Calculation of RF pulse evolution due to dispersion in travelling wave linacs using Fourier methods

Cowie, L. and McKenzie, J. and Burt, G. (2024) Calculation of RF pulse evolution due to dispersion in travelling wave linacs using Fourier methods. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1064: 169464. ISSN 0168-9002

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Abstract

An rf pulse propagating through a travelling wave linac can be seen to evolve due to dispersion. To accurately predict the field amplitude experienced by electron bunches travelling through the cavity, this pulse evolution must be well known. Here we present an method to predict the pulse evolution using Fourier methods. The method requires two inputs to calculate the dispersion: the group velocity as a function of cell number, and the phase advance. Attenuation is included in the model with the addition of a third input: the cavity Q0. The method is faster and more simple than 3D modelling, and allows subtle details of the pulse evolution to be revealed, without the need to know the exact dimensions of the structure. A synchronism condition can be added to predict the voltage experienced by a particle beam. The model is tested on the first CLARA linac, and shows good agreement both with measurements of the rf pulse and with measurements of the beam momentum as the time of beam injection is varied.

Item Type:
Journal Article
Journal or Publication Title:
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Additional Information:
Export Date: 6 June 2024 CODEN: NIMAE Correspondence Address: Cowie, L.; ASTeC, Daresbury, Cheshire, United Kingdom; email: louise.cowie@stfc.ac.uk
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3100/3105
Subjects:
?? analytical modellingrf dispersionrf structurestravelling wave linacs3d modelingforecastinglinear acceleratorswave transmissionanalytical modelingfield amplitudesfourier methodsmeasurements ofpulse evolutionrf pulserf structuretraveling wave linactravellin ??
ID Code:
221153
Deposited By:
Deposited On:
06 Jun 2024 10:25
Refereed?:
Yes
Published?:
Published
Last Modified:
07 Jun 2024 03:15