Gabor lens focusing of a negative ion beam

A Gabor lens constructed at Fermilab has been used to focus a 30 keV proton beam with good optical quality. In the present work, the author discusses the action of a Gabor lens on a beam of negative ions. A Gabor lens has been considered for matching an H/sup -/ beam into a radio-frequency quadrupole (RFQ) in the redesign of the low energy section of the Fermilab linac. It is shown that it is not feasible to focus a negative ion beam with a Gabor lens due to the large magnetic fields necessary to contain the nonneutral ion plasma.<
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