Design and Performance of a Radio-Frequency Ion Source

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Abstract
Tests were made on a 27-megacycle, inductively coupled, radio-frequency ion source standardized in design for use at the Los Alamos Scientific Laboratory. Total deuteron beam current and probe current characteristics were found, in tests made before installation, as a function of gas pressure of the discharge, rf power input, probe voltage, and extraction system geometry to determine the best values of these variables to use. These characteristics showed a maximum total beam current of 600 μa to be obtained with roughly 200 watts of rf power input. Tests made after installation in an accelerator gave 92 percent monatomic deuteron beams of up to 80 percent the strength found under similar conditions in the tests made before installation. A platinum-coated envelope gave a triatomic beam of about one-eighth the strength of the monatomic beam obtained with an uncoated envelope. The source has been used at 150-psi external pressure in a Van de Graaff tank.