E×B Flux Driven Detachment Bifurcation in the DIII-D Tokamak

Jaervinen, A. E.; Allen, S. L.; Eldon, D.; Fenstermacher, M. E.; Groth, M.; Hill, D. N.; Leonard, A. W.; McLean, A. G.; Porter, G. D.; Rognlien, T. D.; Samuell, C. M.; Wang, H. Q.

doi:10.1103/PhysRevLett.121.075001

Title: $E \times B$ Flux Driven Detachment Bifurcation in the DIII-D Tokamak

Journal Article · Wed Aug 01 00:00:00 EDT 2018 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.121.075001· OSTI ID:1512600

Jaervinen, A. E. ^[1]; Allen, S. L. ^[1]; Eldon, D. ^[1]; Fenstermacher, M. E. ^[1]; Groth, M. ^[1]; Hill, D. N. ^[1]; Leonard, A. W. ^[1]; McLean, A. G. ^[1]; Porter, G. D. ^[1]; Rognlien, T. D. ^[1]; Samuell, C. M. ^[1]; Wang, H. Q. ^[1]

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

A bifurcative step transition from low-density, high-temperature, attached divertor conditions to high-density, low-temperature, detached divertor conditions is experimentally observed in DIII-D tokamak plasmas as density is increased. The step transition is only observed in the high confinement mode and only when the B × ∇B drift is directed towards the divertor. Here, this work reports for the first time a theoretical explanation and numerical simulations that qualitatively reproduce this bifurcation and its dependence on the toroidal field direction. According to the model, the bifurcation is primarily driven by the interdependence of the E × B -drift fluxes, divertor electric potential structure, and divertor conditions. In the attached conditions, strong potential gradients in the low field side (LFS) divertor drive E × B -drift flux towards the high field side divertor, reinforcing low density, high temperature conditions in the LFS divertor leg. At the onset of detachment, reduction in the potential gradients in the LFS divertor leg reduce the E × B -drift flux as well, such that the divertor plasma evolves nonlinearly to high density, strongly detached conditions. Experimental estimates of the E × B -drift fluxes, based on divertor Thomson scattering measurements, and their dependence on the divertor conditions are qualitatively consistent with the numerical predictions. Finally, the implications for divertor power exhaust and detachment control in the next step fusion devices are discussed.

View Accepted Manuscript (DOE)

View Accepted Manuscript (Publisher)

Cite

Export

Save

Research Organization:: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Organization:: USDOE National Nuclear Security Administration (NNSA)

Grant/Contract Number:: AC52-07NA27344; FC02-04ER54698; 17-ERD-020

OSTI ID:: 1512600

Alternate ID(s):: OSTI ID: 1464582

Report Number(s):: LLNL-JRNL-741509; PRLTAO; 891209

Journal Information:: Physical Review Letters, Vol. 121, Issue 7; ISSN 0031-9007

Publisher:: American Physical Society (APS)Copyright Statement

Country of Publication:: United States

Language:: English

Citation Metrics:

Cited by: 47 works

Citation information provided by
Web of Science

References (20)

