High efficiency electron beam gun foil support

摘要

The reduction of the grazing angle of electrons in an electron gun with a cathode emitting a beam of electrons which pass through a thin foil into a chamber is accomplished by geometrically tailored electron gun foil supports. One embodiment of the invention replaces the conventional rectangular shaped ribs with a set of triangular shaped ribs which produce a grazing angle A given by the equation ##EQU1## where T=the base width of the ribPPS=space between ribs at the basePPH=height of the ribPPA=the angle the rib side makes with the incident electron which is perpendicular to the basePPA=also the angle the electron scatters at from the rib surface.PPAnother embodiment of the tailored foil supports entails the addition of triangular shaped caps to existing rectangular shaped ribs. The resultant reduction of the grazing angle of electrons improves the transmission efficiency of the electron gun and reduces the heat buildup on the supports and foil.