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Title: High performance double-null plasmas under radiating divertor and mantle scenarios on DIII-D

Abstract

Experiments to combine a radiating divertor or mantle with high power, high βN plasma operation have successfully reduced the divertor heat flux by 40% but have also encountered several challenging problems. For example, injecting either neon or argon seed impurities have led both to significant fuel dilution of the core plasma and to the emergence of harmful tearing mode activity which compromised plasma beta and energy confinement time. Increased divertor closure ended in more effective control over the injected seed impurity inventory, although it was also observed that small radial variations in the placement of the outer separatrix strike point within the DIII-D ‘closed’ divertor could lead to clear differences in the impurity build-up inside the core plasma. Active particle pumping of argon seed impurities through the divertor leg on the high-field side of a double-null divertor configuration showed little effect on seed impurity inventory and only modest control over the deuterium fuel inventory. Normally, 80% or greater of injected argon was removed by the corresponding cryo-pump on the low-field (outboard) side of that divertor, with the remaining argon being removed by the outboard cryo-pump from the opposite divertor. For single-null divertor cases, the contribution of the inner (high-field) cryo-pumpmore » to impurity and main-ion control appears to be complicated by the levels of divertor recycling and degree of divertor detachment. In general, divertor design that impedes the escape of seed impurities, plasma shaping that allows a higher stability limit, and electron cyclotron deposition profiles that prevent tearing mode onset and impede impurity accumulation in the core are under consideration for addressing the issues presented in our work.« less

Authors:
 [1];  [2];  [1]; ORCiD logo [1];  [3];  [4];  [4];  [1];  [1];  [5];  [1];  [4]; ORCiD logo [1];  [4];  [4];  [6];  [7]
  1. General Atomics, San Diego, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Columbia Univ., New York, NY (United States)
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  5. Univ. of Wisconsin, Madison, WI (United States)
  6. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  7. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
Publication Date:
Research Org.:
General Atomics, San Diego, CA (United States); Princeton Univ., NJ (United States); Columbia Univ., New York, NY (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. of Wisconsin, Madison, WI (United States); Oak Ridge Associated Univ., Oak Ridge, TN (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24); USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1556078
Alternate Identifier(s):
OSTI ID: 1558799
Report Number(s):
[DOE-GA-54698]
[Journal ID: ISSN 0029-5515]
Grant/Contract Number:  
[FC02-04ER54698; AC02-09CH11466; FG02-04ER54761; AC52-07NA27344; SC0013911; AC05-06OR23100; NA0003525]
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
[ Journal Volume: 59; Journal Issue: 8]; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; tokamaks; tearing modes; divertors; impurity injection

