Ron headed up Group 14 at litton. It's a rough envirnoment. Things break too often in that area. He'd had it with crowbar problems so he did some hipot research. He found that a .1 Microfarad capacitor did no damage to heavy-duty Renolds Wrap, when arced through a decent resistor. He went up to 50KV, down to 10 Ohms; and he didn't blow holes in the foil. We'd had trouble, sometimes blowing holes in foil even with ignitron crowbar protection, using the same output cap and resistor values--down at 15KV!
Ron's message was clear: follow-on current was our real enemy. Gating the pass-tube off is sufficient protection, when done right. He ordered six large multi-output 30KV tube testers without crowbars. It was a struggle but we proved him right, eventually extending the design to 60KV. |