Experimental platforms for plasma turbulence studies at WiPPL

Both the spherical BRB device and the toroidal MST device provide opportunities for plasma turbulence experiments at the Wisconsin Plasma Physics Laboratory (WiPPL) to both internal and external users of the facility. Plasma gun arrays and compact-toroid (CT) injectors are being developed as sources to enable a variety of turbulence scenarios. In BRB, electrostatically biased plasma gun arrays produce rotating helical flux ropes along an axial magnetic field, driving magnetic relaxation and energizing what appear to be Alfvenic and ion cyclotron fluctuations observed up to frequencies of order 100 kHz. Colliding CTs with stationary grids may allow control of the injection scale for studies of magnetized plasma turbulent cascades. Colliding CTs with each other may produce shocks and turbulent structures which could generate magnetic energy or accelerate particles up to suprathermal energies. In MST, the energy input by colliding CTs or flux ropes might interact with the strong turbulent cascade produced by reversed-field pinch current relaxation.