Computational modelling of the effect of a resistive shell on the RFX reversed field pinch experiment

Non-linear numerical simulations of a reversed field pinch (RFP) with RFX geometry are presented. Emphasis is on the probable effect of a thin (resistive) shell design on experimental operation. Calculations are performed over a range of Lundquist number S and pinch parameter Θ, with realistic geometric parameters. It is found that operation with a thin shell is likely to be characterized by an enhanced fluctuation level, increased loop voltage and generally degraded plasma performance. This conclusion is independent of the specific value of the design thin shell time constant as long as this value is significantly less than the design discharge time. Specific scalings of loop voltage with Lundquist and pinch parameter are given. Results relevant to toroidal phase locking are also reported.