Extinguishing of the Electric Arc Compressed by Shock Waves

Abstract

In the front of a shock wave travelling in plasma of the electric arc, the conductivity is increased with temperature and ionization degree. However, the increase of conductivity cannot compensate compression because of limiting initial arc size. As a result, the resistivity of the gap with the electric arc in which the shock wave is spread is increased. It is explained by the fact that temperature and, consequently, conductivity increase very slowly when compared with the compression cross-section of the arc at moderate velocities of shock waves. The most considerable effect of the resistance increase must be observed at a following arc compression by the reflected shock waves.

The size of the arc compressed by the shock wave is decreased for order or more when compared with the initial one. In this case the determining factor which has an influence on thermodynamic state of plasma is the interaction of plasma with limiting walls and with the piston. The energy release through the walls and to the piston may considerably increase the arc resistance.

Current effect on compressed arc can have a strong influence on process character in plasma. Apparently, this effect will be defined by the current values in arc and by the character of voltage increase in the gap which is determined by parameters of electric circuit.

In this paper the experimental results of the check of mentioned above considerations are presented.