GB1241371A - Apparatus for electron beam irradiation - Google Patents

Abstract

1,241,371. Electron beam irradiation apparatus. T.I. (GROUP SERVICES) Ltd. 14 April, 1970 [16 April, 1969], No. 19316/69. Heading H1D. The window of an electron beam irradiation apparatus comprises an electron permeable membrane of titanium or aluminium adapted to withstand atmospheric pressure, and a second membrane spaced from the first and permeable to electrons and to gas. The second membrane may be a mesh of aluminium, titanium, nickel, stainless steel, or non-metallic material and a cooling gas may be circulated between the membranes without disturbing the irradiated material, which may be paint. Preferably, the gas flow is achieved by providing equal and opposite and negative pressures along two edges of the membrane, so that the mean pressure on one side is the same as that on the opposite side, e.g. atmospheric pressure, and the gas flow should be in the same direction as that of the work. The second membrane should absorb less than 50% and preferably less than 30% of the incident electrons and should have apertures less than 5 mm. across. The membrane may include wires that absorb substantially all incident electrons, in which case the area of the membrane should be not less than 80% open. Alternatively, a better distribution of the electron dose in the work may be achieved if the solid parts of the membrane are so thin that the total mass thickness of the solid parts, together with the cooling gas and the first membrane is less than half the range of the electrons used (which is proportional to the mass traversed). In this case the area of the solid parts should be 40-60%.