TUP009 　加速器土木・放射線防護/真空　 8月10日 会議室P 12:50 - 14:50

Pd、Pd/TiZrVコーティングした銅チューブの昇温脱離と排気性能の評価

Thermal desorption and pumping performance studies for Pd or Pd/TiZrV coated copper tubes

○金 秀光，谷本 育律，内山 隆司，本田 融（高エネルギー加速器研究機構）

○Xiuguang Jin, Yasunori Tanimoto, Takashi Uchiyama, Tohru Honda (High Energy Accelerator Research Organization)

In non-evaporable getter (NEG) coating, the coated film (TiZrV) thicknesses are limited in micrometer range and sorbed gases diffuse into the films (except H2) during activation, so the repeated air venting causes oxygen enrichment at near surface with resultant degradation of the pumping performance. To solve this problem, Pd overcoated getter films have been proposed and H2 and CO pumping performance have been studied. However, the thermal desorption and the Pd thickness effect on the pumping performance have not been reported. Herein, Pd, or Pd/TiZrV coated copper tubes were prepared using a magnetron sputtering. In thermal desorption after CO dose, the Pd/TiZrV film releases much more CO and CO2 than the TiZrV film, indicating Pd surfaces have lower concentration of the carbon after activation. At the H2 pressure of 5x10-6 Pa, the Pd and Pd/TiZrV films show higher sticking probabilities than the TiZrV film due to the superior H2 dissociation rate of Pd. By contrast, at the H2 pressure below 6x10-7 Pa, Pd film exhibits negligible H2 pumping, and thicker Pd overcoated TiZrV film shows lower H2 pumping. Pd has higher hydrogen dissociation pressure and limits H2 pumping.