IPAC2016 - List of Authors (Wu, X.W.)

Paper	Title	Page
TUPOW014	Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun	1769
	J.H. Shao, H.B. Chen, J. Shi, X.W. Wu TUB, Beijing, People's Republic of China S.P. Antipov, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA W. Gai ANL, Argonne, Illinois, USA F.Y. Wang SLAC, Menlo Park, California, USA
	Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW014
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOW015	Experiment of High Resolution Field Emission Imaging in an rf Photocathode Gun	1772
	J.H. Shao, H.B. Chen, J. Shi, X.W. Wu TUB, Beijing, People's Republic of China S.P. Antipov, S.V. Baryshev, C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA M.E. Conde, W. Gai, G. Ha, E.E. Wisniewski ANL, Argonne, Illinois, USA F.Y. Wang SLAC, Menlo Park, California, USA
	The first in situ high resolution field emission (FE) imaging experiment has been carried out on an L-band photocathode gun test stand at Argonne Wakefield Accelerator facility (AWA). Separated strong emitters have been observed to dominate the field emission. Field enhancement factor, beta, of small regions on the cathode has been measured with the imaging system. It is shown that most strong emitters overlaps with the high beta regions. The post surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred. Detailed results are presented in this paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW015
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOW016	Development of a C-Band 4/8 Mev Dual-Energy Accelerator for Cargo Inspection System	1775
	J.H. Shao, H.B. Chen, W.-H. Huang, Q.X. Jin, Y.H. Liu, J. Shi, C.-X. Tang, X.W. Wu TUB, Beijing, People's Republic of China
	Modern cargo inspection system applies dual-energy X-ray for material discrimination. Based on the com-pact C-band 6 MeV standing-wave accelerating struc-tures developed at Tsinghua University, a compact C-band 4/8 MeV dual-energy accelerator has been pro-posed, fabricated and tested. Compared with that of the conventional S-band 3/6 MeV dual-energy accelera-tor at Tsinghua University, the volume and the weight of the C-band one has been reduced by ~40% and ~30%, respectively. Detailed review of this C-band dual-energy accelerator is present in the paper.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW016
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOR041	High Gradient Properties of a CLIC Prototype Accelerating Structure made by Tsinghua University	3874
	X.W. Wu, H.B. Chen, J. Shi TUB, Beijing, People's Republic of China T. Higo, S. Matsumoto KEK, Ibaraki, Japan W. Wuensch CERN, Geneva, Switzerland
	A CLIC prototype structure, T24_THU_#1, was recently high-gradient tested at KEK X-band test stand, Nextef. The copper parts of this 24-cell TW structure were delivered from CERN, were bonded and brazed, bench-tested and tuned in Tsinghua University. The aim of this test was not only to verify the cavity high-gradient properties under 100 MV/m but also to study the breakdown phenomenon in high gradient. High power test results were presented and breakdown rate under 100 MV/m was compared to previously-tested CLIC prototype structures. The assembly capability of Tsinghua University for X-band high gradient structures was validated by the good high gradient performance of T24_THU_#1.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR041
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOR042	New Quantity Describing the Pulse Shape Dependence of the High Gradient Limit in Single Cell Standing-Wave Accelerating Structures	3878
	J. Shi, H.B. Chen, X.W. Wu TUB, Beijing, People's Republic of China V.A. Dolgashev SLAC, Menlo Park, California, USA A. Grudiev, W. Wuensch CERN, Geneva, Switzerland Y. Higashi KEK, Ibaraki, Japan B. Spataro INFN/LNF, Frascati (Roma), Italy
	A new quantity has been developed to study the relationship among the breakdown rate, the pulse width and the gradient. Difference pulse shapes can be treated by introducing a Green's function. This paper describes the quantity and the results while it is applied to the data of many high-power test runs of different single-cell standing wave accelerating structures. A remarkably similar relationship between the new quantity and breakdown rate is observed from all of the test results.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR042
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOR043	High Power Test of X-band Single Cell HOM-free Choke-mode Damped Accelerating Structure made by Tsinghua University	3881
	X.W. Wu, H.B. Chen, J. Shi TUB, Beijing, People's Republic of China T. Abe, T. Higo KEK, Ibaraki, Japan W. Wuensch, H. Zha CERN, Geneva, Switzerland
	As an alternative design for CLIC main accelerating structures, X-band choke-mode damped structures had been studied for several years. However, the performance of choke-mode cavity under high power is still in lack of research. Two standing wave single cell choke-mode damped accelerating structures with different choke dimensions which are working at 11.424 GHz were designed, manufactured and bench tested by accelerator group in Tsinghua University. High power test was carried out on it to study the breakdown phenomenon in high gradient. A single cell structure without choke which almost has the same inner dimension as choke-mode cavity will also be tested to make a comparison and study how the choke affects high-gradient properties.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR043
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Simulation of High Resolution Field Emission Imaging in an rf Photocathode Gun

