Major Disruptions in the TOSCA Tokamak

Abstract

The major disruption has been studied in detail on the TOSCA tokamak with the use of approximate helical coils. The $m=3\mathrm{}$, $n=2\mathrm{}$ and $m=5\mathrm{}$, $n=3\mathrm{}$ modes have been clearly observed for the first time before a major disruption. The amplitude of the $m=2\mathrm{}$, $n=1\mathrm{}$ mode at the rational surface is about 4% and the $m=3\mathrm{}$, $n=2\mathrm{}$ mode amplitude ∼ 4.5% before a major disruption. When the $m=2\mathrm{}$, $n=1\mathrm{}$ and $m=3\mathrm{}$, $n=2\mathrm{}$ approximate helical coils are energized with large coil currents, a major disruption occurs.