Citation Formats

Petrie, T. W., Grierson, B. A., Osborne, T., Petty, C. C., Turco, F., Allen, S. L., Fenstermacher, M. E., Ferron, J. R., Guo, H., Hinson, E. T., La Haye, R. J., Lasnier, C. J., Leonard, A. W., McLean, A. G., Victor, B., Wang, H., and Watkins, J. G. High performance double-null plasmas under radiating divertor and mantle scenarios on DIII-D. United States: N. p., 2019. Web. doi:10.1088/1741-4326/ab2936.
Petrie, T. W., Grierson, B. A., Osborne, T., Petty, C. C., Turco, F., Allen, S. L., Fenstermacher, M. E., Ferron, J. R., Guo, H., Hinson, E. T., La Haye, R. J., Lasnier, C. J., Leonard, A. W., McLean, A. G., Victor, B., Wang, H., & Watkins, J. G. High performance double-null plasmas under radiating divertor and mantle scenarios on DIII-D. United States. doi:10.1088/1741-4326/ab2936.
Petrie, T. W., Grierson, B. A., Osborne, T., Petty, C. C., Turco, F., Allen, S. L., Fenstermacher, M. E., Ferron, J. R., Guo, H., Hinson, E. T., La Haye, R. J., Lasnier, C. J., Leonard, A. W., McLean, A. G., Victor, B., Wang, H., and Watkins, J. G. Tue . "High performance double-null plasmas under radiating divertor and mantle scenarios on DIII-D". United States. doi:10.1088/1741-4326/ab2936.
@article{osti_1556078,
title = {High performance double-null plasmas under radiating divertor and mantle scenarios on DIII-D},
author = {Petrie, T. W. and Grierson, B. A. and Osborne, T. and Petty, C. C. and Turco, F. and Allen, S. L. and Fenstermacher, M. E. and Ferron, J. R. and Guo, H. and Hinson, E. T. and La Haye, R. J. and Lasnier, C. J. and Leonard, A. W. and McLean, A. G. and Victor, B. and Wang, H. and Watkins, J. G.},
abstractNote = {Experiments to combine a radiating divertor or mantle with high power, high βN plasma operation have successfully reduced the divertor heat flux by 40% but have also encountered several challenging problems. For example, injecting either neon or argon seed impurities have led both to significant fuel dilution of the core plasma and to the emergence of harmful tearing mode activity which compromised plasma beta and energy confinement time. Increased divertor closure ended in more effective control over the injected seed impurity inventory, although it was also observed that small radial variations in the placement of the outer separatrix strike point within the DIII-D ‘closed’ divertor could lead to clear differences in the impurity build-up inside the core plasma. Active particle pumping of argon seed impurities through the divertor leg on the high-field side of a double-null divertor configuration showed little effect on seed impurity inventory and only modest control over the deuterium fuel inventory. Normally, 80% or greater of injected argon was removed by the corresponding cryo-pump on the low-field (outboard) side of that divertor, with the remaining argon being removed by the outboard cryo-pump from the opposite divertor. For single-null divertor cases, the contribution of the inner (high-field) cryo-pump to impurity and main-ion control appears to be complicated by the levels of divertor recycling and degree of divertor detachment. In general, divertor design that impedes the escape of seed impurities, plasma shaping that allows a higher stability limit, and electron cyclotron deposition profiles that prevent tearing mode onset and impede impurity accumulation in the core are under consideration for addressing the issues presented in our work.},
doi = {10.1088/1741-4326/ab2936},
journal = {Nuclear Fusion},
number = [8],
volume = [59],
place = {United States},
year = {2019},
month = {7}
}

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Works referenced in this record:

Impurity enrichment studies with induced scrape-off layer flow on DIII-D
journal, December 1998


Effects of impurity seeding in DIII-D radiating mantle discharges
journal, January 2002


Integrated exhaust control with divertor parameter feedback and pellet ELM pacemaking in ASDEX Upgrade
journal, March 2005


Compatibility of the radiating divertor with high performance plasmas in DIII-D
journal, June 2007


Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall
journal, September 2013


Power exhaust by SOL and pedestal radiation at ASDEX Upgrade and JET
journal, August 2017


The effect of plasma shape on H-mode pedestal characteristics on DIII-D
journal, May 2000

  • Osborne, T. H.; Ferron, J. R.; Groebner, R. J.
  • Plasma Physics and Controlled Fusion, Vol. 42, Issue 5A
  • DOI: 10.1088/0741-3335/42/5A/319

The high-βN hybrid scenario for ITER and FNSF steady-state missionsa)
journal, May 2015

  • Turco, F.; Petty, C. C.; Luce, T. C.
  • Physics of Plasmas, Vol. 22, Issue 5
  • DOI: 10.1063/1.4921161

High-beta, steady-state hybrid scenario on DIII-D
journal, December 2015


Long pulse high performance discharges in the DIII-D tokamak
journal, November 2001


Progress toward long-pulse high-performance Advanced Tokamak discharges on the DIII-D tokamak
journal, May 2001

  • Wade, M. R.; Luce, T. C.; Politzer, P. A.
  • Physics of Plasmas, Vol. 8, Issue 5
  • DOI: 10.1063/1.1355980

High-performance double-null plasmas under radiating mantle scenarios on DIII-D
journal, May 2019


Improved confinement in highly powered high performance scenarios on DIII-D
journal, June 2017


Z dependence of the core impurity transport in ASDEX Upgrade H mode discharges
journal, November 1999


