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UBC Theses and Dissertations

Development of an injection system for a compact H- cyclotron, the concomitant measurement of injected beam properties and the experimental characterization of the spiral inflector Dehnel, Morgan Patrick


This thesis addresses two major problems. One is of interest to commercial cyclotron manufacturers and the other is of interest to the accelerator physics community. The industrial problem was to produce a compact and modular ion source and injection system for the new TR13 H~ cyclotron, which is capable of transporting and injecting a high quality and well matched beam into the cyclotron. The accelerator physics problem was to advance the science of inflector ion optical design, analysis and troubleshooting from the realm of pure simulation to the realm of measurement and experimentation. The industrial problem was solved by designing candidate injection systems in parallel with the TR13 cyclotron design. These systems were fabricated and then experimentally optimized along with the ion source on a 1 MeV test cyclotron. This work resulted in a set of ion source and injection systems with well documented and understood properties. The recommended solution for the TR13 was a cost effective injection system composed of only two axially rotated quadrupole magnets. The accelerator physics problem is the lack of measured cyclotron inflector optical data and beam related properties in the immediate vicinity of a cyclotron inflector. This required the development of an experimental technique to overcome the numerous technical difficulties associated with making measurements near a device as inaccessible as a cyclotron inflector. A diverse assembly of equipment and procedures was required: a well understood injection system, a pinhole collimator for producing beamlets for ray-tracing, a specially configured center region to expose the inflector to view, a system of scintillators in close proximity to the inflector for producing visible beamspots, a TV camera and frame grabber to record images and a set of image analysis and data processing procedures. The results obtained using this technique were: (a) measured constraints on the coefficients of an inflector's transport matrix, (b) measurement of the beam's centering, size, shape and orientation in phase space at the entrance and exit of an inflector, (c) measurements of beam displacement as a function of field and energy perturbations at an inflector exit and (d) comparison of an inflector simulation code's capabilities against detailed measured data. Such properties of a beam have not heretofore been determined experimentally.

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