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- V. G. Kurakin
LPI, Moscow
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Energy recovery technique in rf accelerator based applications allows to save rf power and reduce radioactive background as well. In this operation mode used beam is directed back to the accelerator in decelerating rf phase and returns back its kinetic energy to rf field. Thus, rf generator that feeds linac covers cavities walls rf losses only and those part of beam kinetic energy that is used for useful effects production as well. Vector sum of three fields – induced in the linac by an external rf source, accelerated and decelerated beams – determines energy and phase of the beam at linac exit, and together with beam return path optics amplitude and phase of decelerated bunches and hence third component of mentioned sum. In the case of positive sign of this feedback and sufficient amplification in the closed loop just described instability takes place. The main equations that determine beam-rf cavity interaction in energy recovery rf accelerator are derived, single mode approximation being used. Expressions for small deviation from steady state are obtained followed by stability analysis. Results of calculation for increments of instability presented and discussed.
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Slides
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