SRF2013 - List of Authors (Liu, K.X.)

Paper

Title

Page

Commissioning and Operation of DC-SRF Injector

53

K.X. Liu, J.E. Chen, L.W. Feng, J.K. Hao, S. Huang, L. Lin, S.W. Quan, F. Wang, Zh.W. Wang, X.D. Wen, H.M. Xie, K. Zhao, F. Zhu
PKU, Beijing, People's Republic of China

As a new and compact injector with medium beam current, the DC-SRF injector at Peking University has been upgraded recently mainly on DC part and heat loading. With a new 20kW solid state RF power source, an improved LLRF system and related diagnostic devices on the new beam line, a series of experiments have been carried out for stably operating the DC-SRF injector at 2K temperature. The description of the system, experiment process and results will be presented.

Slides MOIOB04 [4.992 MB]

TUIOA06

Research on Field Emission and Dark Current in ILC Cavities

392

Y.M. Li, K.X. Liu
PKU, Beijing, People's Republic of China
R.L. Geng, A.D. Palczewski
JLAB, Newport News, Virginia, USA

Funding: Work supported by DOE. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Field emission and dark current are issues of concern for SRF cavity performance and SRF linac operation. Complete understanding and reliable control of the issue are still needed, especially in full-scale multi-cell cavities. Our work aims at developing a generic procedure for finding an active field emitter in a multi-cell cavity and benchmarking the procedure through cavity vertical test. Our ultimate goal is to provide feedback to cavity preparation and cavity string assembly in order to reduce or eliminate filed emission in SRF cavities. Systematic analysis of behaviors of field emitted electrons is obtained by ACE3P developed by SLAC. Experimental benchmark of the procedure was carried out in a 9-cell cavity vertical test at JLab. The energy spectrum of Bremsstrahlung X-rays is measured using a NaI(Tl) detector. The end-point energy in the X-ray energy spectrum is taken as the highest kinetic electron energy to predict longitudinal position of the active field emitter. Angular location of the field emitter is determined by an array of silicon diodes around irises of the cavity. High-resolution optical inspection was conducted at the predicted field emitter location.

Slides TUIOA06 [4.565 MB]

THP011

Improving Gradient of 9-cell SRF Cavities at Peking University

914

J.K. Hao, J.E. Chen, L. Lin, K.X. Liu, X.Y. Lu, S.W. Quan, F. Wang, H.M. Xie, B.C. Zhang, K. Zhao, F. Zhu
PKU, Beijing, People's Republic of China

Four 9-cell TESLA superconducting cavities have been fabricated with Ningxia OTIC niobium material, including two fine grain and two large grain niobium cavities. The cavities have been tested after post treatments. At the early stage (PKU1 and PKU2), the gradient was about 23 MV/m. The gradient of PKU3 reached 28.4 MV/m, but the Q is low. The newest large grain 1.3 GHz 9-cell TESLA type SRF cavity (PKU4) has been made with careful control of machining, and improved surface treatment and electron beam welding. The maximum of gradient is 32.4 MV/m and the intrinsic quality factor (Q0) is 1.3x10¹⁰, which meet the requirement for ILC both in accelerating gradient and intrinsic quality factor.

Paper	Title	Page
MOIOB04	Commissioning and Operation of DC-SRF Injector	53
	K.X. Liu, J.E. Chen, L.W. Feng, J.K. Hao, S. Huang, L. Lin, S.W. Quan, F. Wang, Zh.W. Wang, X.D. Wen, H.M. Xie, K. Zhao, F. Zhu PKU, Beijing, People's Republic of China
	As a new and compact injector with medium beam current, the DC-SRF injector at Peking University has been upgraded recently mainly on DC part and heat loading. With a new 20kW solid state RF power source, an improved LLRF system and related diagnostic devices on the new beam line, a series of experiments have been carried out for stably operating the DC-SRF injector at 2K temperature. The description of the system, experiment process and results will be presented.
	Slides MOIOB04 [4.992 MB]

TUIOA06	Research on Field Emission and Dark Current in ILC Cavities	392
	Y.M. Li, K.X. Liu PKU, Beijing, People's Republic of China R.L. Geng, A.D. Palczewski JLAB, Newport News, Virginia, USA
	Funding: Work supported by DOE. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Field emission and dark current are issues of concern for SRF cavity performance and SRF linac operation. Complete understanding and reliable control of the issue are still needed, especially in full-scale multi-cell cavities. Our work aims at developing a generic procedure for finding an active field emitter in a multi-cell cavity and benchmarking the procedure through cavity vertical test. Our ultimate goal is to provide feedback to cavity preparation and cavity string assembly in order to reduce or eliminate filed emission in SRF cavities. Systematic analysis of behaviors of field emitted electrons is obtained by ACE3P developed by SLAC. Experimental benchmark of the procedure was carried out in a 9-cell cavity vertical test at JLab. The energy spectrum of Bremsstrahlung X-rays is measured using a NaI(Tl) detector. The end-point energy in the X-ray energy spectrum is taken as the highest kinetic electron energy to predict longitudinal position of the active field emitter. Angular location of the field emitter is determined by an array of silicon diodes around irises of the cavity. High-resolution optical inspection was conducted at the predicted field emitter location.
	Slides TUIOA06 [4.565 MB]

THP011	Improving Gradient of 9-cell SRF Cavities at Peking University	914
	J.K. Hao, J.E. Chen, L. Lin, K.X. Liu, X.Y. Lu, S.W. Quan, F. Wang, H.M. Xie, B.C. Zhang, K. Zhao, F. Zhu PKU, Beijing, People's Republic of China
	Four 9-cell TESLA superconducting cavities have been fabricated with Ningxia OTIC niobium material, including two fine grain and two large grain niobium cavities. The cavities have been tested after post treatments. At the early stage (PKU1 and PKU2), the gradient was about 23 MV/m. The gradient of PKU3 reached 28.4 MV/m, but the Q is low. The newest large grain 1.3 GHz 9-cell TESLA type SRF cavity (PKU4) has been made with careful control of machining, and improved surface treatment and electron beam welding. The maximum of gradient is 32.4 MV/m and the intrinsic quality factor (Q0) is 1.3x10¹⁰, which meet the requirement for ILC both in accelerating gradient and intrinsic quality factor.