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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 - Design and testing of a four rod crab cavity for High Luminosity LHC
AU - Hall, Ben
AU - Burt, Graeme Campbell
AU - Apsimon, Robert James
AU - Lingwood, Chris
AU - Tutte, Adam
AU - Grudiev, Alexej
AU - Macpherson, Alec
AU - Navarro-Tapia, Maria
AU - Calaga, Rama
AU - Hernández-Chahín, Kareem
AU - Appleby, Robert
AU - Goudket, Philippe
PY - 2017/1/3
Y1 - 2017/1/3
N2 - A 4-rod deflecting structure is proposed as a possible crab cavity design for the LHC high luminosity upgrade. Crab cavities are required for the LHC luminosity upgrade to provide a greater bunch overlap in the presence of a crossing angle, but must fit in the existing limited space. The structure has two parallel sections consisting of two longitudinally opposing quarter-wave rods, where each rod has the opposite charge from each of its nearest neighbors. The structure is transversely compact because the frequency is dependent on the rod lengths rather than the cavity radius. Simulations were undertaken to investigate the effect of rod shape on surface fields, higher order multipole terms and induced wakefields in order to obtain the optimal rod shape. The simulation results presented show that the addition of focus electrodes or by shaping the rods the sextupole contribution of the cavity voltage can be negated; the sextupole contribution is 321.57 mTm/m2, Epeak=27.7 MV/m and Bpeak=63.9 mT at the design voltage of 3 MV. The damping requirements for the LHC are critical and suitable couplers to damp all modes but the operating mode are presented. The results of various testing cycles of the first SRF 4 rod prototype cavity are presented and show that the cavity has reached the required transverse voltage of 3 MV.
AB - A 4-rod deflecting structure is proposed as a possible crab cavity design for the LHC high luminosity upgrade. Crab cavities are required for the LHC luminosity upgrade to provide a greater bunch overlap in the presence of a crossing angle, but must fit in the existing limited space. The structure has two parallel sections consisting of two longitudinally opposing quarter-wave rods, where each rod has the opposite charge from each of its nearest neighbors. The structure is transversely compact because the frequency is dependent on the rod lengths rather than the cavity radius. Simulations were undertaken to investigate the effect of rod shape on surface fields, higher order multipole terms and induced wakefields in order to obtain the optimal rod shape. The simulation results presented show that the addition of focus electrodes or by shaping the rods the sextupole contribution of the cavity voltage can be negated; the sextupole contribution is 321.57 mTm/m2, Epeak=27.7 MV/m and Bpeak=63.9 mT at the design voltage of 3 MV. The damping requirements for the LHC are critical and suitable couplers to damp all modes but the operating mode are presented. The results of various testing cycles of the first SRF 4 rod prototype cavity are presented and show that the cavity has reached the required transverse voltage of 3 MV.
U2 - 10.1103/PhysRevAccelBeams.20.012001
DO - 10.1103/PhysRevAccelBeams.20.012001
M3 - Journal article
VL - 20
JO - Physical Review Special Topics: Accelerators and Beams
JF - Physical Review Special Topics: Accelerators and Beams
SN - 1098-4402
IS - 1
M1 - 012001
ER -