Numerical simulation of a compact torus initiated dense plasma focus (CT-DPF)

Summary form only given, as follows. The Phillips Laboratory has been involved in the computational and experimental investigation of compact toroid formation and acceleration. Recently, effort has been directed toward using a compact torus as the driver for a dense plasma focus. In the typical Fillipov and Mather type prefill DPFs, insulator-initiated discharges have been limited to approximately one megajoule levels by insulator restrike, erosion, or strength issues. Gas-puff, coaxial DPFs mitigate this problem at the expense of performance. An alternative, explored here, is the use of a compact plasma torus as the initiator of the DPF discharge (CT-DPF). The CT-DPF takes advantage of the stable plasma-flow-switch capabilities of the compact torus. Compact toroids have been generated and accelerated (numerically as well as experimentally) to tens of centimeters per microsecond. This provides for rapid transfer of multi-megamperes of current to the DPF load, which is placed at the end of the acceleration region, in tenths of a microsecond. This paper describes the numerical simulations which have been performed to predict CT-DPF performance in support of our experimental program. The simulations were conducted using the Phillips Laboratory´s Mach2 code, a 2 1/2-dimension Arbitrary Eulerian-Lagrangian MHD code. Argon and neon plasmas are investigated with various target densities and bank energies. Performance is assessed in terms of density and temperature increases along the focus centerline as well as implosion velocities.