Plasma evolution from rod-pinch diodes

Summary form only given, as follows. The rod-pinch diode concentrates an intense electron beam onto the tip of a tungsten rod anode, producing an intense x-ray source with sub-mm spot size? Plasmas evolving from the electrodes can influence electron trajectories, affecting the diode impedance and the x-ray source distribution. Plasma evolution from 1- and 0.5-mm-diam rod-pinches operated at 1.5 MV, 40 kA, and 50 ns on Gamble I1 is investigated using Schlieren photography, shearing interferometry, and high-sensitivity, twocolor interferometry3. The measurements show plasma expansion from the last 5 mm of the rod, with low-density plasma expanding at 10 c d p and high-density plasma expanding at 1-2 c d p. Results are compared with MHD and hybrid simulations of expanding plasma resulting from electron beam deposition. Implications for rod-pinch operation will be discussed.