Effects Of Acceleration Discharge On Compact Toroid Formation

The Phillips Laboratory's MARAUDER Compact Toroid acceleration experiments are described. The acceleration discharge is the second stage of a two-stage co-axial plasma gun discharge. The first stage discharge forms a compact torus. First stage discharge parameters are 110 microfarad, 60 to 80 kv initial voltage, 40 nanohenry initial inductance, 6 milliohm series resistance, 2 to 2.6 Megamps peak current, 1 to 2 milligrams initial gas mass (puff injected), 0.1 Tesla initial radial field (double solenoid injected). Second stage discharge parameters are 108 microfarad, 40 to 80 kv initial voltage, 25 nanohenry initial inductance. The two-stage gun geometry parameters are 44.8 cm inner conductor radius, 52.4 cm first stage outer conductor radius, 62.8 cm second stage outer conductor radius, transition from first stage to second stage at 20 cm axial distance downstream from gas injection plane, and variable (up to 80 cm) axial length of second stage. Data from fast photography, arrays of radial, azimuthal, and axial magnetic probes, He-Ne and microwave interferometry, time resolved optical spectroscopy, time gated and spectral line filtered photography, and X-ray detectors will be presented and discussed. The acceleration discharge appears to sharpen and strengthen radial magnetic field reversals, suggesting driven reconnection. The effects of varying the second stage geometry on acceleration discharge current delivery will be discussed.