Result of curretn flow with a linear density of 1–3 MA/CM and duration of 100 NS across stainless steel electrodes

Summary form only given. When the current has a linear density of 1-3 MA/cm and duration of 100 ns the diffusion of the magnetic field deep into the electrode is complicated by heating the metal and the formation of the plasma on the surface. A series of experiments on the transmission of current with a rise time of 100 ns and amplitude of about 3 MA across stainless steel electrodes was conducted on the Angara-5-1 facility. The electrodes were hollow tubes with a wall thickness of 1 mm. The diameters of the tubes were 3 mm and 12 mm.Rate of expansion of the outer boundary of the electrode by passing through it a current pulse was measured by laser shadow picture. The laser pulse duration was of 0.1 ns. Laser shadow pictures were made in time moment, when current arrived at maximum. It is found that the average rate of expansion of the plasma on the outer surface of the tube at a time close to the peak of the discharge current with a linear density of 2.5 MA/cm, is about 4.6 km/s. The electric field arising on an internal surface of a tube, was measured by means of a resistive divider. It was found that at mid-height profile of the electric field on the inner surface of the tube behind the current profile of 200 ns. However, the maximum electric field intensity on the inner surface of the tube is behind the current profile for 300 ns. This is apparently due to nonlinear processes of heating, melting, evaporation, ionization and plasma formation. Comparison of the registered electric field temporal profile of the inner surface of the tube with the results of its calculation allows for verification of the computational model.