摘要
以重离子束医用装置中真空膜窗为测试对象,设计了一套实验装置,测定了空气在膜窗中的渗透率,比较了单双层窗膜对空气渗透系数,并分析其原因。结果表明:单双层膜窗对空气中各种气体渗透率中水蒸汽最高,氩气和氦气最小,氢气、氧气、氮气以及碳氢化合物各不相同;中间腔压强为1.5 Pa时,双层膜窗对空气渗透系数为单层膜窗的一半3.22×10-10cm2/s。说明双层膜窗结构对空气阻隔效果好。减小膜变形以及降低膜两侧压差的结构有利于提高膜窗对气体的阻隔性能。
Air permeation through the single-layer and double-layer vacuum membrane window of the heavy-ion cancer therapy facility at room temperature was experimentally studied with a lab-built setup. The penneability coefficients of different gases in air were determined, respectively. The results show that the penneability of different gases through the single-and double-layer membrane window can be aligned in a descending order： H20, N2, H2, O2, CxHy, CO2, Ar, and He. The permeability coefficient of air through the double-layer membrane window was found to be 3 . 22× 10^ - 10 cm2/ s at a pressure of 1.5 Pa between the two layers, which was only half of that through the single-layer membrane. Possible mechanisms responsible for the reduction were tentatively discussed. Wesuggest that the double-layer membrane window have better barrier property because it considerably reduces the pressure difference and pressure - induced membrane deformation.
出处
《真空科学与技术学报》
EI
CAS
CSCD
北大核心
2014年第2期126-129,共4页
Chinese Journal of Vacuum Science and Technology
关键词
渗透系数
真空膜窗
重离子医用装置
阻隔性能
Penneability coefficient , Vacuum membrane window, Heavy- ion medical machine, Barrier properties
