A POSITIVE ION SOURCE

Abstract

Positive ions are formed in a low pressure electrodeless discharge which is excited by the radio-frequency field of a coil coupled to a 15 Mc. per sec. oscillator. The ions are extracted from the discharge through a pumping canal (2 mm. in diameter × 12 mm. in length) by a simple arrangement of electrodes. After further focusing and acceleration to 50 kv., the beam current at the target is 500 μa. and the focal spot is 6 mm. in diameter. Magnetic analysis has shown that the beam consists of 50% protons when using hydrogen in the discharge and 60% deuterons when using deuterium. Gas is supplied to the source at the rate of 15 cc. per hr.