This work builds upon the excitement in recent years of using liquid metals to study the magnetorotational instability (MRI) and the very closely related process of magnetic field self-generation (the MHD dynamo). This is the first experiment to investigate the MRI in a plasma, the state of matter that makes up most naturally occurring accretion disks.
Plasma MRI experiments must operate in a regime in which conductivity is high, the plasma flow is strong, and the magnetic field is weak. This is opposite to that of typical plasma experiments; the vast majority of plasma experiments are strongly magnetized and have been studied because of their applicability to nuclear fusion. This is largely because the strong, externally imposed magnetic field is critical for providing the thermal insulation that allows the plasma to become hot and strongly conducting (plasma conductivity increases with plasma temperature as Te3/2). To study much astrophysical plasma phenomena, a large, sufficiently hot, unmagnetized and flowing plasma is required.
The goals of the Plasma Couette Experiment are:
- To characterize the plasma parameters (electron temperature, density, velocity) of a mostly unmagnetized, flowing plasma in multidipole confinement with electrostatic stirring
- To search for signs of the MRI and compare with theory, especially theories beyond single fluid MHD where plasma effects (compressibility, Hall effect, plasma-neutral interactions) might be important
- To explore the possibility of creating a plasma dynamo and for studying other astrophysical phenomena in which plasma flow dominates as a source of free energy for instability