Outgassing Analysis During Transport for 14m Long Arc-Cell Vacuum Chambers of the Taiwan Photon Source

An outgassing analysis during transportation for the large, 14-m-long, ultra-high-vacuum aluminum arc-cell chambers of the Taiwan Photon Source (TPS) was performed using residual gas analysis (RGA). Each cell was baked to 150 °C in the laboratory to achieve ultrahigh vacuum. Under pumping by primarily ion pumps (IP) and non-evaporable getter (NEG) pumps, the cells obtained pressures of 6.4×10 Pa on average, and the main residual gas was H2. Here, vacuum pressure measurements and residual gas analyses were performed in situ while a cell chamber was being transported. It was found that the vibration of the arc-cell vacuum chamber caused the pressure to rise abruptly; in this case, the main outgassing gas was CH4. Once the arc cell had been fully installed, the vacuum pressure gradually decreased to the original vacuum pressure because of the pumping effect of the ion gauges.