Theory and mitigation of electron back-bombardment in thermionic cathode radio frequency guns
| dc.contributor.author | Edelen, Jonathan Paul, author | |
| dc.contributor.author | Milton, Stephen, advisor | |
| dc.contributor.author | Biedron, Sandra, advisor | |
| dc.contributor.author | Notaros, Branislav, committee member | |
| dc.contributor.author | Johnson, Thomas, committee member | |
| dc.date.accessioned | 2015-08-28T14:35:15Z | |
| dc.date.available | 2015-08-28T14:35:15Z | |
| dc.date.issued | 2015 | |
| dc.description.abstract | Photocathode RF guns are currently the standard for high- power, low-emittance beam generation in free-electron lasers. These devices require the use of high-power lasers (which are bulky and expensive to operate) and high-quantum-efficiency cathodes (which have limited lifetimes requiring frequent replacement). The use of RF-gated thermionic cathodes enables operation without a large drive laser and with long lifetimes. One major limitation of RF-gated thermionic cathodes is that electrons emitted late in the RF period will not gain enough energy to exit the gun before being accelerated back towards the cathode by the change in sign of the RF field. These electrons deposit their kinetic energy on the cathode surface in the form of heat, limiting the ability to control the output current from the cathode. This dissertation is aimed at understanding the fundamental design factors that drive the back-bombardment process and at exploring novel techniques to reduce its impact on a high-current system. This begins with the development of analytic models that predict the back-bombardment process in single-cell guns. These models are compared with simulation and with a measurement taken at a specific facility. This is followed by the development of analytic models that predict the effects of space-charge on back-bombardment. These models are compared with simulations. This is followed by an analysis of how the addition of multiple cells will impact the back-bombardment process. Finally, a two-frequency gun is studied for its ability to mitigate the back-bombardment process. This dissertation provides new insight on how the back-bombardment process scales as a function of the beam parameters and how space-charge affects this process. Additionally this dissertation shows how a second frequency can be used to mitigate the back-bombardment effect. | |
| dc.format.medium | born digital | |
| dc.format.medium | doctoral dissertations | |
| dc.identifier | Edelen_colostate_0053A_13106.pdf | |
| dc.identifier.uri | http://hdl.handle.net/10217/167135 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation.ispartof | 2000-2019 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.subject | particle accelerator | |
| dc.subject | electron gun | |
| dc.subject | thermionic cathode | |
| dc.title | Theory and mitigation of electron back-bombardment in thermionic cathode radio frequency guns | |
| dc.type | Text | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). | |
| thesis.degree.discipline | Electrical and Computer Engineering | |
| thesis.degree.grantor | Colorado State University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Doctor of Philosophy (Ph.D.) |
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