E.M. Hollmann et al 2008 Nucl. Fusion 48 115007 doi:10.1088/0029-5515/48/11/115007
E.M. Hollmann1, T.C. Jernigan2, P.B. Parks3, J.A. Boedo1, T.E. Evans3, M. Groth4, D.A. Humphreys3, A.N. James1, M.J. Lanctot5, D. Nishijima1, D.L. Rudakov1, H.A. Scott4, E.J. Strait3, M.A. Van Zeeland3, J.C. Wesley3, W.P. West3, W. Wu3 and J.H. Yu1
Show affiliationsImpurities (H2, D2, He, Ne or Ar) injected into steady (non-disrupting) discharges with massive gas injection (MGI) are shown to mix into the plasma core dominantly via magnetohydrodynamic activity during the plasma thermal quench (TQ). Mixing efficiencies of injected impurities into the plasma core are measured to be of order 0.05–0.4. 0D modelling of the experiments is found to reproduce observed TQ and current quench durations reasonably well (typically within ±25% or so), although shutdown onset times are underestimated (by around 2×). Preliminary 0D modelling of ITER based on DIII-D mixing efficiencies suggests that MGI will work well in ITER with regard to disruption heat load and vessel force mitigation, but may not collisionally suppress runaway electrons.
52.55.Fa Tokamaks, spherical tokamaks
52.30.Cv Magnetohydrodynamics (including electron magnetohydrodynamics)
Issue 11 (November 2008)
Received 7 May 2008, accepted for publication 2 September 2008
Published 29 September 2008
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