IBIS: A hollow-cathode multipole boundary ion source

Abstract

The plasma production and containment system for a high‐power continuously operating magnetic multipole ion source has been designed and constructed. Preliminary tests on this system prior to high voltage extraction of large beams indicate advantageous performance for neutral‐beam injection applications. The source has produced 80 A to the extractor region at 0.33 A/cm2 with a discharge of 330 A at 80 V. Density uniformity is better than 1% over a 16‐cm diameter, dropping to −4% at 18 cm, with plasma noise of less than 3%. Gas utilizaion efficiency and atomic (H+) species output are anticipated to be high due to a source length of 40 cm. This quiet efficient performance is attributed to the use of a hollow‐tube LaB6cathode and an improved magnetic multipole confinement system.