Abstract
During the startup phase of a reversed field pinch discharge (RFP), the configuration undergoes relaxation which is the dynamic process by which the configuration evolves to states near the minimum magnetic energy thus realising improved stability. A high loop voltage and a high level of level of m =1 poloidal mode activity is observed while this process occurs. After the RFP configuration is established, there is a substantial decrease in both the m = 1 activity and the loop voltage. In addition in the Extrap T1 device, under unfavourable conditions characterised by a pinch parameter {theta} less than about 1.5 at the time of reversal, the loop voltage can further increase substantially resulting in a suppressed plasma current level. Simultaneous with the loop voltage increase there is an observed increase in poloidal m = 0 mode activity. This occurs just when field reversal first is established as the surface with zero toroidal field is produced at the plasma edge. The increased loop voltage is believed to be the result of m = 0 tearing modes resonant at the reversal surface and driven by a large parallel current gradient at the edge which become particularly pathological when the {theta}, is comparatively
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Citation Formats
Drake, J R, Brzozowski, J, Mazur, S, and Nordlund, P.
MHD activity during RFP startup in Extrap T1.
Sweden: N. p.,
1993.
Web.
Drake, J R, Brzozowski, J, Mazur, S, & Nordlund, P.
MHD activity during RFP startup in Extrap T1.
Sweden.
Drake, J R, Brzozowski, J, Mazur, S, and Nordlund, P.
1993.
"MHD activity during RFP startup in Extrap T1."
Sweden.
@misc{etde_10128042,
title = {MHD activity during RFP startup in Extrap T1}
author = {Drake, J R, Brzozowski, J, Mazur, S, and Nordlund, P}
abstractNote = {During the startup phase of a reversed field pinch discharge (RFP), the configuration undergoes relaxation which is the dynamic process by which the configuration evolves to states near the minimum magnetic energy thus realising improved stability. A high loop voltage and a high level of level of m =1 poloidal mode activity is observed while this process occurs. After the RFP configuration is established, there is a substantial decrease in both the m = 1 activity and the loop voltage. In addition in the Extrap T1 device, under unfavourable conditions characterised by a pinch parameter {theta} less than about 1.5 at the time of reversal, the loop voltage can further increase substantially resulting in a suppressed plasma current level. Simultaneous with the loop voltage increase there is an observed increase in poloidal m = 0 mode activity. This occurs just when field reversal first is established as the surface with zero toroidal field is produced at the plasma edge. The increased loop voltage is believed to be the result of m = 0 tearing modes resonant at the reversal surface and driven by a large parallel current gradient at the edge which become particularly pathological when the {theta}, is comparatively low.}
place = {Sweden}
year = {1993}
month = {Apr}
}
title = {MHD activity during RFP startup in Extrap T1}
author = {Drake, J R, Brzozowski, J, Mazur, S, and Nordlund, P}
abstractNote = {During the startup phase of a reversed field pinch discharge (RFP), the configuration undergoes relaxation which is the dynamic process by which the configuration evolves to states near the minimum magnetic energy thus realising improved stability. A high loop voltage and a high level of level of m =1 poloidal mode activity is observed while this process occurs. After the RFP configuration is established, there is a substantial decrease in both the m = 1 activity and the loop voltage. In addition in the Extrap T1 device, under unfavourable conditions characterised by a pinch parameter {theta} less than about 1.5 at the time of reversal, the loop voltage can further increase substantially resulting in a suppressed plasma current level. Simultaneous with the loop voltage increase there is an observed increase in poloidal m = 0 mode activity. This occurs just when field reversal first is established as the surface with zero toroidal field is produced at the plasma edge. The increased loop voltage is believed to be the result of m = 0 tearing modes resonant at the reversal surface and driven by a large parallel current gradient at the edge which become particularly pathological when the {theta}, is comparatively low.}
place = {Sweden}
year = {1993}
month = {Apr}
}