High energy-density plasma dynamics in plasma-filled rod-pinch diodes

High energy-density plasma (HEDP) is created using a plasma-filled rod pinch diode (PFRP)¹ on the Gamble II generator (2 MV, 0.7 MA, 60 ns with a matched 3-Ohm load). The PFRP consists of a 1-mm diameter tungsten rod that extends 25 mm through a hole in a grounded cathode plate. Plasma is injected from six cable guns 1 microsecond prior to firing the generator. The plasma acts like a short circuit while the current increases to 600 kA, then the PFRP impedance increases and a ~2 MeV, 500 kA electron beam deposits energy at the end of the rod. When the rod is tapered to a sharp point, the energy density is estimated to reach 2.4 MJ/cm³ in about 10 ns before rapid expansion decreases the energy density.¹ The work reported here is aimed at measuring the plasma temperature and density, and inferring the pressure from the early-time dynamics of the expanding plasma.