Effects of boundary conditions on magnetic fluctuation behaviour in a RFP produced in a non-bellows metal chamber

Abstract

Reversed field pinch (RFP) plasmas are produced in a nonbellows metal chamber whose time constant is a little longer than the current rise time. With an outer copper shell, RFP configurations are sustained for a period of the shell time constant. The magnetic fluctuations are dominated by internal resonant m=1 tearing modes, with a fluctuation level of approximately 4%. When the shell is removed, the fluctuation level increases to 7-10%. The discharge resistance also increases by a factor of 2-3 with an increase in the fluctuation level.