Arc discharge abnormality detecting system

摘要

The present invention provides an arc discharge abnormality detecting system which in generating source plasma by the arc discharge using a plurality of filaments as the cathode in an ion source, detects an arc discharge current flowing in each of the filaments and detects the abnormality in the arc discharge when the arc discharge currents are not balanced. Further, the present invention provides an arc discharge abnormality detecting system in which said ion source is an ion source used in a neutral beam injector and a logic circuit detects the abnormality in the arc discharge when unbalance in the arc discharge currents larger than a predetermined value exists between the filaments over a predetermined period of time continuously.