Mechanisms of destruction of the partition foil of an electron gun, and methods of its protection, in the case of streamer breakdown of the discharge gap

The weakest spot of an electron-beam discharge laser is the electron-gun partition foil, and the main cause of its failure is the breakdown of the discharge gap, which destroys the foil by pressure-temperature increase or by radiation. An experimental setup for the investigation of partition-foil damage revealed that when the distance H of the foil from the grid reaches 4 cm, the pressure amplitude depends on the energy input unit length of the discharge gap, W/1, and also on 1/H. Increasing the distance between the electron gun and the antistreamer grid protects the foil against gasdynamic pressure and also against thermal destruction, since threshold energy of the latter increases with distance. At H = 5 cm, the foil was damaged by drops of molten metal from the antistreamer grid. Since the discharge-gap resistance drops sharply in streamer breakdown, connecting a ballast resistor to the discharge circuit effectively decreases energy released by the discharge arc.