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Disruption Mitigation: 3D MHD Simulations and Experimental Validation

Author: Simon Woodruff
Requested Type: Poster Only
Submitted: 2012-12-07 16:21:10

Co-authors: N. K. Hicks, D. A. Ennis, J. E. Stuber, K. McCollam, J. Titus, C. Weatherford

Contact Info:
Woodruff Scientific Inc
4000 Aurora Ave N
Seattle, WA   98103
USA

Abstract Text:
Disruption Mitigation (DM) requires: 1) early diagnosis of precursors; and, 2) methods for controlling run-away electrons, thermal- and current-quenches. For each area there are many requirements experimentally and computationally, recognized by ITER development activities [1]. Our work focuses on simulations of MHD and plasma interactions with injected matter developing modeling capabilities for ITER-relevant DM scenarios; the development of diagnostics [2] requisite for any validation activity; and, on the possible mitigation methods, consistent with priorities from ongoing ITER design review activities.

The simulation efforts currently underway* are to model the effects of the shattered pellet on MHD and it's ability to cause a rapid thermal quench. We utilize the NIMROD 3D MHD code [3], and the CORSICA [4] equilibrium code for ITER-like scenarios, including also the development of virtual diagnostics. We will report on first simulation results.

The primary diagnostic requirements for DM we aim to address are: 1) run-away electron population measurements, and beam diagnostics; 2) heat loads with narrow spatial and temporal resolution; 3) spectroscopic measurements of flows; 4) imaging bolometry. We will outline plans.

The primary DM technology that we will examine is a pellet shattering scheme in which a small pellet is accelerated to high velocities and smashed against a plate before entering the chamber as shards, gas and dust. However, other techniques are under consideration, so we will summarize the main contending technologies.

While most computational work will be carried out at WSI, a new 2000sqft facility is available for the development of diagnostics and DM technology. There, target plasma formation and basic diagnostic set (including interferometry, fast-framing cameras, internal and edge magnetic measurements) is available. We will outline plans for the utilization of this facility for technology shake-down, and initial validation.

*Work supported by ORNL under prime contract DE-AC05-00OR22725

[1] D. Rasmussen – DM topic workshop, Organizaed by the BPO, San Diego, March (2012)
[2] E. Hollmann – Private Communication October (2012)
[3] C.R. Sovinec, A.H. Glasser, D.C. Barnes, T.A. Gianakon, R.A. Nebel, S.E. Kruger, D.D. Schnack, S.J. Plimpton, A. Tarditi, M.S. Chu and the NIMROD Team, "Nonlinear Magnetohydrodynamics with High-order Finite Elements," Journal of Computational Physics, 195, 355 (2004).
[4] James A. Crotinger, et al., CORSICA: A Comprehensive Simulation of Toroidal Magnetic-Fusion Devices, Report UCRL-ID-126284, Lawrence Livermore National Laboratory, CA, April, (1997)

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