Plasmadynamic hypervelocity dust injector for the national spherical torus experiment

The design and construction of a plasmadynamic device to accelerate dust to hypervelocities is presented. High speed dust will be used to measure magnetic field lines in the National Spherical Torus Experiment. The plasma gun produces a high density (n(e) approximate to 10(18) cm(-3)) and low temperature (a few eV) deuterium plasma, ejected by J x B forces which provide drag on the dust particles in its path. The dust will be entrained by the plasma to velocities of 1 -30 km/s, depending on the dust mass. Carbon dust particles will be used, with diameters from 1 to 50 mu m. The key components of the plasmadynamic accelerator are a coaxial plasma gun operated at 10 kV (with an estimated discharge current of 200 kA), a dust dispenser activated by a piezoelectric transducer, and power and remote-control systems. (c) 2006 American Institute of Physics.