The Impact of Anomalous Resistivity in Vacuum Contaminant Plasmas on the Electrothermal Instability
- Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)
This manuscript presents an assessment of the electrothermal instability (ETI) in the presence of anomalous resistivity (AR) in vacuum contaminant plasmas (VCP) when applied to a magnetized liner inertial fusion (MagLIF)-like load.Pulsed-power driven dielectrically coated metallic liners, like in MagLIF, experience the current-driven electrothermal instability which occurs when a material’s resistivity changes with temperature and is subject to ohmic heating. Large scale pulsed-power facilities that use magnetically insulated transmission lines (MITL) have been shown to generate low-density plasma which enters the target chamber and coalesces around the load. The low-density high-temperature vacuum contaminant plasmas (VCP) can parasitically divert current from the load through causing a short in the anode-cathode gap inside the target chamber. Resistive magnetohydrodynamic (MHD) simulations of these VCP experience unphysical runaway ohmic heating due to under predicting the resistivity by using a purely collisional resistivity model.AR provides a physics-based way to address this runaway heating through increasing the resistivity in a proportional way with the drift speed. In this work, 1D simulations probe the effect that AR in VCP has on the magnetic diffusion rate, and 2D simulations show how this effect manifests in the nonlinear striation form of the ETI for a MagLIF-like load. Beryllium and aluminum dielectrically coated liners are used for the 1D and 2D simulations in this work. The1D simulations show that a VCP causes a delay in the current delivery to the load by upwards of 8 ns at 60 ns into atypical current pulse for an 1 × 107 A scale pulsed-power accelerator. The 2D simulations show the delay observed in the 1D simulations is reduced substantially (4 ns) by 2D turbulence that disrupts the VCP layer early in time. Here, the 2Dsimulated ETI growth varies across AR models, more so for the beryllium liner than the aluminum liner because the beryllium liner shows an enhanced rate of penetration for the magnetic diffusion wave in comparison to the aluminum liner. The 2D simulations show the bulk dielectric thickness varies across AR models with the Davidson AR model beingthe largest and the Buneman AR model being the smallest, and in connection with the thickness the Rayleigh-Taylor bubble-spike distances varies correspondingly.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- AC52-07NA27344; NA0003881
- OSTI ID:
- 1784606
- Report Number(s):
- LLNL-JRNL-821711; 1033817
- Journal Information:
- Journal of High Energy Density Physics, Journal Name: Journal of High Energy Density Physics
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effect of surface roughness on phase transition timing in megaampere pulsed-power–driven exploding conductors
2D Magnetohydrodynamic Simulations of the Electrothermal Instability in Metallic Liners