SRF2015 - List of Authors (Xiao, L.)

Paper	Title	Page
THPB008	RF Simulations for an LCLS-II 3rd Harmonic Cavity Cyromodule	1078
	L. Xiao, C. Adolphsen, Z. Li, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	The FNAL designed 3.9 GHz third harmonic cavity for XFEL will be used in LCLS-II for linearizing the longitudinal beam profile. The 3.9 GHz SRF cavity is scaled down from the 1.3 GHz TESLA cavity shape, but has a disproportionately large beampipe radius for better higher-order mode (HOM) damping. The HOM and fundamental power (FPC) couplers will generate asymmetric field in the beam region, and thereby dilute the beam emittance. Meanwhile, due to the large beampipe, all but a few of the HOMs are above the beampipe cutoff. Thus the HOM damping analyses need to be performed in a full cryomodule, rather than in an individual cavity. The HOM damping in a 4-cavity cryomodule was investigated to determine possible trapped modes using the parallel electromagnetic code suite ACE3P developed at SLAC. The coupler RF kicks induced by the HOM and FPC couplers in the 3.9 GHz cavity were evaluated. A possible cavity-to-cavity arrangement is proposed which could provide effective cancellation of these RF kicks. In this paper we present and discuss the RF simulation results in the 3.9 GHz third harmonic cavity cryomodule. Work supported by Department of Energy under contract Number DE-AC02-76SF00515.
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THPB077	Modified TTF3 Couplers for LCLS-II	1306
	C. Adolphsen, K. Fant, Z. Li, C.D. Nantista, G. Stupakov, J. Tice, F.Y. Wang, L. Xiao SLAC, Menlo Park, California, USA I.V. Gonin, K. Premo, N. Solyak Fermilab, Batavia, Illinois, USA
	The LCLS-II 4 GeV SC electron linac will use 280 TESLA cavities and TTF3 couplers, modified for CW operation with input power up to about 7 kW. The coupler modifications include shortening the antenna to achieve higher Qext and thickening the copper plating on the warm section inner conductor to lower the peak temperature. Another change is the use a waveguide transition box that is machined out of a solid piece of aluminum, significantly reducing its cost and improving its fit to the warm coupler window section. This paper describes the changes, simulations of the coupler operation (heat loads and temperatures), rf processing results and CW tests with LCLS-II dressed cavities.
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Paper

Title

Page

RF Simulations for an LCLS-II 3rd Harmonic Cavity Cyromodule

1078

L. Xiao, C. Adolphsen, Z. Li, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The FNAL designed 3.9 GHz third harmonic cavity for XFEL will be used in LCLS-II for linearizing the longitudinal beam profile. The 3.9 GHz SRF cavity is scaled down from the 1.3 GHz TESLA cavity shape, but has a disproportionately large beampipe radius for better higher-order mode (HOM) damping. The HOM and fundamental power (FPC) couplers will generate asymmetric field in the beam region, and thereby dilute the beam emittance. Meanwhile, due to the large beampipe, all but a few of the HOMs are above the beampipe cutoff. Thus the HOM damping analyses need to be performed in a full cryomodule, rather than in an individual cavity. The HOM damping in a 4-cavity cryomodule was investigated to determine possible trapped modes using the parallel electromagnetic code suite ACE3P developed at SLAC. The coupler RF kicks induced by the HOM and FPC couplers in the 3.9 GHz cavity were evaluated. A possible cavity-to-cavity arrangement is proposed which could provide effective cancellation of these RF kicks. In this paper we present and discuss the RF simulation results in the 3.9 GHz third harmonic cavity cryomodule.
Work supported by Department of Energy under contract Number DE-AC02-76SF00515.

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THPB077

Modified TTF3 Couplers for LCLS-II

1306

C. Adolphsen, K. Fant, Z. Li, C.D. Nantista, G. Stupakov, J. Tice, F.Y. Wang, L. Xiao
SLAC, Menlo Park, California, USA
I.V. Gonin, K. Premo, N. Solyak
Fermilab, Batavia, Illinois, USA

The LCLS-II 4 GeV SC electron linac will use 280 TESLA cavities and TTF3 couplers, modified for CW operation with input power up to about 7 kW. The coupler modifications include shortening the antenna to achieve higher Qext and thickening the copper plating on the warm section inner conductor to lower the peak temperature. Another change is the use a waveguide transition box that is machined out of a solid piece of aluminum, significantly reducing its cost and improving its fit to the warm coupler window section. This paper describes the changes, simulations of the coupler operation (heat loads and temperatures), rf processing results and CW tests with LCLS-II dressed cavities.

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reference for this paper to ※ BibTeX, ※ LaTeX, ※ Text, ※ RIS/RefMan, ※ EndNote (xml)