1769

J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
TUB, Beijing, People's Republic of China
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
W. Gai
ANL, Argonne, Illinois, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

Precisely locating field emission (FE) emitters on a realistic surface in rf structures is technically chal-lenging in general due to the wide emitting phase and the broad energy spread. A method to achieve in situ high resolution FE imaging has been proposed by using solenoids and a collimator to select electrons emitted at certain phases. The phase selection criterion and imaging properties have been studied by the beam dynamics code ASTRA. Detailed results are presented in this paper.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW014

Export •

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

TUPOW015

Experiment of High Resolution Field Emission Imaging in an rf Photocathode Gun

1772

J.H. Shao, H.B. Chen, J. Shi, X.W. Wu
TUB, Beijing, People's Republic of China
S.P. Antipov, S.V. Baryshev, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, G. Ha, E.E. Wisniewski
ANL, Argonne, Illinois, USA
F.Y. Wang
SLAC, Menlo Park, California, USA

The first in situ high resolution field emission (FE) imaging experiment has been carried out on an L-band photocathode gun test stand at Argonne Wakefield Accelerator facility (AWA). Separated strong emitters have been observed to dominate the field emission. Field enhancement factor, beta, of small regions on the cathode has been measured with the imaging system. It is shown that most strong emitters overlaps with the high beta regions. The post surface examinations reveal the origins of ~75% strong emitters overlap with the spots where rf breakdown have occurred. Detailed results are presented in this paper.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW015

Export •

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

TUPOW016

Development of a C-Band 4/8 Mev Dual-Energy Accelerator for Cargo Inspection System

1775

J.H. Shao, H.B. Chen, W.-H. Huang, Q.X. Jin, Y.H. Liu, J. Shi, C.-X. Tang, X.W. Wu
TUB, Beijing, People's Republic of China

Modern cargo inspection system applies dual-energy X-ray for material discrimination. Based on the com-pact C-band 6 MeV standing-wave accelerating struc-tures developed at Tsinghua University, a compact C-band 4/8 MeV dual-energy accelerator has been pro-posed, fabricated and tested. Compared with that of the conventional S-band 3/6 MeV dual-energy accelera-tor at Tsinghua University, the volume and the weight of the C-band one has been reduced by ~40% and ~30%, respectively. Detailed review of this C-band dual-energy accelerator is present in the paper.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW016

Export •

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

THPOR041

High Gradient Properties of a CLIC Prototype Accelerating Structure made by Tsinghua University

3874

X.W. Wu, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China
T. Higo, S. Matsumoto
KEK, Ibaraki, Japan
W. Wuensch
CERN, Geneva, Switzerland

A CLIC prototype structure, T24_THU_#1, was recently high-gradient tested at KEK X-band test stand, Nextef. The copper parts of this 24-cell TW structure were delivered from CERN, were bonded and brazed, bench-tested and tuned in Tsinghua University. The aim of this test was not only to verify the cavity high-gradient properties under 100 MV/m but also to study the breakdown phenomenon in high gradient. High power test results were presented and breakdown rate under 100 MV/m was compared to previously-tested CLIC prototype structures. The assembly capability of Tsinghua University for X-band high gradient structures was validated by the good high gradient performance of T24_THU_#1.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR041

Export •

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

THPOR042

New Quantity Describing the Pulse Shape Dependence of the High Gradient Limit in Single Cell Standing-Wave Accelerating Structures

3878

J. Shi, H.B. Chen, X.W. Wu
TUB, Beijing, People's Republic of China
V.A. Dolgashev
SLAC, Menlo Park, California, USA
A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland
Y. Higashi
KEK, Ibaraki, Japan
B. Spataro
INFN/LNF, Frascati (Roma), Italy

A new quantity has been developed to study the relationship among the breakdown rate, the pulse width and the gradient. Difference pulse shapes can be treated by introducing a Green's function. This paper describes the quantity and the results while it is applied to the data of many high-power test runs of different single-cell standing wave accelerating structures. A remarkably similar relationship between the new quantity and breakdown rate is observed from all of the test results.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR042

Export •

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

THPOR043

High Power Test of X-band Single Cell HOM-free Choke-mode Damped Accelerating Structure made by Tsinghua University

3881

X.W. Wu, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China
T. Abe, T. Higo
KEK, Ibaraki, Japan
W. Wuensch, H. Zha
CERN, Geneva, Switzerland

As an alternative design for CLIC main accelerating structures, X-band choke-mode damped structures had been studied for several years. However, the performance of choke-mode cavity under high power is still in lack of research. Two standing wave single cell choke-mode damped accelerating structures with different choke dimensions which are working at 11.424 GHz were designed, manufactured and bench tested by accelerator group in Tsinghua University. High power test was carried out on it to study the breakdown phenomenon in high gradient. A single cell structure without choke which almost has the same inner dimension as choke-mode cavity will also be tested to make a comparison and study how the choke affects high-gradient properties.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR043

Export •

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