ITER test blanket module error field simulation experiments at DIII-D

M.J. Schaffer, J.A. Snipes, P. Gohil, P.C. de Vries, T. E. Evans, M. E. Fenstermacher, X. Gao, A.M. Garofalo, D. A. Gates, C. M. Greenfield, W. W. Heidbrink, G.J. Kramer, R. J. La Haye, S. Liu, A. Loarte, M. F.F. Nave, T. H. Osborne, N. Oyama, J.K. Park, N. RamasubramanianH. Reimerdes, G. Saibene, Antti Salmi, K. Shinohara, D. A. Spong, W.M. Solomon, Tuomas Tala, Y. B. Zhu, J.A. Boedo, V. Chuyanov, E.J. Doyle, M. Jakubowski, H. Jhang, R. M. Nazikian, V. D. Pustovitov, O. Schmitz, R. Srinivasan, T. S. Taylor, M. R. Wade, K. I. You, L. Zeng, DIII-D Team

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    Abstract

    Experiments at DIII-D investigated the effects of magnetic error fields similar to those expected from proposed ITER test blanket modules (TBMs) containing ferromagnetic material. Studied were effects on: plasma rotation and locking, confinement, L-H transition, the H-mode pedestal, edge localized modes (ELMs) and ELM suppression by resonant magnetic perturbations, energetic particle losses, and more. The experiments used a purpose-built three-coil mock-up of two magnetized ITER TBMs in one ITER equatorial port. The largest effect was a reduction in plasma toroidal rotation velocity v across the entire radial profile by as much as Δv/v ∼ 60% via non-resonant braking. Changes to global Δn/n, Δβ/β and ΔH 98/H98 were ∼3 times smaller. These effects are stronger at higher β. Other effects were smaller. The TBM field increased sensitivity to locking by an applied known n = 1 test field in both L- and H-mode plasmas. Locked mode tolerance was completely restored in L-mode by re-adjusting the DIII-D n = 1 error field compensation system. Numerical modelling by IPEC reproduces the rotation braking and locking semi-quantitatively, and identifies plasma amplification of a few n = 1 Fourier harmonics as the main cause of braking. IPEC predicts that TBM braking in H-mode may be reduced by n = 1 control. Although extrapolation from DIII-D to ITER is still an open issue, these experiments suggest that a TBM-like error field will produce only a few potentially troublesome problems, and that they might be made acceptably small.

    Original languageEnglish
    Article number103028
    Number of pages11
    JournalNuclear Fusion
    Volume51
    Issue number10
    DOIs
    Publication statusPublished - 1 Oct 2011
    MoE publication typeNot Eligible

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    Schaffer, M. J., Snipes, J. A., Gohil, P., de Vries, P. C., Evans, T. E., Fenstermacher, M. E., Gao, X., Garofalo, A. M., Gates, D. A., Greenfield, C. M., Heidbrink, W. W., Kramer, G. J., La Haye, R. J., Liu, S., Loarte, A., Nave, M. F. F., Osborne, T. H., Oyama, N., Park, J. K., ... DIII-D Team (2011). ITER test blanket module error field simulation experiments at DIII-D. Nuclear Fusion, 51(10), [103028]. https://doi.org/10.1088/0029-5515/51/10/103028