo, J. A.; Bozek, A. S. Journal of Nuclear Materials, Vol. 290-293 https://doi.org/10.1016/S0022-3115(00)00501-8	journal	March 2001
Role of divertor geometry on detachment in ASDEX Upgrade Schneider, R.; Bosch, H. -S; Coster, D. Journal of Nuclear Materials, Vol. 266-269 https://doi.org/10.1016/S0022-3115(98)00524-8	journal	March 1999
Role of divertor geometry on detachment and core plasma performance in JT60U Asakura, N.; Hosogane, N.; Itami, K. Journal of Nuclear Materials, Vol. 266-269 https://doi.org/10.1016/S0022-3115(98)00818-6	journal	March 1999
Pedestal fueling through interpretive analysis of measured main chamber and divertor target flux in DIII-D Leonard, A. W.; Groth, M.; Porter, G. D. Journal of Nuclear Materials, Vol. 390-391 https://doi.org/10.1016/j.jnucmat.2009.01.046	journal	June 2009
Influence of cross-field drifts and chemical sputtering on simulations of divertor particle and heat loads in ohmic and L-mode plasmas in DIII-D, AUG, and JET using UEDGE Groth, M.; Porter, G. D.; Rensink, M. E. Journal of Nuclear Materials, Vol. 415, Issue 1 https://doi.org/10.1016/j.jnucmat.2010.10.024	journal	August 2011
Consequences of a reduction of the upstream power SOL width in ITER Kukushkin, A. S.; Pacher, H. D.; Pacher, G. W. Journal of Nuclear Materials, Vol. 438 https://doi.org/10.1016/j.jnucmat.2013.01.027	journal	July 2013
Fueling with edge recycling to high-density in DIII-D Leonard, A. W.; Elder, J. D.; Canik, J. M. Journal of Nuclear Materials, Vol. 438 https://doi.org/10.1016/j.jnucmat.2013.01.037	journal	July 2013
Detailed OEDGE modeling of core-pedestal fueling in DIII-D Elder, J. D.; Lisgo, S.; Leonard, A. W. Journal of Nuclear Materials, Vol. 438 https://doi.org/10.1016/j.jnucmat.2013.01.137	journal	July 2013
Comparison of 2D simulations of detached divertor plasmas with divertor Thomson measurements in the DIII-D tokamak Rognlien, T. D.; McLean, A. G.; Fenstermacher, M. E. Nuclear Materials and Energy, Vol. 12 https://doi.org/10.1016/j.nme.2016.12.002	journal	August 2017
The effect of divertor closure on detachment onset in DIII-D Moser, A. L.; Leonard, A. W.; McLean, A. G. Nuclear Materials and Energy, Vol. 19 https://doi.org/10.1016/j.nme.2019.01.017	journal	May 2019
Initial operation of the divertor Thomson scattering diagnostic on DIII-D Carlstrom, T. N.; Hsieh, C. L.; Stockdale, R. Review of Scientific Instruments, Vol. 68, Issue 2 https://doi.org/10.1063/1.1147893	journal	February 1997
H-mode pedestal scaling in DIII-D, ASDEX Upgrade, and JET Beurskens, M. N. A.; Osborne, T. H.; Schneider, P. A. Physics of Plasmas, Vol. 18, Issue 5 https://doi.org/10.1063/1.3593008	journal	May 2011
Initial results of the high resolution edge Thomson scattering upgrade at DIII-D Eldon, D.; Bray, B. D.; Deterly, T. M. Review of Scientific Instruments, Vol. 83, Issue 10 https://doi.org/10.1063/1.4738656	journal	October 2012
Testing the role of molecular physics in dissipative divertor operations through helium plasmas at DIII-D Canik, J. M.; Briesemeister, A. R.; McLean, A. G. Physics of Plasmas, Vol. 24, Issue 5 https://doi.org/10.1063/1.4982057	journal	May 2017
Spectroscopic characterization of the DIII-D divertor Isler, R. C.; Wood, R. W.; Klepper, C. C. Physics of Plasmas, Vol. 4, Issue 2 https://doi.org/10.1063/1.872095	journal	February 1997
Characterization of the separatrix plasma parameters in DIII-D Porter, G. D.; Moller, J.; Brown, M. Physics of Plasmas, Vol. 5, Issue 5 https://doi.org/10.1063/1.872830	journal	May 1998
Reconstruction of current profile parameters and plasma shapes in tokamaks Lao, L. L.; St. John, H.; Stambaugh, R. D. Nuclear Fusion, Vol. 25, Issue 11 https://doi.org/10.1088/0029-5515/25/11/007	journal	November 1985
Recent results from divertor and scrape-off layer studies at JET Monk), JET Team (prepared by R. D. Nuclear Fusion, Vol. 39, Issue 11Y https://doi.org/10.1088/0029-5515/39/11Y/315	journal	November 1999
