PAC2013 - List of Authors (Wu, G.)

Paper	Title	Page
WEPAC01	Time-Resolved Temperature Mapping System for the APS Deflecting Cavity	784
	Y. Yang TUB, Beijing, People's Republic of China P. Dhakal, J.D. Mammosser, H. Wang JLAB, Newport News, Virginia, USA J.D. Fuerst, J.P. Holzbauer, J.A. Kaluzny, A. Nassiri, G. Wu, Y. Yang ANL, Argonne, USA
	Time-resolved temperature mapping of a superconducting cavity can give valuable information on the limiting process of the cavity performance. A fast temperature mapping system has been developed at Argonne National Laboratory (ANL) for a superconducting deflecting cavity test. The time resolution of the temperature mapping could be up to 50 us. Not only the spatial distribution of surface heating but also the thermodynamics can be recorded, which helps to understand the limitation mechanism. This new temperature mapping system has helped us to understand the rf performance limitations during the cavity vertical tests. Based on the findings from the temperature mapping, proper cavity treatment has been applied and the cavity performances have been improved.

WEPAC02	Mode Damping Measurement for the APS Deflecting Cavity	787
	Y. Yang, A. Nassiri, T.L. Smith, G.J. Waldschmidt, G. Wu ANL, Argonne, USA H. Wang JLAB, Newport News, Virginia, USA Y. Yang TUB, Beijing, People's Republic of China
	The Advanced Photon Source has considered using a deflecting-cavity-based scheme to produce short pulse xrays. A deflecting cavity design has been completed. To verify the simulation result on this cavity, a copper prototype of the design has been fabricated for bench measurement. In this paper, we report our measurement results on this cavity. All the cavity modes below 5 GHz were identified by comparing the field distributions with calculations along different beam paths. After adding the damper, the measured Qexts of those modes were consistent with calculated values, which demonstrated that the cavity damping scheme was sufficient to reduce the wake impedances well below the safety thresholds.

WEPAC44	Higher Order Modes Damping and Multipacting Analysis for the SPX Deflecting Cavity in APS Upgrade	874
	C.-K. Ng, Z. Li, L. Xiao SLAC, Menlo Park, California, USA A. Nassiri, G.J. Waldschmidt, G. Wu ANL, Argonne, USA R.A. Rimmer, H. Wang JLAB, Newport News, Virginia, USA
	Funding: Work supported by US DOE under contract number DE-AC02-06CH11357. A single-cell superconducting deflecting cavity operating at 2.815 GHz has been proposed and designed for the Short Pulse X-ray (SPX) project for the Advanced Photon Source (APS) upgrade. Each deflecting cavity is equipped with one fundamental power coupler (FPC), one lower order mode (LOM) coupler, and two higher order mode (HOM) couplers to achieve the stringent damping requirements for the unwanted modes. Using the electromagnetic simulation suite ACE3P, HOM damping will be calculated for the cavity including the full engineering design waveguide configurations and rf windows. Trapped modes in the bellows located in the beampipes connecting the cavities in a cryomodule will be computed and their effects on heating evaluated. Furthermore, multipacting activities at the end groups of the cavity will be identified to assess possible problems during high power processing.

Paper

Title

Page

Time-Resolved Temperature Mapping System for the APS Deflecting Cavity

784

Y. Yang
TUB, Beijing, People's Republic of China
P. Dhakal, J.D. Mammosser, H. Wang
JLAB, Newport News, Virginia, USA
J.D. Fuerst, J.P. Holzbauer, J.A. Kaluzny, A. Nassiri, G. Wu, Y. Yang
ANL, Argonne, USA

Time-resolved temperature mapping of a superconducting cavity can give valuable information on the limiting process of the cavity performance. A fast temperature mapping system has been developed at Argonne National Laboratory (ANL) for a superconducting deflecting cavity test. The time resolution of the temperature mapping could be up to 50 us. Not only the spatial distribution of surface heating but also the thermodynamics can be recorded, which helps to understand the limitation mechanism. This new temperature mapping system has helped us to understand the rf performance limitations during the cavity vertical tests. Based on the findings from the temperature mapping, proper cavity treatment has been applied and the cavity performances have been improved.

WEPAC02

Mode Damping Measurement for the APS Deflecting Cavity

787

Y. Yang, A. Nassiri, T.L. Smith, G.J. Waldschmidt, G. Wu
ANL, Argonne, USA
H. Wang
JLAB, Newport News, Virginia, USA
Y. Yang
TUB, Beijing, People's Republic of China

The Advanced Photon Source has considered using a deflecting-cavity-based scheme to produce short pulse xrays. A deflecting cavity design has been completed. To verify the simulation result on this cavity, a copper prototype of the design has been fabricated for bench measurement. In this paper, we report our measurement results on this cavity. All the cavity modes below 5 GHz were identified by comparing the field distributions with calculations along different beam paths. After adding the damper, the measured Qexts of those modes were consistent with calculated values, which demonstrated that the cavity damping scheme was sufficient to reduce the wake impedances well below the safety thresholds.

WEPAC44

Higher Order Modes Damping and Multipacting Analysis for the SPX Deflecting Cavity in APS Upgrade

874

C.-K. Ng, Z. Li, L. Xiao
SLAC, Menlo Park, California, USA
A. Nassiri, G.J. Waldschmidt, G. Wu
ANL, Argonne, USA
R.A. Rimmer, H. Wang
JLAB, Newport News, Virginia, USA

Funding: Work supported by US DOE under contract number DE-AC02-06CH11357.
A single-cell superconducting deflecting cavity operating at 2.815 GHz has been proposed and designed for the Short Pulse X-ray (SPX) project for the Advanced Photon Source (APS) upgrade. Each deflecting cavity is equipped with one fundamental power coupler (FPC), one lower order mode (LOM) coupler, and two higher order mode (HOM) couplers to achieve the stringent damping requirements for the unwanted modes. Using the electromagnetic simulation suite ACE3P, HOM damping will be calculated for the cavity including the full engineering design waveguide configurations and rf windows. Trapped modes in the bellows located in the beampipes connecting the cavities in a cryomodule will be computed and their effects on heating evaluated. Furthermore, multipacting activities at the end groups of the cavity will be identified to assess possible problems during high power processing.