Novel matching lens and spherical ionizer for a cesium sputter ion source
Date
2009-06-04T06:13:44Z
Authors
Weisser, David
Lobanov, Nikolai
Hausladen, P
Fifield, L Keith
Wallace, Howard
Tims, Stephen
Apushkinsky, E
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Indian National Science Academy
Abstract
The beam optics of a multi-sample sputter ion source, based on the NECMCSNICS, has
been modified to accommodate cathode voltages higher than 5 kV and dispenses with the nominal
extractor. The cathode voltage in Cs sputter sources plays the role of the classical extractor accomplishing
the acceleration of beam particles from eV to keV energy, minimizing space charge effects
and interactions between the beam and residual gas. The higher the cathode voltage, the smaller are
these contributions to the emittance growth. The higher cathode voltage also raises the Child’s law
limit on the Cs current resulting in substantially increased output. The incidental focusing role of the
extractor is reallocated to a deceleration Einzel lens and the velocity change needed to match to the
pre-acceleration tube goes to a new electrode at the tube entrance. All electrodes are large enough to
ensure that the beam fills less than 30% of the aperture to minimize aberrations. The improvements
are applicable to sputter sources generally.
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Keywords
beam optics, ion source, space charge
Citation
Pramana 59.6 (2002): 997-1006
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Pramana
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Journal article
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