Characteristics of helium ion beams from multicusp source and study of beam transport

Abstract

A test stand with a multicusp type He/sup +/ ion source and an electrostatic transport system was built for the study of beam characteristics at relatively low energy, E<10 keV, and beam transport in a space-charge dominated region with /spl beta/(=v/c)<0.0025. The measured normalized beam emittance (90%) of the He/sup +/ beam extracted from a compact multicusp source is about 0.08 /spl pi/ mm-mrad for the emission current density of about 5-15 mA/cm/sup 2/ at 6-9 kV. An electrostatic quadrupole transport system (ESQ) is designed for this beam. Preliminary experimental results show that the ESQ has a potential to transport a beam without any significant emittance growth over a length of about 50 cm.