Initial Operating Experience with the TRIUMF 300 keV H- Injection System

Abstract

The present TRIUMF injection system consists of a 12 keV Ehlers type unpolarized H- ion source located in a 288 keV accelerator terminal, and connected to the cyclotron by a 35 m long injection line which contains two 90 deg electrostatic bends, three periodic quadrupole sections, and elements to pulse, bunch and chop the beam. The stray magnetic field from the cyclotron has been compensated in the source and along the beam line with passive shielding and ferrite permanent dipoles. The beam enters the cyclotron axially and is bent into the median plane by means of a spiral inflector. This system is now being commissioned and currents of 50 μA dc and 250 μA peak in a pulsed mode have been obtained with 90% transmission. Currents of 500 μA dc and a bunched beam of 1.5 mA peak have been obtained previously in the prototype injection system, and similar performance can be expected with the present system. A polarized H- source is under construction.