A protection circuit for power diodes under heavy ion bombardment is presen
ted, which allows to acquire failure waveforms without destroying the devic
e under test. An ultra-fast, high voltage switch based on eight vacuum tube
s is employed to short the device within less than 100ns from the potential
ly destructive impact. Some waveforms have been safely acquired in conditio
ns where the device could have been destroyed in absence of protection. (C)
2001 Elsevier Science Ltd. All rights reserved.