Current initiation in low-density foam z-pinch plasmas

摘要

Low density agar and aerogel foams were tested as z-pinch loads on the SATURN accelerator. In these first experiments, we studied the initial plasma conditions by measuring the visible emission at early times with a framing camera and 1-D imaging. At later time, near the stagnation when the plasma is hotter, x-ray imaging and spectral diagnostics were used to characterize the plasma. Filamentation and arcing at the current contacts was observed. None of the implosions were uniform along the z-axis. The prime causes of these problems are believed to be the electrode contacts and the current return configuration and these are solvable. Periodic phenomena consistent with the formation of instabilities were observed on one shot, not on others, implying that there may be a way of controlling instabilities in the pinch. Many of the issues involving current initiation may be solvable. Solutions are discussed.