Electron beam device with single crystal window and expansion-matched

Abstract

A vacuum tube electron beam device having a thin, single crystal, electron permeable, gas impermeable membrane for electron transmission and methods for making such a device. Single crystal membranes can have small thickness due to high strength, are highly transmissive to free electrons due to that small thickness. The ordered crystalline structure of such membranes provides minimal obstructions to electron beams, and yet is highly impermeable to penetration by gas and liquid molecules. Single crystals are anisotropically etched to precise membrane dimensions, and can also be etched to provide microchannel structures for flowing cooling fluid across the membrane during use. A doped silicon anode can provide support for the membrane with matching thermal expansion characteristics, and a crystalline anode can be integral with the membrane. A double membrane embodiment confines the cooling fluid so that it passes close to both membranes. A double membrane structure can also have a pressure between the membranes that is between the pressure within the vacuum tube and ambient pressure outside the vacuum tube, allowing the membranes to be thinner. The membrane can also be compressed for increased strength. A number of cooling methods are used to maintain the integrity of the membrane.