FEL2019 - List of Keywords (SRF)

Paper	Title	Other Keywords	Page
TUP007	Experience with the Superradiant THz User Facility Driven by a Quasi-CW SRF Accelerator at ELBE	detector, electron, radiation, experiment	56
	M. Bawatna, B.W. Green HZDR, Dresden, Germany
	Instabilities in beam and bunch parameters, such as bunch charge, beam energy or changes in the phase or amplitude of the accelerating field in the RF cavities can be the source of noise in the various secondary sources driven by the electron beam. Bunch charge fluctuations lead to intensity instabilities in the super-radiant THz sources. The primary electron beam driving the light sources has a maximum energy of 40 MeV and a maximum current of 1.6 mA. Depending on the mode of operation required, there are two available injectors in use at ELBE. The first is the thermionic injector, which is used for regular operating modes and supports repetition rates up to 13 MHz and bunch charges up to 100 pC. The second is the SRF photo-cathode injector, which is used for experiments that may require lower emittance or higher bunch charges of up to 1 nC. It has a maximum repetition rate of 13 MHz, which can be adjusted to lower rates if desired, also including different macro pulse modes of operation. In this contribution, we will present our work in the pulse-resolved intensity measurement that allows for correction of intensity instabilities.
	Poster TUP007 [0.658 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP007
About •	paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEA01	Overview of CW RF Guns for Short Wavelength FELs	gun, cathode, FEL, electron	290
	H.J. Qian DESY Zeuthen, Zeuthen, Germany E. Vogel DESY, Hamburg, Germany
	Hard X-ray FELs (XFELs) operating with pulsed RF provide unprecedented peak brilliance for scientific research. Operating the accelerators with CW RF improves the flexibility w.r.t. the available time structure for experiments and opens the next frontier of average brilliance. One of the challenges of CW XFELs is the electron source, which requires both CW operation and highest possible beam quality allowing lasing at shortest wavelengths. The CW mode technically constraints the gun acceleration gradient, which is one of the keys to electron source brightness, so R&D is devoted to CW gun improvements since decades. In this contribution, the worldwide development status of CW RF guns, both normal conducting and superconducting, is reviewed.
	Slides WEA01 [16.329 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEA01
About •	paper received ※ 25 August 2019 paper accepted ※ 07 November 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP026	Preliminary Geometry Optimization of a 3.5-Cell SRF Gun Cavity at ELBE Based on Beam Dynamics	gun, cavity, emittance, electron	374
	K. Zhou, P. Li CAEP/IAE, Mianyang, Sichuan, People’s Republic of China A. Arnold, S. Ma, J. Schaber, J. Teichert, R. