Negative ion beam injection apparatus with magnetic shield and electron removal means

摘要

A negative ion source is constructed to produce H- ions without using Cesium. A high percentage of secondary electrons that typically accompany the extracted H- are trapped and eliminated from the beam by permanent magnets in the initial stage of acceleration. Penetration of the magnetic field from the permanent magnets into the ion source is minimized. This reduces the destructive effect the magnetic field could have on negative ion production and extraction from the source. A beam expansion section in the extractor results in a strongly converged final beam.