The effect of shaping on Reversed Field Pinch dynamics

Reversed Field Pinch fusion devices (RFPs) are inevitably plagued by magnetohydrodynamic (MHD) instabilities. High resolution numerical simulations of fully nonlinear visco-resistive magnetohydrodynamics using a Fourier pseudo-spectral method with volume penalization [Morales et al. JCP, 2014] are performed. Results of RFP simulations in toroidal geometry were reported in [Morales et al. PPCF, 2014]. Here we consider a cylindrical domain with elliptical cross-section for different aspect ratios. The results illustrate a notable influence of the shape of the cross-section on the nonlinear dynamics of RFPs. The axial mode-spectrum is qualitatively changed in cylinders with elliptic cross-section. The results suggest that shaping could change, and possibly improve the confinement of RFPs. It is certainly possible that specific helical modes can be promoted, approaching thereby a QSH state.