IPAC2018 - List of Authors (Li, Z.)

Paper	Title	Page
TUPMF081	Microphonic Detuning Induced Coupler Kick Variation at LCLS-II	1456
	T. Hellert DESY, Hamburg, Germany W. Ackermann, H. De Gersem TEMF, TU Darmstadt, Darmstadt, Germany C. Adolphsen, Z. Li, C.E. Mayes SLAC, Menlo Park, California, USA
	The LCLS-II free-electron laser will be an upgrade of the existing Linac Coherent Light Source (LCLS), including a 4 GeV CW superconducting linac based on the TESLA technology. The high quality factor of the cavity makes it very sensitive to vibrations. The shift of its eigenfrequency (i.e., detuning) will be compensated by the power source in order to assure a constant accelerating voltage. Significant variations of the forward power are expected which result in coupler kick variations induced by the fundamental power coupler. In this work we estimate the magnitude of trajectory jitter caused by these variations. High precision 3D field maps including standing and traveling-wave components for a cavity with the LCLS-II coupler design are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF081
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THPAL080	Parallel-Feed SRF Accelerator Structures	3835
	P.B. Welander, Z. Li, M.H. Nasr, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515. Development of SRF accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed NCRF structure at SLAC has served as a proof-of-concept. Applied to SRF, such a structure could dramatically reduce power consumption while boosting the achievable gradient. Instead of coupled elliptical cells, our structure employs isolated reentrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Such a structure has been fabricated from bulk Cu and tested at SLAC - designed for X-band, it operates at a record gradient of 150 MV/m. Adapting to SRF at 1.3 GHz and fabricating from Nb, such a cavity could achieve more than 50% lower RF loss and 40% higher gradient compared to the TESLA cavity. We will describe our simulations and propose an experimental roadmap for demonstrating this technology.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL080
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Microphonic Detuning Induced Coupler Kick Variation at LCLS-II

1456

T. Hellert
DESY, Hamburg, Germany
W. Ackermann, H. De Gersem
TEMF, TU Darmstadt, Darmstadt, Germany
C. Adolphsen, Z. Li, C.E. Mayes
SLAC, Menlo Park, California, USA

The LCLS-II free-electron laser will be an upgrade of the existing Linac Coherent Light Source (LCLS), including a 4 GeV CW superconducting linac based on the TESLA technology. The high quality factor of the cavity makes it very sensitive to vibrations. The shift of its eigenfrequency (i.e., detuning) will be compensated by the power source in order to assure a constant accelerating voltage. Significant variations of the forward power are expected which result in coupler kick variations induced by the fundamental power coupler. In this work we estimate the magnitude of trajectory jitter caused by these variations. High precision 3D field maps including standing and traveling-wave components for a cavity with the LCLS-II coupler design are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF081

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPAL080

Parallel-Feed SRF Accelerator Structures

3835

P.B. Welander, Z. Li, M.H. Nasr, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Department of Energy, Laboratory Directed Research and Development program at SLAC National Accelerator Laboratory, under contract DE-AC02-76SF00515.
Development of SRF accelerator technology that enables both higher gradient and higher efficiency is crucial for future machines. While much of the recent R&D focus has been on materials and surface science, our aim is to optimize the cavity geometry to maximize performance with current materials. The recent demonstration of a highly efficient parallel-feed NCRF structure at SLAC has served as a proof-of-concept. Applied to SRF, such a structure could dramatically reduce power consumption while boosting the achievable gradient. Instead of coupled elliptical cells, our structure employs isolated reentrant cells. To feed RF power to the cavities, each cell is directly coupled to an integrated manifold. The structure is made in two parts, split along the beam axis, which are then joined. Such a structure has been fabricated from bulk Cu and tested at SLAC - designed for X-band, it operates at a record gradient of 150 MV/m. Adapting to SRF at 1.3 GHz and fabricating from Nb, such a cavity could achieve more than 50% lower RF loss and 40% higher gradient compared to the TESLA cavity. We will describe our simulations and propose an experimental roadmap for demonstrating this technology.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL080

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)