Structure and dynamics of the plasma armature of railgun macroparticle accelerators

Abstract

Results of the optical diagnostics of the plasma armature in railgun macroparticle accelerators are summarized. Determining the structure of the plasma armature and measuring its brightness and temperature at an initial stage of high-current discharge are the focus of attention. Experiments show that the plasma induced by the electric explosion of a copper foil undergoes complex variations that include plasma stratification. The plasma structure continuously changes, being of a complicated, irregular character. The lifetime of an individual stratum changes within 1 to 10 mu s. In experiments on solid-body acceleration, the arc burns for a long time at the foil site, where a strong electrode erosion takes place. As the body passes through the railgun channel, the plasma armature continuously increases its length so that it gradually occupies the entire accelerator channel. the current is observed to redistribute itself from the front towards the end face of the plasma armature. The maximum brightness temperature measured in the experiments is 26000+or-2600 K. As is shown by the experiments, it is arguable that a magnetic-compressed discharge may be realized in a railgun solid-body accelerator with a plasma armature. >