Study of MHD instability in WHAM by imposed Flow Shear

Axisymmetric magnetic mirrors are attractive for their high beta, turbulence-free radial transport, and engineering simplicity. However, MHD interchange instability due to curvature drift is known to result in flat-lining of pressure accumulation or rapid loss of stored energy. Radially sheared azimuthal flow has been used to stabilize MHD activity in other experiments including GDT and Gamma-10. This poster shows initial results from biased shear flow experiments in WHAM. Up to 1kA can be driven at up to 2.5 kV, and the radial potential profile can be experimentally manipulated with ten equally spaced concentric rings. Plasma fluctuations will be measured by a ring of floating potential probes, D-alpha bolometers, AXUV diodes, B-dot probes, and diamagnetic flux loops. Experimental observations will be compared to linear stability estimates in FLORA and non-linear simulation in VPIC.