Access to pedestal pressure relevant to burning plasmas on the high magnetic field tokamak Alcator C-Mod

Hughes, J. W.; Snyder, P. B.; Reinke, M. L.; LaBombard, B.; Mordijck, S.; Scott, S.; Tolman, E.; Baek, S. G.; Golfinopoulos, T.; Granetz, R. S.; Greenwald, M.; Hubbard, A. E.; Marmar, E.; Rice, J. E.; White, A. E.; Whyte, D. G.; Wilks, T.; Wolfe, S.

doi:10.7910/DVN/0JOUCX

Title: Access to pedestal pressure relevant to burning plasmas on the high magnetic field tokamak Alcator C-Mod

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Abstract

Experiments on the Alcator C-Mod tokamak have utilized reactor-relevant magnetic fields to sustain substantially higher pedestal pressure than in other devices and allow close approach to the ITER H-mode baseline target pedestal pressure of 90 kPa. The EPED model, which couples the physics of transport driven by kinetic ballooning modes and MHD instabilities arising from peeling-ballooning modes, predicts the pressure profile at the onset of edge-localized modes (ELMs), and yields to lowest order a critical-βN like behavior for the pedestal: p∝Bt×Bp ( ∝Bt^2 for fixed edge q). C-Mod routinely accesses edge plasma pressure in excess of 30 kPa, often by using a high-density (ne>3×10^20 m^-3) approach to high confinement, taking advantage of a regime known as enhanced D-alpha (EDA) H-mode. In the EDA H-mode, plasma transport regulates both the pedestal profiles and the core impurity content, thus holding the pedestal stationary at just below the peeling-ballooning stability boundary. This stationary ELM-suppressed regime has approached the maximum pedestal predicted by EPED at these densities: 60 kPa. This in turn gives rise to volume-averaged core plasma pressure in excess of 0.2MPa, a world record value for a magnetic fusion device. Another approach to achieving high pressure utilizes a pedestal limited by current-drivenmore »« less

Authors:

Hughes, J. W.; Snyder, P. B.; Reinke, M. L.; LaBombard, B.; Mordijck, S.; Scott, S.; Tolman, E.; Baek, S. G.; Golfinopoulos, T.; Granetz, R. S.; Greenwald, M.; Hubbard, A. E.; Marmar, E.; Rice, J. E.; White, A. E.; Whyte, D. G.; Wilks, T.; Wolfe, S.

OSTI

Publication Date:: Wed Oct 03 04:00:00 UTC 2018

DOE Contract Number:: FC02-99ER54512; FG02-95ER54309; FC02-06ER54873; AC02-09CH11466; AC05-00OR22725; SC0007880

Research Org.:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center; General Atomics, San Diego, CA (United States); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); College of William and Mary, Williamsburg, VA (United States)

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

Subject:: 70 PLASMA PHYSICS AND FUSION TECHNOLOGY

OSTI Identifier:: 1878746

DOI:: https://doi.org/10.7910/DVN/0JOUCX

Citation Formats


                    Hughes, J. W., Snyder, P. B., Reinke, M. L., LaBombard, B., Mordijck, S., Scott, S., Tolman, E., Baek, S. G., Golfinopoulos, T., Granetz, R. S., Greenwald, M., Hubbard, A. E., Marmar, E., Rice, J. E., White, A. E., Whyte, D. G., Wilks, T., and Wolfe, S. Access to pedestal pressure relevant to burning plasmas on the high magnetic field tokamak Alcator C-Mod.  United States: N. p., 2018. 
        Web.  doi:10.7910/DVN/0JOUCX.

