Experimental evidence for MHD plasma centrifugal confinement in open magnetic field configuration

In the Maryland Centrifugal Experiment, the plasma is created in a shaped open-field magnetic configuration. Plasma rotation perpendicular to the magnetic field at supersonic speeds (sonic Mach number larger than unity) is controlled by an externally-applied E .$\times $ B drift. This work documents the centrifugal confinement effect produced by the plasma rotation from interferometric measurements of plasma density at the magnetic minimum (midplane) and 85 cm off-midplane.~~ Complete time histories of density at these two locations are obtained and compared to deduce the efficacy of axial confinement.~~ Other key parameters are also directly measured at midplane (rotation velocity profiles, ion temperature, and diamagnetic flux) and off-midplane (diamagnetic flux).~ The observed scaling of the average density ratio at midplane and off-midplane is obtained as a function of the shape of the magnetic field (mirror ratio) and the data are compared with the MHD (Grad-Shafranov equation) solution of the centrifugally confined density.~~ The theory depends on the sonic Mach number and mirror ratio and the data are shown to be in agreement with the predictions of the ideal MHD equilibrium theory.