|
Experimental Advanced Superconducting Tokamak (EAST) is the first whole superconducting tokamak commissioned in the world. Like ITER, it is designed to have the capacity of operating in limiter, single or double null divertor configurations. Also similar to ITER, during the plasma experimental operation, all the toroidal and poloidal field coils are in the superconducting state. In March 2006, the cryogenic system was commissioned. After minor maintenance involving leak recovery, the first high temperature plasma (limiter discharge) was obtained in September 2006. In January 2007, first divertor plasma discharge was realized after the commissioning of a Plasma Control System. Vacuum system is one of the most important sub-systems of EAST device. Leak detecting is essential for the success of the engineering commissioning, especially for such a whole superconducting device. Wall conditioning also plays a very important role for the plasma operation. EAST routinely use Ion Cyclotron Resonance Frequency wave for wall conditioning, which could work with a high toroidal magnetic field. This technique is a candidate for ITER wall conditioning. Besides the usual application on discharge cleaning, it is also used for boronization, a key wall conditioning process for suppressing impurities on EAST. This paper describes the vacuum operation of this new device. The first part includes the designing and construction of the vacuum system. Secondly, the leak detecting during the construction and operations are emphasized. Thirdly, vacuum measurement and calibration are introduced. Fourthly the wall conditioning, including baking, glow discharge cleaning, ion cyclotron resonance cleaning and boronization are discussed. Other related sub-system e.g. vacuum control is also described in this paper. |