Important issues from x-ray studies of high-current pulse discharges of the plasma-focus type

Abstract

The paper reports on recent measurements of the X-ray emission from a large plasma-focus PF-1000U facility [1] and compares them with results from the old Poseidon device [2]. The most important results of time-integrated measurements, which were performed by means of an X-ray pinhole camera, are presented and analyzed. Attention is paid to studies of a fine structure of the collapsing current sheath and dense pinch column. Observations of plasma filaments and so-called “hot spots” are discussed. The first observation of plasma filaments inside the PF pinch column [3] was later confirmed by some small-scale PF experiments, but in the large PF-1000U facility plasma filaments have for the first time been recorded recently. Other new results are time-integrated X-ray images of PF-1000U discharges with the gas puffing, which in some cases show very distinct “hot spots” formed outside the dense pinch core. They are explained by local neckings of spiral current filaments which surround the central pinch column.