The effects on ion beam optics of a spherical aberration at the plasma boundary

Surrey, E. ; Holmes, A. J. T.

[S.l.] : American Institute of Physics (AIP)
Published 1990
ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
Electrical Engineering, Measurement and Control Technology
Notes:
Experimental data show that the minimum divergence of a positive helium ion beam does not occur at the beam perveance predicted by linear ion optics. A model is presented that introduces a third-order term into the ion optics equations, in the manner of a spherical aberration to the plasma boundary. Values of the aberration coefficient C are calculated from the data and it is shown that Cāˆ(a/d)āˆ’1.9, where a/d is the aspect ratio of the accelerator. The contour of the plasma boundary is plotted and it is shown that the aberration leads to a flattening of the boundary at the extremes of the extraction aperture.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1141385