Radiative divertor and scrape-off layer experiments in open and baffled divertors on DIII-D Allen, S. L.; Brooks, N. H.; Bastasz, R. Nuclear Fusion, Vol. 39, Issue 11Y https://doi.org/10.1088/0029-5515/39/11Y/348	journal	November 1999
Scrape-off layer radiation and heat load to the ASDEX Upgrade LYRA divertor Kallenbach, A.; Kaufmann, M.; Coster, D. P. Nuclear Fusion, Vol. 39, Issue 7 https://doi.org/10.1088/0029-5515/39/7/307	journal	July 1999
Scaling laws for edge plasma parameters in ITER from two-dimensional edge modelling Kukushkin, A. S.; Pacher, H. D.; Pacher, G. W. Nuclear Fusion, Vol. 43, Issue 8 https://doi.org/10.1088/0029-5515/43/8/312	journal	August 2003
Comparison of H-mode barrier width with a model of neutral penetration length Groebner, R. J.; Mahdavi, M. A.; Leonard, A. W. Nuclear Fusion, Vol. 44, Issue 1 https://doi.org/10.1088/0029-5515/44/1/022	journal	December 2003
Edge profile stiffness and insensitivity of the density pedestal to neutral fuelling in Alcator C-Mod edge transport barriers Hughes, J. W.; LaBombard, B.; Terry, J. Nuclear Fusion, Vol. 47, Issue 8 https://doi.org/10.1088/0029-5515/47/8/041	journal	August 2007
Progress in the physics basis of a Fusion Nuclear Science Facility based on the Advanced Tokamak concept Garofalo, A. M.; Chan, V. S.; Canik, J. M. Nuclear Fusion, Vol. 54, Issue 7 https://doi.org/10.1088/0029-5515/54/7/073015	journal	May 2014
Identifying the location of the OMP separatrix in DIII-D using power accounting Stangeby, P. C.; Canik, J. M.; Elder, J. D. Nuclear Fusion, Vol. 55, Issue 9 https://doi.org/10.1088/0029-5515/55/9/093014	journal	August 2015
Effects of divertor geometry on tokamak plasmas Loarte, Alberto Plasma Physics and Controlled Fusion, Vol. 43, Issue 6 https://doi.org/10.1088/0741-3335/43/6/201	journal	May 2001
Poloidal distribution of recycling sources and core plasma fueling in DIII-D, ASDEX-Upgrade and JET L-mode plasmas Groth, M.; Porter, G. D.; Rognlien, T. D. Plasma Physics and Controlled Fusion, Vol. 53, Issue 12 https://doi.org/10.1088/0741-3335/53/12/124017	journal	November 2011
Plasma detachment in divertor tokamaks Leonard, A. W. Plasma Physics and Controlled Fusion, Vol. 60, Issue 4 https://doi.org/10.1088/1361-6587/aaa7a9	journal	February 2018
Strong correlation between D ₂ density and electron temperature at the target of divertors found in SOLPS analysis Stangeby, P. C.; Sang, Chaofeng Nuclear Fusion, Vol. 57, Issue 5 https://doi.org/10.1088/1741-4326/aa5e27	journal	March 2017
SOL effects on the pedestal structure in DIII-D discharges Sontag, A. C.; Chen, X.; Canik, J. Nuclear Fusion, Vol. 57, Issue 7 https://doi.org/10.1088/1741-4326/aa6cb6	journal	May 2017
Impact of divertor geometry on H-mode confinement in the JET metallic wall Joffrin, E.; Tamain, P.; Belonohy, E. Nuclear Fusion, Vol. 57, Issue 8 https://doi.org/10.1088/1741-4326/aa6e1c	journal	June 2017
Compatibility of separatrix density scaling for divertor detachment with H-mode pedestal operation in DIII-D Leonard, A. W.; McLean, A. G.; Makowski, M. A. Nuclear Fusion, Vol. 57, Issue 8 https://doi.org/10.1088/1741-4326/aa778c	journal	July 2017
Effects of divertor geometry on H-mode pedestal structure in attached and detached plasmas in the DIII-D tokamak Wang, H. Q.; Guo, H. Y.; Leonard, A. W. Nuclear Fusion, Vol. 58, Issue 9 https://doi.org/10.1088/1741-4326/aacbde	journal	July 2018
Neutral pathways and heat flux widths in vertical- and horizontal-target EDGE2D-EIRENE simulations of JET Moulton, D.; Corrigan, G.; Harrison, J. R. Nuclear Fusion, Vol. 58, Issue 9 https://doi.org/10.1088/1741-4326/aacf0f	journal	July 2018
The EIRENE and B2-EIRENE Codes Reiter, D.; Baelmans, M.; Börner, P. Fusion Science and Technology, Vol. 47, Issue 2 https://doi.org/10.13182/FST47-172	journal	February 2005

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