Phase space characterization of an internal ion source for cyclotrons

Orbit tracking codes are used to predict the behavior of the beam in a cyclotron before the cyclotron is constructed by tracking many orbits which collectively are intended to represent the beam. Cyclotrons with internal ion sources (such as the series of 250 MeV proton beam cancer therapy cyclotrons being manufactured by ACCEL Instruments GmbH of Bergisch-Gladbach Germany) present difficulty for these orbit tracking calculations in that there are several parameters which can be adjusted in the calculation that have a large effect on the phase space characteristics of the calculated beam (both the emittance of the beam and the shape of the beam in phase space). The primary goals of the research presented in this dissertation then are to experimentally measure the axial and radial emittance and luminosity of the beam produced by a cold cathode PIG (Penning Ion Gage) internal ion source under do extraction and to develop a "recipe" for initial conditions of calculated orbits starting from the ion source that match the experimentally measured beam.; The experimental results presented in this dissertation, to the best of our knowledge, represent the first published emittance and luminosity measurement of a cold cathode PIG internal ion source. By taking measurements in several different con figurations, it was determined that the shape and size of the source aperture has a large effect on the characteristics of the extracted beam. We were also able to observe that increasing the plasma arc current in the ion source produces higher current and luminosity in the extracted beam. The maximum luminosity measured using a chimney with a 5.0 mm (0.196&inches;) tall, 0.25 mm (0.010&inches;) wide slit, was 7.1 Acm2-sr . Two other chimneys with larger apertures were measured at lower arc currents being limited by the power handling capabilities of the Ion Source Test Stand.; The concepts of 'plasma boundary' and 'plasma temperature' are developed as a useful set of parameters for describing the initial conditions used in orbit tracking. We observe that an approximately flat plasma boundary provides the best match to the experimental beams emerging from the 'slit' style chimneys in our study, while a concave plasma boundary (curving toward the source axis) provides a better match for the beam that emerges from the 'hole' style chimney. In all cases, the plasma temperature that provides the best match for experimental beams is approximately 35,000 K (resulting in a central starting energy of 4.5 eV).; Using the methods presented in this dissertation, the orbit tracking code Z3CYCLONE is able to predict the beam produced by a cold cathode PIG ion source with adequate accuracy such that construction of actual cyclotrons can proceed with reasonably prudent confidence that the cyclotron will perform as predicted.