[an error occurred while processing this directive] P3: MHD

WORK PLAN FOR THE MHD PHYSICS GROUP

Updated 4/10/02

 

Broad questions to be addressed:

  1. (Scientific value) What new MHD physics can we learn from a burning plasma, and to what extent will the proposed experiments allow us to investigate those physics issues?

  2. (Readiness to proceed) What limitations will MHD instabilities impose on the ability of a burning plasma experiment to achieve its full range of scientific goals, and how can the instabilities be avoided or ameliorated?

  3. (Contribution to fusion development) What impact will the MHD physics learned in a burning plasma experiment have on the development of future fusion devices — both tokamaks and other concepts?

 

Detailed physics issues and work plan:

  1. Generation of equilibria for stability studies — Initially based on "reference case" profiles for each experiment, followed by neighboring equilibria for sensitivity studies; later based on possible new transport modeling.
    — L. Lao (GA), J. Manickam (PPPL)

  2. Identification of operational ideal MHD stability boundaries — Identify the limiting instabilities and proximity of operating points to the stability limits. Assess the sensitivity of the stability properties to modest variation in plasma profiles, shaping, wall position, and edge safety factor.
    — A. Glasser (LANL), J. Manickam, (PPPL), A. Turnbull (GA)

  3. Stability limits with a resistive wall — In scenarios that rely on wall stabilization, assess the limits imposed by resistive wall modes in the presence of plasma rotation and active feedback control. What rotation rate and momentum input are required for stability?
    — M. Chu (GA), S. Sabbagh (Columbia Univ.), J. Sarff (UW)

  4. Neoclassical tearing mode threshold —Will the operating regime differ sufficiently from present experiments to provide a test of the NTM scaling with S and rho_i*? Assess the anticipated limits imposed by neoclassical tearing modes. In scenarios that exceed the estimated NTM threshold, what ECH power would be required for stabilization?
    — D. Brennan (ORISE), D. Gates (PPPL), C. Hegna (UW), R. LaHaye (GA)

  5. Error fields — Estimate the upper limit for resonant (and non-resonant?) n=1 asymmetries of the equilibrium field required for stability against locked tearing modes and resistive wall modes.
    — R. LaHaye (GA)

  6. m = 1 mode stability — In scenarios with q(0)~1, assess stability of the m=1 mode and its anticipated impact on plasma performance. What degree of stabilization is provided by alpha particles?
    — J. Breslau (PPPL), S. Jardin (PPPL), H. Strauss (NYU), L. Sugiyama (MIT)

  7. Disruption dynamics and disruption mitigation — Assess the possible electromagnetic loads due to halo currents and the anticipated multiplication factor for runaway electrons by a knock-on avalanche process during disruptions. Can a high-pressure gas jet or other method provide mitigation of disruption effects?
    — D. Humphreys (GA), S. Jardin (PPPL), R. Granetz (MIT)

  8. ELM stability — Calculate edge stability boundaries and eigenmode extent for localized intermediate wavelength external kink modes. Are the pedestal parameters consistent with MHD stability at the edge? What is the possible energy loss during an instability?
    — P. Snyder (GA), D Mossessian (MIT)

  9. Impact on fusion development — Assess the applicability of MHD physics from the proposed burning plasma experiments to future fusion devices including alternate concepts.
    — M. Ono (PPPL), J. Sarff (UW)

 

Schedule of work:

  1. Identify key MHD issues for a burning plasma experiment. (March 15)
  2. Draft background sections of report, including general discussion of key MHD issues. (due March 15)
  3. Develop a common set of profiles and equilibria as a starting point for detailed analysis. (March 20)
  4. Make a preliminary assessment of the three proposed experiments based on existing literature and analytic models. Identify areas needing further analysis. (April 1)
  5. First draft of report based on preliminary assessment. (due April 15)
  6. Present preliminary assessment at Sherwood meeting (April 22-24)
  7. Working group meeting to discuss the preliminary assessment, obtain further input, and discuss progress on detailed analysis. (April 24-25)
  8. Make an intermediate assessment of the three proposed experiments based on new analysis and community input. (May 10)
  9. Second draft of report based on additional analysis. (due May 15)
  10. Revise draft report for distribution to community (due June 1)
  11. Plan agenda for MHD group meetings at Snowmass, based on issues where discussion seems to be needed. (June 5)
  12. Meeting at Snowmass (July 8-19)