Abstract: Electrostatic x-ray imaging apparatus of the type having a gas-filled chamber bounded by a photocathode and a charge-receiving sheet anode has a control mesh positioned in the gas-filled gap and maintained at a positive voltage with respect to the cathode to facilitate high avalanche amplification and has a voltage between the mesh member and the anode chosen in the plateau region of the x-ray photocurrent versus voltage curve, to achieve a nearly constant efficiency of charge collection at the anode, independent of accumulation of charge thereat.

Abstract: In high-current vacuum switch devices wherein the arc must transfer from the contacts to auxiliary electrodes, excessive contact erosion can be avoided by making this transfer occur as quickly as possible. Rapid transfer is facilitated by fabricating the contacts of refractory metal and the auxiliary electrodes of a material that is easily vaporized, consistent with chopping and recovery requirements, such as copper or iron.