The performance of a microwave ion source immersed in a multicusp static magnetic field

Abstract

Many applications requiring high beam currents and operation with chemically active gases impose lifetime and operational requirements on the discharge electrodes in conventional ion sources. Despite the development of specially designed hot filaments and hollow cathodes, the presence of these electrodes in the discharge zone still limits the practical application of ion and plasma sources. Thus, the development of an efficient, simple, electrodeless discharge would result in an important improvement in ion beam and plasma processing technology. Recently, an electrodeless microwave ion source and plasma source have been developed. An improvement of this ion source is discussed. This is the redesign to surround the discharge zone with many closely spaced rare earth magnets producing a confining and cyclotron resonant multicusp static magnetic field. The experimental performance of this ‘‘modified’’ ion source using argon gas is presented. Experimental measurements of extracted ion beam current versus accelerating voltage and discharge electron and ion densities, etc. are presented over a range of gas flow rates and operating pressures.