Spatial and temperature structure of vacuum spark plasmas

The spatial and temperature structures of the X-ray emitting components of low-inductance vacuum spark plasmas are investigated. The plasmas produced by low-inductance vacuum sparks show striking resemblances to solar flare plasmas. High-resolution photographs show that the spark plasmas are composed of hot (approx.30times10$sup 6$ K) compact sources (<20 $mu$) and cooler (approx.10times10$sup 6$ K) larger sources (approx.100 $mu$). Both types of sources may be produced by the same plasma at different times. The differences between the solar flare iron-line spectrum near 1.9 A and the spark iron-line spectrum are discussed and interpreted. (AIP)