  The investigations of powerful discharge in high density hydrogen were
carried out on an installation with preliminary adiabatic compression. The
experiments were performed under the following conditions: stored energy of the
capacitive storage - 140-450 kJ, charging voltage - 8.0-14.0 kV, discharge
current amplitude- 200-600 kA, current rise rate - 10^9-10^10 A/s. The maximum
particle density nmax, achieved just before the discharge, was about 2.0x10^22
cm-3. It was observed one or several compression of the discharge channel. The
moments of contractions corresponds a increase of voltage on discharge gap and
feature on a curve of a current. Arc parameters were calculated on the basis of
the channel model. It was established that increase of the initial density of
particles at increase of a current rate of rise results in reduction of arc
diameter with increase of channel temperature.
