Research Of The Bremsstrahlung Converter For High-power Irradiation Linacs

X-ray produced by high energy electron beam targeting is a widely-used kind of irradiation sources in irradiation processing field. Irradiation by X-ray has good forward intensity distribution and penetration ablity. Meanwhile, because the conversion efficiency is quite low, the vast quantity of heat deposited in the target, especially when the power is high, requires particular design of the converter.This article starts from the Bremsstrahlung theories, based on the derivation, Monte-Carlo method and related codes are used in research about the X-ray conventer of linacs, including three parts:The principle, application, research and developing status of irradiation linacs home and abroad are given. The related fundamental theories used in the article work are introduced, including the theoretical analysis of X-ray converter and angle-distribution of Bremsstrahlung. After that, methods and software, such as Monte Carlo Method, MCNP and ANSYS, used in this article are briefly introduced.Next, the whole beam route of the linac is investigated and designed. The quadrupole lenses are manufactured and arranged to the right position on the linac, according to the designed mechanical and electrical parameters.The X-ray converter of high-power irradiation linacs is discussed as the main part of this article. Because the beam power of the irradiation linac is quite high, the deposited energy in the convertor will begreat, which brings forward high demands on the converter design. Based on the simulation of MCNP, the target materials and thicknesses are selected, and the multi-layer structures of two design schemes are optimized. Two specific converters are developed with 1.7mm tantalum and 1.5mm tungsten (has been produced) as main targets. The stainless steel board with the 3 channels for cooling water is used as the base of the converter and filter for low energy part of bremsstrahlung spectrum. The study of the cooling effect and thermal distribution shows that the design can meet the actual requirements for long-time irradiation. The dose distribution results are stimulated for the research on the X-ray planar and spatial uniformity.