Stabilization of tearing modes to suppress major disruptions in tokamaks

It is shown, for q-profiles which lead to a disruption, that the control of the amplitude of the 2/1-tearing-mode avoids the disruption. q-profiles measured in T-4 and PLT before a major disruption have been studied. Two methods of controlling the 2 /1-mode amplitude have been considered: 1) Feedbac...

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Bibliographic Details
Published in:Nuclear fusion 1979-10, Vol.19 (10), p.1333-1342
Main Authors: Holmes, J. A, Carreras, B, Hicks, H.R, Lynch, S.J, Waddell, B.V
Format: Article
Language:English
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Summary:It is shown, for q-profiles which lead to a disruption, that the control of the amplitude of the 2/1-tearing-mode avoids the disruption. q-profiles measured in T-4 and PLT before a major disruption have been studied. Two methods of controlling the 2 /1-mode amplitude have been considered: 1) Feedback stabilization with the feedback signal locked in phase with the 2/1 mode. The major disruption is suppressed if the feedback parameters (time delay and gain) are properly chosen. Otherwise, only a delay in the disruption is observed. 2) Heating slightly outside the q = 2 surface. Modifying the current density profile can decrease, and even eliminate, the 2/1-3/2 interaction. In this way, the disruption is avoided. In both cases it is only necessary to decrease the 2/1-mode amplitude to suppress the disruption. It is not always necessary to stabilize the unstable modes fully.
ISSN:0029-5515
1741-4326
DOI:10.1088/0029-5515/19/10/005