Progress in the Development of a 4 Mv Positive Ion Accelerator for High Beam Currents

The symmetrical 4 MV cascade generator is a dc accelerator power supply which provides both high voltage and high current capability at low ripple voltage.1 The problems usually encountered in the accelerating tube like total voltage effect, electron loading, and X-ray generation were solved by utilizing built-in permanent magnets for the deflection of the backstreaming electrons. This design reduces electron loading and brings the X-ray intensity down to a harmless level. With a R. F. ion source of conventional design, proton currents up to 1 mA at 4 MeV were actually obtained on the target. A further increase in the beam current is expected by the use of a duoplasmatron ion source.