Measurement of the gas-flow reduction factor of the KATRIN DPS2-F differential pumping section

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• 作者：S. Lukić ; ; ¹ ; ^{strahinja.lukic@kit.edu} ; B. Bornschein ; L. Bornschein ; G. Drexlin ; A. Kosmider ; K. Schlö ; sser ; A. Windberger²
• 关键词：Gas flow ; Residual gas analyzer ; Vacuum measurement ; Free molecular flow ; Turbo-molecular pumping ; Monte Carlo simulation
• 刊名：Vacuum
• 出版年：2012
• 期刊代码：83_0042207x
• 类别：ph
• 出版时间：29 February, 2012
• 卷：86
• 期：8
• 页码：1126-1133
• 文件大小：503 K

摘要

The gas-flow reduction factor of the second forward Differential Pumping Section (DPS2-F) for the KATRIN experiment was determined using a dedicated vacuum-measurement setup and by detailed molecular-flow simulation of the DPS2-F beam tube and of the measurement apparatus. In the measurement, non-radioactive test gases deuterium, helium, neon, argon and krypton were used, the input gas flow was provided by a commercial mass-flow controller, and the output flow was measured using a residual gas analyzer, in order to distinguish it from the outgassing background. The measured reduction factor with the empty beam tube at room temperature for gases with mass 4 is 1.8(4)聽脳聽10⁴, which is in excellent agreement with the simulated value of 1.6聽脳聽10⁴. The simulated reduction factor for tritium, based on the interpolated value for the capture factor at the turbo-molecular pump inlet flange is 2.5聽脳聽10⁴. The difference with respect to the design value of 1聽脳聽10⁵ is due to the modifications in the beam tube geometry since the initial design, and can be partly recovered by reduction of the effective beam tube diameter.