用于中子谱仪密闭型气体探测器的密闭腔研制

摘要

为避免高压气瓶带来的人身安全问题、不便携问题和污染工作气体排放问题,气体探测器已由流气型转化为密闭型。密闭型气体探测器可拓展气体探测器的应用范围,提高气体探测器竞争力,其缺点是腔内杂质气体会累积,影响探测器的性能(增益、分辨率和效率)和出现高压打火。本文采用螺旋弹簧密封实现密闭腔的动态高真空密封,采用铝和不锈钢复合板过渡实现铝和不锈钢焊接,采用高温烘烤、真空泵组抽高真空等方法实现密闭腔体净化,尤其是将铝表面微弧氧化技术用于真空腔体的净化。密闭腔微弧氧化后的杂质气体生成率相比未氧化的降低12.1%,杂质气体中氢气含量降低36%,水蒸气、一氧化碳和二氧化碳含量几乎下降1个数量级。腔体1 a 内产生的杂质气体含量为0.006%,2个月内产生的水分含量为0.0005%,可保证探测器2个月内不发生高压打火。研制出的密闭腔体满足中子谱仪密闭型气体探测器物理要求。%In order to ensure the personal safety and avoid the inconvenience of the high pressure gas cylinder and the emission of contaminated working gases,the gas detector has been changed from the gas-flow type into the enclosed type.The enclosed type gas detector can enlarge applications of the gas detector and improve competitiveness with the solid detector.The disadvantage of enclosed type gas detector is that the impure ga-ses will accumulate in the cavity,which will affect the detector performance (gain,reso-lution and efficiency)and cause high voltage spark.In this paper,the helicoflex sealing was used to realize the dynamic high vacuum seal,and the aluminum-stainless steel com-posite plate was used to realize the welding of aluminum and stainless steel.The high temperature baking and high vacuumizing by vacuum pump group were used to realize the cavity purifying.Especially,the micro-arc oxidation was used for the purification of the vacuum chamber.The gas generation rate of the impurities in the enclosed cavity is reduced by 12.1% after micro-arc oxidation.The hydrogen content is reduced by 36%. The contents of water,carbon monoxide and carbon dioxide almost all fall in an order of magnitude.The content of the impurity gas within 1 a will accumulate to 0.006%. Within 2 months the content of water will accumulate to 0.000 5%,which can ensure the detector works steadily for 2 months without a high voltage spark.The enclosed cavity developed is suitable for the enclosed type gas detector of neutron spectrometer.