IPAC2016 - List of Authors (Wuensch, W.)

Paper	Title	Page
WEOBB02	Status of Wakefield Monitor Experiments at the CLIC Test Facility	2099
	R.L. Lillestøl, E. Adli, J. Pfingstner University of Oslo, Oslo, Norway N. Aftab, S. Javeed PINSTECH, Islamabad, Pakistan R. Corsini, S. Döbert, W. Farabolini, A. Grudiev, W. Wuensch CERN, Geneva, Switzerland
	For the very low emittance beams in CLIC, it is vital to mitigate emittance growth which leads to reduced luminosity in the detectors. One factor that leads to emittance growth is transverse wakefields in the accelerating structures. In order to combat this the structures must be aligned with a precision of a few um. For achieving this tolerance, accelerating structures are equipped with wakefield monitors that measure higher-order dipole modes excited by the beam when offset from the structure axis. We report on such measurements, performed using prototype CLIC accelerating structures which are part of the module installed in the CLIC Test Facility 3 (CTF3) at CERN. Measurements with and without the drive beam that feeds rf power to the structures are compared. Improvements to the experimental setup are discussed, and finally remaining measurements that should be performed before the completion of the program are summarized.
	Slides WEOBB02 [2.928 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOBB02
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THPMW022	The RF Design of a Compact, High Power Pulse Compressor with a Flat Output Pulse	3591
SUPSS105	use link to see paper's listing under its alternate paper code
	P. Wang, H.B. Chen, J. Shi TUB, Beijing, People's Republic of China I. Syratchev, W. Wuensch, H. Zha CERN, Geneva, Switzerland
	An X-band, high-power pulse compressor, which can produce a flat pulse and a power gain of 4.3, has been designed. The device is compact, with the dimensions of within 1m, and is designed for CLIC first energy stage based on klystrons. We also discuss about a two stage pulse compressor with power gain of 9.18, which may be a candidate of the X-FEL using CLIC X-band linacs and klystrons with low peak power.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW022
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THPOR031	Beam-Loading Effect on Breakdown Rate in High-Gradient Accelerating Structures	3848
	F. Tecker, T. Argyropoulos, N. Catalán Lasheras, R. Corsini, A. Degiovanni, D. Gamba, J. Giner Navarro, A. Grudiev, G. McMonagle, J.L. Navarro Quirante, R. Rajamaki, E. Senes, I. Syratchev, B.J. Woolley, W. Wuensch CERN, Geneva, Switzerland T. Argyropoulos, J. Giner Navarro IFIC, Valencia, Spain A. Degiovanni, J.L. Navarro Quirante ADAM, Geneva, Switzerland D. Gamba JAI, Oxford, United Kingdom R. Rajamaki Aalto University, School of Science and Technology, Aalto, Finland E. Senes Torino University, Torino, Italy J. Tagg National Instruments Switzerland, Ennetbaden, Switzerland
	The Compact Linear Collider (CLIC) study for a future electron-positron collider with a center-of-mass energy up to 3 TeV aims for an accelerating gradient of 100 MV/m. The gradient is limited by RF breakdowns, and the luminosity requirements impose a limit on the admissible RF breakdown rate. RF testing of 12 GHz structure prototypes has shown that gradients in excess of 100 MV/m can be reached with the required breakdown rate. However at CLIC, the structures will be operated with significant beam-loading, modifying the field distribution inside. The effect of the beam-loading must be well understood but has not been previously measured. The commissioning and operation of an experiment to measure the effect of beam-loading on breakdown rate and the measurement results are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR031
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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
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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
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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

Status of Wakefield Monitor Experiments at the CLIC Test Facility

2099

R.L. Lillestøl, E. Adli, J. Pfingstner
University of Oslo, Oslo, Norway
N. Aftab, S. Javeed
PINSTECH, Islamabad, Pakistan
R. Corsini, S. Döbert, W. Farabolini, A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland

For the very low emittance beams in CLIC, it is vital to mitigate emittance growth which leads to reduced luminosity in the detectors. One factor that leads to emittance growth is transverse wakefields in the accelerating structures. In order to combat this the structures must be aligned with a precision of a few um. For achieving this tolerance, accelerating structures are equipped with wakefield monitors that measure higher-order dipole modes excited by the beam when offset from the structure axis. We report on such measurements, performed using prototype CLIC accelerating structures which are part of the module installed in the CLIC Test Facility 3 (CTF3) at CERN. Measurements with and without the drive beam that feeds rf power to the structures are compared. Improvements to the experimental setup are discussed, and finally remaining measurements that should be performed before the completion of the program are summarized.

Slides WEOBB02 [2.928 MB]

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOBB02

Export •

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

THPMW022

The RF Design of a Compact, High Power Pulse Compressor with a Flat Output Pulse

3591

SUPSS105

use link to see paper's listing under its alternate paper code

P. Wang, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China
I. Syratchev, W. Wuensch, H. Zha
CERN, Geneva, Switzerland

An X-band, high-power pulse compressor, which can produce a flat pulse and a power gain of 4.3, has been designed. The device is compact, with the dimensions of within 1m, and is designed for CLIC first energy stage based on klystrons. We also discuss about a two stage pulse compressor with power gain of 9.18, which may be a candidate of the X-FEL using CLIC X-band linacs and klystrons with low peak power.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW022

Export •

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

THPOR031

Beam-Loading Effect on Breakdown Rate in High-Gradient Accelerating Structures

3848

F. Tecker, T. Argyropoulos, N. Catalán Lasheras, R. Corsini, A. Degiovanni, D. Gamba, J. Giner Navarro, A. Grudiev, G. McMonagle, J.L. Navarro Quirante, R. Rajamaki, E. Senes, I. Syratchev, B.J. Woolley, W. Wuensch
CERN, Geneva, Switzerland
T. Argyropoulos, J. Giner Navarro
IFIC, Valencia, Spain
A. Degiovanni, J.L. Navarro Quirante
ADAM, Geneva, Switzerland
D. Gamba
JAI, Oxford, United Kingdom
R. Rajamaki
Aalto University, School of Science and Technology, Aalto, Finland
E. Senes
Torino University, Torino, Italy
J. Tagg
National Instruments Switzerland, Ennetbaden, Switzerland

The Compact Linear Collider (CLIC) study for a future electron-positron collider with a center-of-mass energy up to 3 TeV aims for an accelerating gradient of 100 MV/m. The gradient is limited by RF breakdowns, and the luminosity requirements impose a limit on the admissible RF breakdown rate. RF testing of 12 GHz structure prototypes has shown that gradients in excess of 100 MV/m can be reached with the required breakdown rate. However at CLIC, the structures will be operated with significant beam-loading, modifying the field distribution inside. The effect of the beam-loading must be well understood but has not been previously measured. The commissioning and operation of an experiment to measure the effect of beam-loading on breakdown rate and the measurement results are presented.

DOI •

reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR031

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)