PURPOSE: To make any operator unnecessary by supplying power to a cooling mechanism subsequently after turning off a magnetron power source, and operating a timer simultaneously, being followed by stopping feeding power to the cooling mechanism after a timed interval which is set in a timer.

CONSTITUTION: When a magnetron power source is turned off, the contact 1 of an electromagnetic relay 7' is opened. In this state, since a current is fed to a coil which is connected to both the contact 1 of a timer 9' and the contact 4 of an electromagnetic relay 5', contacts 1W3 continue to be closed, and a pump 4' continues operating. Here, a time taken until an ion source becomes cool (about 30W60min) is set in a timer 9'. As a result, after the set time, the contact 1 of the timer 9' is opened, and the coil current of the relay 5' stops flowing. Consequently, the contacts 1W3 are opened, and the pump 4' stops its operation.