Time evolution of the x-ray emission from a micropinch in a vacuum spark discharge

The spectrum of the soft-X-ray emission of a Mg- micropinch plasma in a vacuum spark device has been recorded as a function of time, by employing a streak camera. The emission from the He-like ions occurs in two bursts - a very intense one of 200 ps duration and a second one of lower intensity but with a duration of 400 ps. The observations support the radiative-collapse model as explanation of the micropinching process and of the formation of the tiny hot plasmas of subnanosecond lifetimes.