Contraction of superhigh pressure discharge channel at achievement of the Pease-Braginskii critical current

The research results of the discharge channel contraction depending on current amplitudes (0.5 – 1.5 MA), values of the initial pressure (5 – 30 MPa) and sort of gas (hydrogen, helium) are presented. The observed reduction of the brightness temperature of the channel with increasing of input energy is conditioned by heating of surrounding gas. The contraction of the channel, registered near current maximum, is associated with achievement of the Pease-Braginskii critical current. As it was shown earlier, at megaampere current amplitudes the discharge burns in metal vapor of eroded electrodes. The theoretical value of the Pease-Braginskii critical current in this case is ∼100 kA. Registered critical current increased up to ∼1 MA is associated with absorption of the channel radiation in consequence of high density of surrounding gas.