中文摘要：

为消除波荡器产生的高次谐波对国家同步辐射实验室新建的U14C光束线的影响，同时维持光束线中其他各子系统能在超高真空环境下工作，使用了三级差分抽气滤波系统．测试结果显示，在PAr〈1．333kPa时，光束线真空度维持在〈1．09×10^-6 Pa；往气室内通1．333kPa Ar时，可有效抑制高次谐波的通过，效率达99．97％以上，光束线真空度维持在2．53×10^-7 Pa，有效地降低了气体外泄至光束线的干扰．

英文摘要：

A gas filter system was designed for a newly built U14C beamline at National Synchrotron Radiation Laboratory to eliminate high order harmonic radiation and maintain other systems of the beamline in ultrahigh vacuum environment. The differential pumping system contains a gas cell and three differential pumping regions. Testing results indicate that the beamline pressure is still kept at lower than 1.09×10^-6 Pa when the pressure of Ar in the gas cell is lower than 1. 333 kPa, that the vacuum of the beamline is around 2.53×10^-7 Pa with 1. 333 kPa Ar in the gas filter, and radiation could be suppressed better than 99.97%.