Pre-pulse suppression on Eros at AWE

The Eros facility at AWE was designed to simulate radiation effects using a large area diode driven by a low impedance Blumlein charged by a Marx generator. Recent interest at AWE to develop low impedance, high current pinched diodes, have lead to a need to use Eros for these experiments. Unfortunately Eros has no pre-pulse suppression beyond the balancing circuit that evens out the charging of the inner and outer lines of the Blumlein. This allows a pre-pulse of +/- 100 kV to reach the diode during the charging phase of the machine, too high a level for pinched diodes. To reduce the pre-pulse two options were considered, both of which are needed: 1) to install a pre-pulse gap into the stalk of the MITL; and 2) to install rail gap switches between the inner cylinder of the Blumlein and the insulator stack. The stalk pre-pulse gap was demonstrated to work on Eros improving self-magnetic pinch diode performance. The rail gaps were designed and then fitted during the year. Together these switches reduced the total pre-pulse on the diode by a factor of eight.