Dynamic deformation of a solenoid wire due to internal magnetic pressure, revised

Deformation of the wire used in the windings of an inertially confined (single use) solenoid used to produce a pulsed high magnetic field is potentially the limiting factor for the magnitude and duration of the magnetic field produced. The rising magnetic pressure at the wire surface becomes large enough to cause the cross section of the wire to plastically deform on a time scale shorter than the overall solenoid disassembly time. This may result in short circuiting due to insulator breakage and/or physical contact of adjacent windings. An analytic approximation modeling the deformation dynamics is presented which takes into account both inertial and material yield strength effects. The model is validated by comparison to two dimensional magnetohydrodynamic simulations of the process by Numerex´s MS Windows version of AFRL´s MACH2. Cases ranging from those where yield strength has a negligible effect on the deformation to where yield strength is significant are considered. This paper expands on work presented at the previous IEEE IPPC [E.L. Ruden et al., 2001].