Centrifugal forces from supersonic plasma rotation can be used to augment the usual magnetic confinement of plasmas. When optimized, this "knob" results in a device that features several advantages over conventional approaches.

The idea rests on two prongs: first, centrifugal forces can be used to contain plasmas to desired regions of appropriately shaped magnetic fields; second, the accompanying large velocity shear can stabilize even MHD instabilities. If these ideas are workable, the resulting coil configuration is simple and there are no substantial plasma currents.

As far as transport goes, the velocity shear can also quell microturbulence, leading to fully classical confinement as there are no neoclassical effects. Classical parallel electron transport then determines the confinement time. These losses are minimized by a large Pastukav factor resulting from the deep centrifugal potential well. At Mach 4-5, the Lawson Criterion is accessible. We are developing the theory of this concept.

An experiment to test these ideas (Maryland Centrifugal Experiment, MCX) has been funded by DOE and is under construction at IREAP. The central goal of the MCX experiment will be to obtain MHD stability from velocity shear. Specifically, it will be determined how much, if any, toroidal field is necessary to suppress residual wobbles and convection from the interchange. Previous experiments were probably MHD convection limited and did not have a toroidal field. In addition, the MCX experiment will feature a plasma of elongation 6-8, which should reduce the interchange growth rate and so reduce Mach number requirements. The CAD picture below shows the MCX with toroidal field coils.

This research is supported by the U.S. Department of Energy.