Simulating the Filamentation Instability in Dense Plasma Focus
Abstract
A dense plasma focus (DPF) is an open-ended coaxial plasma gun designed to accelerate a plasma discharge down the length of the coax terminating in a Z-pinch configuration on axis. The plasma on axis goes rapidly unstable and can produce a short, intense pulse of neutrons and x-rays when deuterium is used as the working gas. The neutron yield scales strongly with the pinch current. A poor breakdown/lift-off of the plasma along the insulator can lead to current restrikes, diverting current away from the pinch and decreasing the yield. One possible cause of a poor sweep-up of the gas along the insulator is the electro-thermal instability, which can cause the plasma to breakup into individual filaments during the breakdown/lift-off stage. Plasma filamentation has recently been observed in experiments a small-scale (100J) DPF at LLNL. In this work, the filamentation instability during the lift-off stage of a DPF is studied using an extended-magnetohydrodynamic (MHD) model. The filamentation instability wavevector is along the magnetic field. 2D simulations in the R- plane are presented. The results are compared with data from the aforementioned experiments.
*Work supported by a US Department of Energy under contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (18-ERD-007). LLNL-ABS-779970.- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..DPPJ10092A