Calculation of Eddy Currents In the CTH Vacuum Vessel and Coil Frame
Authors: A. Zolfaghari, A. Brooks, A. Michaels, J. Hanson, and G. Hartwell
Abstract:
Knowledge of eddy currents in the vacuum vessel
walls and nearby conducting support structures can
significantly contribute to the accuracy of
Magnetohydrodynamics (MHD) equilibrium
reconstruction in toroidal plasmas. Moreover, the
magnetic fields produced by the eddy currents could
generate error fields that may give rise to islands at
rational surfaces or cause field lines to become chaotic.
In the Compact Toroidal Hybrid (CTH) device (R0 = 0.75
m, a = 0.29 m, B ≤ 0.7 T), the primary driver of the eddy
currents during the plasma discharge is the changing flux
of the ohmic heating transformer. Electromagnetic
simulations are used to calculate eddy current paths and
profile in the vacuum vessel and in the coil frame pieces
with known time dependent currents in the ohmic heating
coils. MAXWELL and SPARK codes were used for the
Electromagnetic modeling and simulation. MAXWELL
code was used for detailed 3D finite-element analysis of
the eddy currents in the structures. SPARK code was used
to calculate the eddy currents in the structures as
modeled with shell/surface elements, with each element
representing a current loop. In both cases current
filaments representing the eddy currents were prepared
for input into VMEC code for MHD equilibrium
reconstruction of the plasma discharge.
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Submitted to: ANS, Fusion Science and Technology. Presented at: Topical Meeting on the Technology of Fusion Energy (August 27-31, 2012)
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Download PPPL-4814 (pdf 1.9 MB 4pp)
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