Computational simulation of magnetic field configurations in helical magneto-cumulative generators

Abstract

Summary form only given. Helical magneto-cumulative generators (MCGs) driven by high explosive can be used to generate a few microseconds of mega-ampere current for pulsed power applications. They usually consist of a helically wound cylindrical coil surrounding a cylindrical armature. The armature is driven radially outward by the detonation of explosive inside it, reducing the inductance in the device, and creating an electromotive force on a load. Modifications to the 2-1/2 dimensional MHD code MACH2 have been made that enable it to simultaneously solve for the near-solenoidal magnetic field in the air and its diffusion into the armature. This technique has been applied to configurations of armature and slater produced by a self-consistent hydrodynamic calculation of modest resolution. In these simulations-each requiring a few hours on a 450 MHz Pentium-IT computer running NT-a coupled external circuit driven by the variation of the generator inductance self-consistently determines the changing current. The generator inductance is determined at every computational time by integration of the flux linked to the stator current. The technique will be described and results will be shown from simulations that incorporate such common MCG design techniques as varying coil pitch.