Final published version
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Creating Exact Multipolar Fields with Azimuthally Modulated RF Cavities
AU - Wroe, Laurence
AU - Sheehy, Suzanne
AU - Apsimon, Robert
PY - 2022/6/10
Y1 - 2022/6/10
N2 - RF cavities used in modern particle accelerators operate in TMm10-like modes composed of a single, dominant multipole of order m; m = 0 modes are used for the longitudinal acceleration of a particle beam and m ̸= 0 modes for controlling transverse beam dynamics. The practical design of the latter, however, can be complex and require extensive analysis through the iteration of both approximate mathematical models and computationally expensive simulations to optimise the performance of the structure. In this paper we present a new, systematic method for designing azimuthally modulated RF cavities that support modes composed of any number and magnitude of user-specified transverse multipoles, either with or without a longitudinally accelerating component. Two case studies are presented of RF cavity designs that support modes composed of a longitudinally accelerating field in addition to a single transverse multipole, and designs that support modes composed of two transverse multipoles. We discuss generalising the discoveries and conclusions from the two case studies to designing cavities that support modes composed of any number of multipoles. The theoretical work is verified with analysis of 3D simulations and experimental measurements are presented of a cavity operating in a 3 GHz mode that simultaneously longitudinally accelerates and transversely focuses a beam.
AB - RF cavities used in modern particle accelerators operate in TMm10-like modes composed of a single, dominant multipole of order m; m = 0 modes are used for the longitudinal acceleration of a particle beam and m ̸= 0 modes for controlling transverse beam dynamics. The practical design of the latter, however, can be complex and require extensive analysis through the iteration of both approximate mathematical models and computationally expensive simulations to optimise the performance of the structure. In this paper we present a new, systematic method for designing azimuthally modulated RF cavities that support modes composed of any number and magnitude of user-specified transverse multipoles, either with or without a longitudinally accelerating component. Two case studies are presented of RF cavity designs that support modes composed of a longitudinally accelerating field in addition to a single transverse multipole, and designs that support modes composed of two transverse multipoles. We discuss generalising the discoveries and conclusions from the two case studies to designing cavities that support modes composed of any number of multipoles. The theoretical work is verified with analysis of 3D simulations and experimental measurements are presented of a cavity operating in a 3 GHz mode that simultaneously longitudinally accelerates and transversely focuses a beam.
U2 - 10.1103/PhysRevAccelBeams.25.062001
DO - 10.1103/PhysRevAccelBeams.25.062001
M3 - Journal article
VL - 25
JO - Physical Review Accelerators and Beams
JF - Physical Review Accelerators and Beams
SN - 2469-9888
IS - 6
M1 - 062001
ER -