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Recent work on the 1-MA Michigan Linear Transformer Driver, MAIZE, has focused on the Magneto Rayleigh-Taylor (MRT) instability and validation of analytic theory, developed at UM (see abstract by Lau et al.). MAIZE is a nominal 1-MA, 100 ns, 100 kV driver, capable of driving 0.1 Ω matched loads. We present here the results of a series of shots using different techniques to seed the MRT instability on planar or pseudo-planar foils. The planar geometry is unique in that it eliminates the complication of the m=0 and m=1 instabilities, allowing extricated analysis of the MRT instability.

Linear Transformer Drivers (LTDs) represent the most compact, high-current accelerators. LTDs have numerous advantages over Marx PFL systems: a) fast risetime (100 ns) without additional pulse forming, b) high efficiency (∼70%), c) inductive voltage adder and d) repetitively pulsed operation. LTDs have been utilized in a patented Sandia design for a PW pulsed power driver for fusion.[1] MYKONOS, a 1-MV, 1-MA LTD system is being constructed at Sandia. The 1-MA, 100 kV LTD at UM was designed and developed at the IHCE under Sandia sponsorship. Initial tests were performed at IHCE in an inductive-adder with 5 LTD modules at 1-MA and 0.5 MV. At UM, the LTD was coupled to a Magnetically Insulated Transmission Line (MITL) to drive a load in the MAIZE z-pinch facility. Resistive load tests agreed well with PSPICE simulations. Modifications have been made to the UM LTD to improve its serviceability in an experimental system. Magneto-Rayleigh-Taylor plasma instability experiments have been performed on the UM LTD facility in a low-inductance, planar-foil plasma load, located between two planar anode plates.[2] Laser shadowgraphy was performed by a 100-sps doubled-YAG laser. Instability growth rate have been compared to MRT theory (Lau et al., this conference). PSPICE simulations of LTD component voltages and currents have been performed, accounting for calculated foil motion. UM LTD convolute experiments were performed.[3]

Spectroscopic analysis has been performed on Al foil plasmas ablated by the Linear Transformer Driver (LTD) at the University of Michigan. The MAIZE LTD can supply 1-MA, 100 kV pulses with 100 ns risetime into a matched load. The plasma load used in this experiment consists of a 400 nm Al foil (cathode) placed between two, planar, current return anode posts. The LTD was charged to +−70 kV, resulting in approximately 0.65 MA with a 170 ns risetime passing through the foil. An optical fiber was placed about 1 cm away from the load; plasma light passed through a 0.75-m optical spectrograph and was gated for 10 ns by an intensified CCD detector.

Initial dynamic load experiments were performed on UM's 1-MA linear transformer driver (LTD) facility, MAIZE, to characterize magneto-Rayleigh-Taylor (MRT) instability growth and plasma dynamics on planar-foil plasmas. The MAIZE LTD is capable of delivering a 1-MA, < 100 ns risetime drive pulse into a 0.1 Ω matched load with a ±100 kV charge. For these dynamic load experiments the LTD was charged to ±70 kV to deliver up to 0.7 MA with a 170 ns risetime into the foil load.