A quarter-century of H-mode studies Wagner, F. Plasma Physics and Controlled Fusion, Vol. 49, Issue 12B https://doi.org/10.1088/0741-3335/49/12B/S01	journal	November 2007
Thermal front analysis of detached divertors and MARFEs Hutchinson, I. H. Nuclear Fusion, Vol. 34, Issue 10 https://doi.org/10.1088/0029-5515/34/10/I04	journal	October 1994
Progress at JET in integrating ITER-relevant core and edge plasmas within the constraints of an ITER-like wall Giroud, C.; Jachmich, S.; Jacquet, P. Plasma Physics and Controlled Fusion, Vol. 57, Issue 3 https://doi.org/10.1088/0741-3335/57/3/035004	journal	February 2015
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
Sensitivity of detachment extent to magnetic configuration and external parameters Lipschultz, Bruce; Parra, Felix I.; Hutchinson, Ian H. Nuclear Fusion, Vol. 56, Issue 5 https://doi.org/10.1088/0029-5515/56/5/056007	journal	April 2016
Experimentally-based ExB drifts in the DIII-D divertor and SOL calculated from integration of Ohm's law using Thomson scattering measurements of Te and ne Stangeby, P. C.; Elder, J. D.; McLean, A. G. Nuclear Materials and Energy, Vol. 12 https://doi.org/10.1016/j.nme.2017.03.021	journal	August 2017
Electron pressure balance in the SOL through the transition to detachment McLean, A. G.; Leonard, A. W.; Makowski, M. A. Journal of Nuclear Materials, Vol. 463 https://doi.org/10.1016/j.jnucmat.2015.01.066	journal	August 2015
Model of $L$ to $H$ -Mode Transition in Tokamak Itoh, Sanae-I.; Itoh, Kimitaka Physical Review Letters, Vol. 60, Issue 22 https://doi.org/10.1103/PhysRevLett.60.2276	journal	May 1988
Calculations of energy losses due to atomic processes in tokamaks with applications to the International Thermonuclear Experimental Reactor divertor Post, D.; Abdallah, J.; Clark, R. E. H. Physics of Plasmas, Vol. 2, Issue 6 https://doi.org/10.1063/1.871257	journal	June 1995
Impurity release from low-Z materials under light particle bombardment Davis, J. W.; Haasz, A. A. Journal of Nuclear Materials, Vol. 241-243 https://doi.org/10.1016/S0022-3115(97)80029-3	journal	February 1997
Physical sputtering and reflection processes in plasma-wall interactions Eckstein, W. Journal of Nuclear Materials, Vol. 248 https://doi.org/10.1016/S0022-3115(97)00109-8	journal	September 1997
Pfirsch-Schluter currents in the JET divertor Schaffer, M. J.; Chankin, A. V.; Guo, H. Y. Nuclear Fusion, Vol. 37, Issue 1 https://doi.org/10.1088/0029-5515/37/1/I07	journal	January 1997
Partial detachment of high power discharges in ASDEX Upgrade Kallenbach, A.; Bernert, M.; Beurskens, M. Nuclear Fusion, Vol. 55, Issue 5 https://doi.org/10.1088/0029-5515/55/5/053026	journal	April 2015
Controlling marginally detached divertor plasmas Eldon, D.; Kolemen, E.; Barton, J. L. Nuclear Fusion, Vol. 57, Issue 6 https://doi.org/10.1088/1741-4326/aa6b16	journal	May 2017
Two-dimensional electric fields and drifts near the magnetic separatrix in divertor tokamaks Rognlien, T. D.; Ryutov, D. D.; Mattor, N. Physics of Plasmas, Vol. 6, Issue 5 https://doi.org/10.1063/1.873488	journal	May 1999
Divertor Physics Research on Alcator C-Mod Lipschultz, B.; LaBombard, B.; Terry, J. L. Fusion Science and Technology, Vol. 51, Issue 3 https://doi.org/10.13182/FST07-A1428	journal	April 2007
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
Impurity seeding for tokamak power exhaust: from present devices via ITER to DEMO Kallenbach, A.; Bernert, M.; Dux, R. Plasma Physics and Controlled Fusion, Vol. 55, Issue 12 https://doi.org/10.1088/0741-3335/55/12/124041	journal	November 2013
Electric field-induced plasma convection in tokamak divertors Boedo, J. A.; Schaffer, M. J.; Maingi, R. Physics of Plasmas, Vol. 7, Issue 4 https://doi.org/10.1063/1.873915	journal	April 2000
Chapter 4: Power and particle control Loarte, A.; Lipschultz, B.; Kukushkin, A. S. Nuclear Fusion, Vol. 47, Issue 6 https://doi.org/10.1088/0029-5515/47/6/S04	journal	June 2007

Cited By (5)

Neutral density estimation in the ASDEX upgrade divertor from deuterium emissivity measurements during detachment and shoulder formation Agostini, M.; Vianello, N.; Carraro, L. Plasma Physics and Controlled Fusion, Vol. 61, Issue 11 https://doi.org/10.1088/1361-6587/ab4122	journal	September 2019
DIII-D research towards establishing the scientific basis for future fusion reactors Petty, C. C. Nuclear Fusion, Vol. 59, Issue 11 https://doi.org/10.1088/1741-4326/ab024a	journal	June 2019
First experimental tests of a new small angle slot divertor on DIII-D Guo, H. Y.; Wang, H. Q.; Watkins, J. G. Nuclear Fusion, Vol. 59, Issue 8 https://doi.org/10.1088/1741-4326/ab26ee	journal	July 2019
Summary of the 27th IAEA Fusion Energy Conference in the categories of EX/W, EX/D, and ICC Ida, K. Nuclear Fusion, Vol. 59, Issue 11 https://doi.org/10.1088/1741-4326/ab3811	journal	September 2019
Divertor detachment and asymmetry in H-mode operation with an ITER-like tungsten divertor in EAST Liu, J. B.; Wang, L.; Guo, H. Y. Nuclear Fusion, Vol. 59, Issue 12 https://doi.org/10.1088/1741-4326/ab4639	journal	October 2019

Similar Records

Progress in DIII-D towards validating divertor power exhaust predictions

Journal Article · Thu Mar 12 00:00:00 EDT 2020 · Nuclear Fusion · OSTI ID:1512600

Jaervinen, A. E.; Allen, S. L.; Eldon, D.; +12 more

Impact of drifts on divertor power exhaust in DIII-D

Journal Article · Wed May 01 00:00:00 EDT 2019 · Nuclear Materials and Energy · OSTI ID:1512600

Jaervinen, A. E.; Allen, S. L.; Eldon, D.; +11 more

UEDGE-predicted impact of molecules on low-field side target detachment in DIII–D

Journal Article · Wed May 01 00:00:00 EDT 2019 · Nuclear Materials and Energy · OSTI ID:1512600

Holm, A.; Groth, M.; Rognlien, T. D.

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Title: E × B Flux Driven Detachment Bifurcation in the DIII-D Tokamak

Citation Formats

References (20)

Cited By (5)

Similar Records

Related Subjects

Title: $E \times B$ Flux Driven Detachment Bifurcation in the DIII-D Tokamak