靶膜对中子管中子产额的影响分析

The Influence of Target Film Properties on the Yield of Neutron Tube

分析影响中子管中子产额的3个方面因素。靶膜材料选用单质金属钛或锆,要求纯度达到99.99%,纯度越高单位面积内吸附氚气越多,氘氚核反应的概率就越大。除单质金属靶膜材料外,还可以选用Ti-Mo合金替代单质金属靶材料;靶膜镀制工艺是保证靶膜质量的关键,要保证镀膜的本底真空度高于10-4 Pa,氩气的纯度达到99.99%,同时镀靶膜时给靶基加以400℃高温和200V直流偏压,以增加靶膜的附着力,最大限度地保护靶面不被氧化;靶膜厚度选择在1.0～1.5mg/cm2之间较为合适,既能保证氘氚核反应在有效深度范围内核反应概率达到最大,又不浪费氘氚气体。因此只有选择高纯度的靶膜材料、良好的靶膜镀制工艺和合理的靶膜厚度,中子管才能输出高的中子产额。

We analyzed three factors influencing the neutron yield of neutron tube which are the materials, thickness and film coating procedures. The target film is generally made of pure titanium or zirconium, the purity of them is required to reach 99.99%. The higher the purity, the greater adsorptive capacity to the tritium, and the higher probability of deuterium-tritium reaction. The Ti-Mo alloy is a good substitute for one of them as target film. The coating procedure is a key factor. During the coating process, the background vacuum should be higher than 10-4 Pa, the purity of argon should reach 99.99%. Meanwhile, the target base should be heated to 400 ℃ and supplied with 400 DC voltage so that the absorptive ability of the film enhances and the target surface can not be oxidized. The target film thickness should be 1.0-- 1.5 mg/cm2 so that it can not only provide the effect depth for deuterim-tritium reaction, but also economize the usage of deuterium and tritium gas. In practice, selecting the high purity material as target film, a good coating procedure and reasonable film thickness should be given more attention in order to obtain high neutron yield.