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                    Hughes, J. W., Snyder, P. B., Reinke, M. L., LaBombard, B., Mordijck, S., Scott, S., Tolman, E., Baek, S. G., Golfinopoulos, T., Granetz, R. S., Greenwald, M., Hubbard, A. E., Marmar, E., Rice, J. E., White, A. E., Whyte, D. G., Wilks, T., & Wolfe, S. Access to pedestal pressure relevant to burning plasmas on the high magnetic field tokamak Alcator C-Mod.  United States.  doi:https://doi.org/10.7910/DVN/0JOUCX

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                    Hughes, J. W., Snyder, P. B., Reinke, M. L., LaBombard, B., Mordijck, S., Scott, S., Tolman, E., Baek, S. G., Golfinopoulos, T., Granetz, R. S., Greenwald, M., Hubbard, A. E., Marmar, E., Rice, J. E., White, A. E., Whyte, D. G., Wilks, T., and Wolfe, S. 2018.  
"Access to pedestal pressure relevant to burning plasmas on the high magnetic field tokamak Alcator C-Mod".  United States.  doi:https://doi.org/10.7910/DVN/0JOUCX.  https://www.osti.gov/servlets/purl/1878746. Pub date:Wed Oct 03 04:00:00 UTC 2018

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@article{osti_1878746,

  title        = {Access to pedestal pressure relevant to burning plasmas on the high magnetic field tokamak Alcator C-Mod},

  author       = {Hughes, J. W. and Snyder, P. B. and Reinke, M. L. and LaBombard, B. and Mordijck, S. and Scott, S. and Tolman, E. and Baek, S. G. and Golfinopoulos, T. and Granetz, R. S. and Greenwald, M. and Hubbard, A. E. and Marmar, E. and Rice, J. E. and White, A. E. and Whyte, D. G. and Wilks, T. and Wolfe, S.},

  abstractNote = {Experiments on the Alcator C-Mod tokamak have utilized reactor-relevant magnetic fields to sustain substantially higher pedestal pressure than in other devices and allow close approach to the ITER H-mode baseline target pedestal pressure of 90 kPa. The EPED model, which couples the physics of transport driven by kinetic ballooning modes and MHD instabilities arising from peeling-ballooning modes, predicts the pressure profile at the onset of edge-localized modes (ELMs), and yields to lowest order a critical-βN like behavior for the pedestal: p∝Bt×Bp ( ∝Bt^2 for fixed edge q). C-Mod routinely accesses edge plasma pressure in excess of 30 kPa, often by using a high-density (ne>3×10^20 m^-3) approach to high confinement, taking advantage of a regime known as enhanced D-alpha (EDA) H-mode. In the EDA H-mode, plasma transport regulates both the pedestal profiles and the core impurity content, thus holding the pedestal stationary at just below the peeling-ballooning stability boundary. This stationary ELM-suppressed regime has approached the maximum pedestal predicted by EPED at these densities: 60 kPa. This in turn gives rise to volume-averaged core plasma pressure in excess of 0.2MPa, a world record value for a magnetic fusion device. Another approach to achieving high pressure utilizes a pedestal limited by current-driven modes at low collisionality, in which pressure increases with density and which allows access to a higher EPED solution, termed “super-H”. C-Mod experiments at reduced density (ne<2×10^20 m^-3) and strong plasma shaping (δ>0.5) accessed this regime, producing pedestals with pressures up to 80kPa (approximately 90% of the ITER target) and temperatures of nearly 2 keV. In a number of these hot H-modes, we observe strong edge instabilities at low toroidal mode number (n=1) when pedestal pressure approaches predicted values from EPED, showing that current-driven MHD modes can serve as a limit on the pedestal in a metal-walled tokamak at high pressure and low collisionality.},

  doi          = {10.7910/DVN/0JOUCX},

  journal      = {},

  number       = ,

  volume       = ,

  place        = {United States},

  year         = {Wed Oct 03 04:00:00 UTC 2018},

  month        = {Wed Oct 03 04:00:00 UTC 2018}

}

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DOI: https://doi.org/10.7910/DVN/0JOUCX

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Access to pedestal pressure relevant to burning plasmas on the high magnetic field tokamak Alcator C-Mod

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