本文主要介紹台灣光子源(Taiwan Photon Source, TPS)之真空系統設計及原形建造,台灣光子源為一座能量30億電子伏特的同步加速器光源。其電子儲存環周長共518.4公尺,其鋁合金真空系統設計必須考慮極低表面釋氣率、低氣導阻抗的結構,並提供無油的抽氣系統及少油的製造流程。一段原形真空系統(全長14公尺)已經建立,其所有尺寸、真空元件皆以實際尺寸製作及組裝,目的在於驗證真空設計及找出製造、安裝過程的問題,作為後續建造之參考。一段原型真空系統有兩個彎段真空腔,各長4公尺,是使用CNC加工方式製造完成,使用酒精作為冷卻液,以防止任何污染源附著於鋁合金表面,並用臭氧水清洗之方式,減少從真空腔表面所釋放之PSD,然後利用自動銲接系統來完成真空腔兩側之銲道。本文除了介紹超高真空系統之設計概念外,並著重於製造流程及最終氣壓之研究。
The design and a prototype of the vacuum system of a low-emittance 3-GeV synchrotron light source, the Taiwan Photon Source (TPS, with circumference 518.4 m), are described. The TPS vacuum system has low-outgassing aluminum beam ducts, a low-impedance structure, an oil-less pumping system and oil-less fabrication. Little dust, a stable mechanical structure and highly reliable components are achieved for this vacuum system. A prototype (length 14 m) of the TPS vacuum system was fabricated. Two bending-magnet chambers, 4 m long, were made with computer-numerical control (CNC) machining and lubricated with ethanol to protect the aluminum surface from oil contamination. Cleaning with ozonized water was applied to decrease the rate of photo-stimulated desorption (PSD) from the chamber surfaces. Then an automatic welding system is used to implement the side welding seams of bending chambers. The design considerations, the critical factors in fabrication and the test results of the vacuum system prototype are presented.