Resonant excitation of high order modes in the 3.9 GHz cavity of the Linac Coherent Light Source

Lunin, A.; Khabiboulline, T.; Solyak, N.; Суханов, А.; Yakovlev, Vyacheslav

doi:10.1103/physrevaccelbeams.21.022001

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…To provide the required luminosity for a linear collider, it is critical to reduce emittance dilution in the main linac from machine tolerances such as cavity misalignments and imperfections [68,69]. For the C 3 linac, misalignments can arise from individual cavity misalignments and changes in the properties of coupled HOMs in a cryomodule with misaligned and deformed C 3 cavities.…”

Section: Start-to-end Simulationmentioning

confidence: 99%

Status and future plans for C³ R&D

Nanni,

Breidenbach,

et al. 2023

J. Inst.

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C3 is an opportunity to realize an e + e - collider for the study of the Higgs boson at √s = 250 GeV, with a well defined upgrade path to 550 GeV while staying on the same short facility footprint [2,3]. C3 is based on a fundamentally new approach to normal conducting linear accelerators that achieves both high gradient and high efficiency at relatively low cost. Given the advanced state of linear collider designs, the key system that requires technical maturation for C3 is the main linac. This paper presents the staged approach towards a facility to demonstrate C3 technology with both Direct (source and main linac) and Parallel (beam delivery, damping ring, ancillary component) R&D. The primary goal of the C3 Demonstration R&D Plan is to reduce technical and cost risk by building and operating the key components of C3 at an adequate scale. This R&D plan starts with the engineering design, and demonstration of one cryomodule and will culminate in the construction of a 3 cryomodule linac with pre-production prototypes. This R&D program would also demonstrate the linac rf fundamentals including achievable gradient and gradient stability over a full electron bunch train and breakdown rates. It will also investigate beam dynamics including energy spread, wakefields, and emittance growth. This work will be critical to confirm the suitability of the C3 beam parameters for the physics reach and detector performance in preparation for a Conceptual Design Report (CDR), as well as for follow-on technology development and industrialization. The C3 Demonstration R&D Plan will open up significant new scientific and technical opportunities based on development of high-gradient and high-efficiency accelerator technology. It will push this technology to operate both at the GeV scale and mature the technology to be reliable and provide high-brightness electron beams. The timeline for progressing with C3 technology development will be governed by practical limitations on both the technical progress and resource availability. It consists of four stages: Stage 0) Ongoing fundamental R&D on structure prototypes, damping and vibrations. Stage 1) Advancing the engineering maturity of the design and developing start-to-end simulations including space-charge and wakefield effects. This stage will include testing of strucutres operating at cryogenic temperatures. Beam tests would be performed with high beam current to test full beam loading. Stage 2) Production and testing of the first cryomodule at cryogenic temperatures. This would provide sufficient experimental data to compile a CDR and it is anticipated for Stage 2 to last 3 years and to culminate with the transport of photo-electrons through the first cryomodule. Stage 3) Updates to the engineering design of the cryomodules, production of the second and third cryomodule and their installation. Lower charge and lower emittance beams will be used to investigate emittance growth. The successful full demonstration of the 3 cryomodules to deliver up to a 3 GeV beam and achieve the C3five gradient will allow a comprehensive and robust evaluation of the technical design of C3 as well as mitigate technical, schedule, and cost risks required to proceed with a Technical Design Report (TDR).

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Section: Start-to-end Simulationmentioning

confidence: 99%

Status and future plans for C³ R&D

Nanni,

Breidenbach,

et al. 2023

J. Inst.

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“…By doing the eigenmode spectrum calculation of a series of randomly generated cavities we can accumulate the data for the evaluation the HOM statistics. We used the proposed technique for HOMs analysis in high energy (HE) 650 MHz cavities of the PIP-II linac and 3.9 GHz cavities of the LCLS-II project [10,11]. Finally, we compared our results with available HOMs experimental data and present the procedure for the estimations of cumulative probabilities of resonant HOM losses and the beam emittance dilution in the string of SRF cavities.…”

Section: -----+---mentioning

confidence: 99%

“…Evidently the experimental results are in perfect agreement with both theoretical and numerical predictions. For the second time we calculated HOM statistics for the third harmonic cavity of LCLS-II project [11]. Figure 8 shows frequency standard deviations for modes in the first monopole band.…”

Section: Application Of the Stochastic Analysis Of Hom Spectrummentioning

confidence: 99%

Statistical Analysis of the Eigenmode Spectrum in the SRF Cavities with Mechanical Imperfections [PowerPoint]

Lunin

Khabiboulline

Solyak

et al. 2018

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The superconducting radio frequency (SRF) technology is progressing rapidly over the last decades toward high accelerating gradients and low surface resistance making feasible the particle accelerators operation with high beam currents and long duty factors. However, the coherent RF losses due to high order modes (HOMs) excitation becomes a limiting factor for these regimes. In spite of the operating mode, which is tuned separately, the parameters of HOMs vary from one cavity to another due to finite mechanical tolerances during cavities fabrication. It is vital to know in advance the spread of HOM parameters in order to predict unexpected cryogenic losses, overheating of beam line components and to keep stable beam dynamics. In this paper we present the method of generating the unique cavity geometry with imperfections while preserving operating mode frequency and field flatness. Based on the eigenmode spectrum calculation of a series of randomly generated cavities, we can accumulate the data for the evaluation of the HOM statistics. Finally, we describe the procedure for the estimation of the probability of the resonant HOM losses in the SRF resonators. The study of these effects leads to specifications of SRF cavity and cryomodule and can significantly impact the efficiency and reliability of the machine operation.

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