Simulations of Dense Plasma Focus with Local Mass Injection*

Dense Plasma Focus (DPF) pulsed power device is a type of z-pinch used to provide short pulses of fusion or spallation neutrons. MHD simulations of DPFs supplement the experiments, in helping to choose experimental setups and uncover physics behind experimental measurements. We can model classic static-fill DPFs as well as DPFs with local mass injection – either by plasma gun or a gas puff on axis. Generators of varying maximum current and inductance are used to drive DPFs. The ongoing simulations and experiments involve local plasma injection and an axial gas puff, as well as conventional static fill. While we understand basic scaling related to MHD dynamics, there are several areas where the understanding is lacking. For example, most experiments use rods for the cathode (outer conductor), which allows gas and plasma to escape out of the space between anode and cathode. We perform 3D numerical simulations to understand this phenomenon and compare the results with conventional approach that assumes cylindrical symmetry and special boundary conditions.