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Wall force and toroidal rotation in disruptions

Author: H. R. Strauss
Requested Type: Consider for Invited
Submitted: 2015-01-18 01:50:07

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HRS Fusion
28 Porter Road
West Orange, NJ   07052
United States

Abstract Text:
Previous studies examined effects produced by
disruptions involving vertical displacement events (VDE).
These include asymmetric wall force [1],
toroidal rotation [2], and the relation between the toroidal current asymmetry and vertical current moment [3].
These studies involved both M3D [4] numerical simulations and analysis. Here the comparison of theory and simulation is improved by examining the scaling with magnetic perturbation amplitude and vertical displacement. Simulations were performed for a sequence of VDES with both upward and downward displacements.

The asymmetric wall force is calculated analytically, and it is verified numerically that wall force is proportional to the vertical current moment [5].
It is shown that the asymmetric wall force is proportional to both the vertical displacement and the
magnetic perturbation amplitude, as found previously [3].
This can explain
why the asymmetric wall force is maximum when the growth rate of the 3D MHD perturbations
is comparable to the growth rate of the vertical resistive wall instability.

A relation is derived between
magnetic field perturbation amplitude, the vertical
current moment, and the vertical displacement.
A new term, not included in previous analysis [2], demonstrates
that part of the rotation is independent of plasma beta.
The theory compares well with M3D simulations.
This yields a scaling of toroidal rotation in AVDE disruptions which
suggests that resonant wall interactions will probably not be a concern in ITER.

This work was supported by USDOE and ITER.

[1] H. Strauss, R. Paccagnella, J. Breslau, L. Sugiyama, S. Jardin,
Nucl. Fusion 53, 073018 (2013).

[2] H. Strauss, L. Sugiyama, R. Paccagnella, J. Breslau, S. Jardin,
Nucl. Fusion 54, 043017 (2014).

[3] H. R. Strauss, Phys. Plasma 21,102509 (2014).

[4] W. Park, E. Belova, G. Y. Fu, X. Tang, H. R. Strauss, L. E. Sugiyama, Phys. Plasmas 6, 1796 (1999).

[5] P. Noll et al., Proc. 19th Symposium on Fusion Technology,
Lisbon, 1996, 1, 751.

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