Neoclassical transport of impurities in tokamak plasmas
journal, September 1981


Tungsten transport in JET H-mode plasmas in hybrid scenario, experimental observations and modelling
journal, July 2014


Impurity behaviour in the ASDEX Upgrade divertor tokamak with large area tungsten walls
journal, May 2002


Control of core argon impurity profile by ECH in KSTAR L-mode plasmas
journal, May 2015


Formation and sustainment of a low‐aspect ratio tokamak by coaxial helicity injection
journal, June 1995

  • Nelson, B. A.; Jarboe, T. R.; Martin, A. K.
  • Physics of Plasmas, Vol. 2, Issue 6
  • DOI: 10.1063/1.871258

Results from core-edge experiments in high Power, high performance plasmas on DIII-D
journal, August 2017


Global energy confinement degradation due to macroscopic phenomena in tokamaks
journal, February 1990


First scenario development with the JET new ITER-like wall
journal, December 2013


Comparison of radiating divertor behaviour in single-null and double-null plasmas in DIII-D
journal, March 2008


Impurity behaviour under puff-and-pump radiating divertor conditions
journal, May 2009


Predictive capability of MHD stability limits in high performance DIII-D discharges
journal, July 2002


    Works referencing / citing this record:

    Integrated exhaust control with divertor parameter feedback and pellet ELM pacemaking in ASDEX Upgrade
    journal, March 2005


    Compatibility of the radiating divertor with high performance plasmas in DIII-D
    journal, June 2007


    Results from core-edge experiments in high Power, high performance plasmas on DIII-D
    journal, August 2017


    Power exhaust by SOL and pedestal radiation at ASDEX Upgrade and JET
    journal, August 2017


    High-performance double-null plasmas under radiating mantle scenarios on DIII-D
    journal, May 2019


    Progress toward long-pulse high-performance Advanced Tokamak discharges on the DIII-D tokamak
    journal, May 2001

    • Wade, M. R.; Luce, T. C.; Politzer, P. A.
    • Physics of Plasmas, Vol. 8, Issue 5
    • DOI: 10.1063/1.1355980

    The high-βN hybrid scenario for ITER and FNSF steady-state missionsa)
    journal, May 2015

    • Turco, F.; Petty, C. C.; Luce, T. C.
    • Physics of Plasmas, Vol. 22, Issue 5
    • DOI: 10.1063/1.4921161

    Formation and sustainment of a low‐aspect ratio tokamak by coaxial helicity injection
    journal, June 1995

    • Nelson, B. A.; Jarboe, T. R.; Martin, A. K.
    • Physics of Plasmas, Vol. 2, Issue 6
    • DOI: 10.1063/1.871258

    Neoclassical transport of impurities in tokamak plasmas
    journal, September 1981


    Global energy confinement degradation due to macroscopic phenomena in tokamaks
    journal, February 1990


    Impurity enrichment studies with induced scrape-off layer flow on DIII-D
    journal, December 1998


    Z dependence of the core impurity transport in ASDEX Upgrade H mode discharges
    journal, November 1999


    Long pulse high performance discharges in the DIII-D tokamak
    journal, November 2001


    Effects of impurity seeding in DIII-D radiating mantle discharges
    journal, January 2002


    Predictive capability of MHD stability limits in high performance DIII-D discharges
    journal, July 2002


    Comparison of radiating divertor behaviour in single-null and double-null plasmas in DIII-D
    journal, March 2008


    Impurity behaviour under puff-and-pump radiating divertor conditions
    journal, May 2009


    Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall
    journal, September 2013


    First scenario development with the JET new ITER-like wall
    journal, December 2013


    Tungsten transport in JET H-mode plasmas in hybrid scenario, experimental observations and modelling
    journal, July 2014


    Control of core argon impurity profile by ECH in KSTAR L-mode plasmas
    journal, May 2015


    High-beta, steady-state hybrid scenario on DIII-D
    journal, December 2015


    Impurity behaviour in the ASDEX Upgrade divertor tokamak with large area tungsten walls
    journal, May 2002


    Improved confinement in highly powered high performance scenarios on DIII-D
    journal, June 2017