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We describe the injtial experiments to study the Z-pinch-drjven hohlraum ligh-yield jnertjal confinement fusion (ICF) concept of Hammer and Porter [J. H. Hammer et al., Phys. Plasmas, 6, 2129]. We show that the relationship between measured pinch power, hohlraum temperature, and secondary hohlraum coupling ("hohlraurn energetic") is well understood from O-D semi-analytic, 2-D viewfactor, and 2-D radiation magneto-hydrodynamics models. These experiments have shown the highest x-ray powers coupled to any Z-pjnch driven secondary (2655 TW), indicating the concept could scale to fusion yields of 400 MJ. We have also developed a novel, single-sided power feed, double-pinch driven secondary that meets the pinch simultaneity requirements for polar radiation symmetry. This source wjll perrnjt investigation of the pinch power balance and hohh-aum geometry requirements for ICF reIevant secondary radiation symmetry, leading to a capsule implosion capability on the Z accelerator [R. B.Spielman. er al.. Phys. Plasmas. 5,2105Plasmas. 5, (1998].

Experimental evidence for a strong influence of the radial electric field on energy deposition into thin metal wires during their electrical explosion in vacuum is presented. Explosion of the metal wire with a positive polarity when the radial electric field "pushes" electrons into the wire results in twice as much deposited energy than with the negative polarity when the radial field "expels" electrons from the wires. Moreover, the axial structure of the deposited energy changes. This effect can be explained by the influence of radial electric field on electronic emission and on vapor breakdown along the wire surface.

In this article we present the design and test results of the most powerful, fast linear transformer driver (LTD) stage developed to date. This 1-MA LTD stage consists of 40 parallel RLC (resistor R, inductor L, and capacitor C) circuits called ''bricks'' that are triggered simultaneously; it is able to deliver $1 MA current pulse with a rise time of $100 ns into the $0:1-Ohm matched load. The electrical behavior of the stage can be predicted by using a simple RLC circuit, thus simplifying the designing of various LTD-based accelerators. Five 1-MA LTD stages assembled in series into a module have been successfully tested with both resistive and vacuum electron-beam diode loads.