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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。
Taking the vacuum membrane window of heavy ion beam medical device as test object, a set of experimental device was designed. The permeability of air in membrane window was measured and the air permeability coefficient of single and double window membrane was compared and the reason was analyzed. The results show that the single-double membrane window has the highest water vapor, the lowest argon and helium, and the different hydrogen, oxygen, nitrogen and hydrocarbon in the gas permeability. When the cavity pressure is 1.5 Pa, The permeability coefficient of the membrane window to the air is 3.22 × 10 -10 cm 2 / s, which is half of the single-layer membrane window. Description double membrane window structure of the air barrier effect. The structure of reducing the membrane deformation and reducing the pressure difference on both sides of the membrane is favorable for improving the barrier performance of the membrane window to the gas.