We have tested endurance of Kapton foil for beam irradiation, which is used as an exit window of in-air PIXE system. kaptoon foil is strong enough to withstand the pressure differential, thin enough to transmit the proton beam with minimal energy loss and does not contain heavier elements. However, little is known about the relation between its ifetime unitl breakdown and beam parameters such as beam current, beam diameter and energy lass. Endurance test were made by an in-air PIXE system at Tohoku university. Irradiation was performed by proton beam with 2 or 3 MeV until the foil was broken for various beam parameters. The total charge until breakdown of the Kapton foil was anayzed in consideratioin of beam current, diameter and energy loss. Total charge until breakdown decrease with increase in the beam current density in case of the beam current density higher than 100 nA/mm~2. The lifetimne of the Kapton foil can be estimated longer than 2 days for the beamn current density of 10 na/mm~2 (7nA in 1 mm beam diameter). It is sufficient for the in-air PIXE analysis.
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机译：我们已经测试了用于光束照射的Kapton箔的耐久性，该箔被用作空中PIXE系统的出射窗。 kaptoon箔足够坚固，可以承受压差，足够薄，可以以最小的能量损失传输质子束，并且不包含较重的元素。但是，关于其短暂的单位击穿与光束参数（例如光束电流，光束直径和能量损耗）之间的关系知之甚少。耐久力测试是由东北大学的机载PIXE系统进行的。用具有2或3 MeV的质子束进行辐照，直到箔因各种束参数而破裂。考虑到电子束电流，直径和能量损失，分析了直到Kapton箔破裂为止的总电荷。在束电流密度高于100 nA / mm〜2的情况下，直至击穿的总电荷随着束电流密度的增加而降低。对于束流电流密度为10 na / mm〜2（1 mm束直径为7nA），可以估计Kapton箔的寿命超过2天。足够进行空中PIXE分析。
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