Orson Sutherland, a) John Keller, Michael Irzyk, and Rod Boswell

Plasma Research Laboratory, RSPhysSE,
Australian National University, 0200 Canberra, Australia
Received 18 February 2003; accepted 16 March 2004;
published online 21 June 2004

Computer simulation codes for the extraction of ion beams have been used for over three decades. Here we describe medium current extraction 1 mA from a high density plasma source (1012 cm3 ) with a three electrode extraction system and compare the extracted current and the angular divergence with the results of two computer simulation programs. The first is called PBgun and is a commercially available ray tracing code; the second, called simulation d’extraction de faisceaux d’ions SEFI uses a particle-in-cell code to simulate the plasma and ion beam. It is the purpose of this article to ascertain whether these codes can adequately model the plasma/beam interface and hence successfully predict the extracted current and beam form across a broad range of extraction parameters. We found that SEFI could accurately predict the function of extracted current versus extraction voltage and that PBgun gave accurate simulations when the current or current density could be specified near the meniscus. Also for a thin plasma aperture and a fixed current at the meniscus, PBgun gave roughly 60% of the functional dependence of the extracted current on the extraction voltage and the other 40% on variations in the plasma pre-sheath. Both codes had some error from beam crossing near the axis which changed the amount of meniscus curvature predicted.

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 © 2004 American Institute of Physics. DOI: 10.1063/1.1753669 REVIEW OF SCIENTIFIC INSTRUMENTS VOLUME 75, NUMBER 7 JULY 2004

Also see the following US Patents

US 6,838,677   Extraction and deceleration of low energy beam with low beam divergence
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US  7,670,455   Magnetically enhanced, inductively coupled plasma source for a focused ion beam system
US  5,686,796  Ion implantation helicon plasma source with magnetic dipoles

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