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DEVELOPMENT OF A FOUR CAVITY SECOND-HARMONIC GYROKLYSTRON AS DRIVER FOR A LINEAR ACCELERATOR

dc.contributor.advisorAntonsen, Thomas Men_US
dc.contributor.authorGouveia, Emmanuel Steveen_US
dc.date.accessioned2004-07-16T05:20:10Z
dc.date.available2004-07-16T05:20:10Z
dc.date.issued2004-06-16en_US
dc.identifier.urihttp://hdl.handle.net/1903/1692
dc.description.abstractGyroklystrons are microwave amplifiers that combine the multi-cavity configuration of a klystron with the energy extraction mechanism of the cyclotron maser instability. These devices have been studied at the University of Maryland for several years. This work is focused on the development of a 17.14 GHz four-cavity frequency-doubling gyroklystron circuit. This device was designed specifically to drive a high gradient linear accelerator recently developed by the Haimson Corporation. The gyroklystron was designed using the code MAGYKL, yielding a predicted output power of 87 MW for an input drive power of 250 W, with a velocity pitch ratio (alpha) of 1.4. The tube was later fabricated, and underwent a series of experimental tests to evaluate its performance. The highest peak power observed was 18.5 ± 1.7 MW, corresponding to an efficiency of 7.0 % and a gain of 24.0 dB. This result fell short of the theoretical design, yet it was consistent with the low value of the velocity pitch ratio (alpha=0.85) realized in the experiments. This limitation on alpha was linked to the onset of instabilities in the input cavity. The ultimate cause of these instabilities was the thermal non-uniformity in the emitter of our electron gun, which led to a significant variation (approximately 50 %) of the current density across the beam. In order to remedy this problem, we have radically redesigned the input cavity, changing both its geometry and Q factor. These measures should dramatically reduce the probability of instabilities, thus allowing us to remove the experimental limitations imposed on alpha. This new design is presented here. We also describe advanced designs of an output cavity with radial power extraction, and a compact circular to rectangular mode converter. A detailed description of the present experimental setup is given, along with an overview of the power transport system necessary to feed the accelerator with output power from the gyroklystron.en_US
dc.format.extent1256382 bytes
dc.format.extent4755456 bytes
dc.format.mimetypeapplication/pdf
dc.format.mimetypeapplication/msword
dc.language.isoen_US
dc.titleDEVELOPMENT OF A FOUR CAVITY SECOND-HARMONIC GYROKLYSTRON AS DRIVER FOR A LINEAR ACCELERATORen_US
dc.typeDissertationen_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.contributor.departmentPhysicsen_US
dc.subject.pqcontrolledPhysics, Fluid and Plasmaen_US
dc.subject.pqcontrolledPhysics, Radiationen_US
dc.subject.pqcontrolledPhysics, Elementary Particles and High Energyen_US
dc.subject.pquncontrolledgyroklystronen_US
dc.subject.pquncontrolledgyrotronen_US
dc.subject.pquncontrolledhigh poweren_US
dc.subject.pquncontrolledlinear acceleratoren_US
dc.subject.pquncontrolledparticle acceleratorsen_US
dc.subject.pquncontrolledRF sourcesen_US


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