High-Gradient Insulators

Vacuum insulator development for the dielectric wall accelerator

“…In fact, the conditioning procedures used by us may be too aggressive. This is suggested by the improved performance resulting from larger numbers of shots per voltage level ( n ), and by the surface damage observed in our samples, particularly the ablation and redeposition of metal which occurred in extreme cases 12 . While such large-scale movement of metal is certainly unhelpful, small-scale movement of metal may play a role in the conditioning effects we see by removing metal structures that are sources of field emission.…”

“…Testing is conducted using a dedicated high voltage test stand 12 . In this test stand, the samples are held between stainless steel electrodes in a vacuum chamber pumped to 2 x 10 -7 Torr.…”

“…Results for these insulators are summarized in Fig. 5 along with those for R173 12 , which was frequently removed from vacuum during testing and therefore did not receive the same conditioning benefits. Fig.…”

“…However, insulators in the DWA will be subjected to voltage reversals, preventing optimized use of angled insulators which have a preferred polarity, and the strong magnetic fields needed for magnetic flashover inhibition are not desirable as they would complicate beam transport. In support of DWA development, we are currently studying multilayer High-Gradient Insulators (HGIs) 12 . HGIs are vacuum insulating structures composed of alternating layers of metal and dielectric (Fig.…”