Abstract
We have developed the design of Thor: a pulsed power accelerator that delivers a precisely shaped current pulse with a peak value as high as 7 MA to a strip-line load. The peak magnetic pressure achieved within a 1-cm-wide load is as high as 100 GPa. Thor is powered by as many as 288 decoupled and transit-time isolated bricks. Each brick consists of a single switch and two capacitors connected electrically in series. The bricks can be individually triggered to achieve a high degree of current pulse tailoring. Because the accelerator is impedance matched throughout, capacitor energy is delivered to the strip-line load with an efficiency as high as 50%. We used an iterative finite element method (FEM), circuit, and magnetohydrodynamic simulations to develop an optimized accelerator design. When powered by 96 bricks, Thor delivers as much as 4.1 MA to a load, and achieves peak magnetic pressures as high as 65 GPa. When powered by 288 bricks, Thor delivers as much as 6.9 MA to a load, and achieves magnetic pressures as high as 170 GPa. We have developed an algebraic calculational procedure that uses the single brick basis function to determine the brick-triggering sequence necessary to generate a highly tailored current pulse time history for shockless loading of samples. Thor will drive a wide variety of magnetically driven shockless ramp compression, shockless flyer plate, shock-ramp, equation of state, material strength, phase transition, and other advanced material physics experiments.
Highlights
INTRODUCTIONTo generate a magnetic pressure of 100 GPa on the surface of a conductor requires a 500-T magnetic field
To generate a magnetic pressure of 100 GPa on the surface of a conductor requires a 500-T magnetic field. Such a field is generated by a linear current density of 400 MA=m
In this article we describe the design of Thor, a nextgeneration pulsed power accelerator that achieves pressures as high as 100 GPa
Summary
To generate a magnetic pressure of 100 GPa on the surface of a conductor requires a 500-T magnetic field. The first use of such current densities to generate magnetic pressures to drive material-physics experiments is described in the literature [1,2]. This magnetically driven technique was developed on the Z accelerator at Sandia National Laboratories. They are low inductance designs that transfer current to strip-line loads to maximize magnetic pressure. As of this writing, machines such as GEPI and Veloce produce currents of 3–4 MA over a near linear rise time of approximately 500 ns [5,6].
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