Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.792227
Title: Parasitic resonances in high power proton linacs : major issues and mitigation techniques
Author: Ainsworth, Rob
ISNI:       0000 0004 8497 8275
Awarding Body: Royal Holloway, University of London
Current Institution: Royal Holloway, University of London
Date of Award: 2014
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Abstract:
Parasitic resonances in superconducting rf cavities may make the beam unstable and increase the cryogenic load in high power proton machines. Therefore, Same Order Modes (SOMs) and Higher Order Modes (HOMs) must be investigated fully in order to determine if damping is required. A beam dynamics code was used developed to study the interaction of these resonances with the beam for various European Spallation Source (ESS) lattices. Each linac design is characterised by the initial kinetic energy of the beam, as well as by the velocity of the beam at each of the points at which the cavity style changes. The scale of the phase-space disruption of the proton pulse is discussed taking into account amplitude and phase errors from the Klystron, injection errors, alignment errors and the frequency spread the SOMs and HOMs. Mitigation techniques using HOM couplers are also investigated for cavities resonating at 704 MHz. Multipacting in these couplers is a concern as thermally induced detuning of the fundamental notch filter has limited the achievable gradient in other high power machines. It is therefore important to avoid potential multipacting conditions during the design phase. Presented here are simulations using the Track3P code developed at SLAC. Multipacting regions are highlighted and the suitability of proposed HOM coupler designs are discussed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.792227  DOI: Not available
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