Oblique dipole rotator to emulate a pulsar wind

We are building a dipolar rotating magnetic field (RMF) system to emulate the magnetosphere of an obliquely rotating pulsar and demonstrate production of an outgoing plasma wind. We intend to form a striped plasma wind similar to that surrounding a neutron star and potentially to observe magnetic reconnection within the stripes. The driver will consist of an orthogonal pair of Helmholtz-like drive coils powered by IGBT H-bridges producing 5 kA per turn on each coil generating ~10 G of magnetic field half a meter away from the center of the coils. The coils will be placed at atmospheric pressure in an alumina-coated fiberglass pressure vessel within the high-vacuum plasma chamber. Fuel gas will be puffed from outlets on the surface of the vessel, and the RMF will ionize the gas, hydrogen, helium and deuterium being possible fuel options. Experimental hardware is in development. Fueling system is currently being tested to ensure that the driver receives enough neutral gas to ionize and form a plasma, while additional plasmas sources are also being considered. Diagnostics will consist of an existing magnetic Hall probe array and a triple-Langmuir-Mach probe array currently being manufactured. Key next steps are to test the new solid-state RMF drivers at full power, to implement the fueling system, and to test plasma production in a cylindrical vacuum chamber, with plasma experiments on the Big Red Ball with spherical geometry and edge magnetic confinement as a longer-term objective.

*Grant acknowledgement: This work and the WiPPL Collaborative Research Facility is supported by the U.S. Department of Energy grant DE-SC0018266.