Cathod discharge performances of indirect heated ion sources

Characteristics of indirect heated cathode of lanthanum hexaboride under heating up to 1900 K are investigated. Temperature distribution over working surface of the cathode is presented. Determination of discharge current was conducted in a pulsed regime in the 6x10-4-4x10-1 Pa hydrogen pressure range. Low rate of discharge current rise is noted under cathode heating up to 1500 K, that is conditioned by presence of defect layer, which is evaporated at higher temperature. Rate of cathode heating should not exceed 15-20 deg/s. The cathode is distorted at heating rate above 30 deg/s. Discharge current makes up 490 A, discharge current density constitutes 14 A/cm2 at 1700 K cathode temperature and 300 V anode voltage