Design of high power RF window for drift tube linac

In order to develop a RF coupler for the drift tube linac of China Spallation Neutron Source, by improving the conventional RF window structure, we designed a new RF window of the RF coupler. High frequency characteristics of this window were optimized in CST. The calculations of the temperature rising and the thermal stress caused by the high power were performed to avoid the ceramic broken. The fundamental mechanism of the window under vacuum was investigated. Finally a preliminary discussion on the ARC phenomenon was made too. The results show that the in-put power 2 MW of the cavity is less than the critical value 2.355 MW, and the probability of strike arc is very small.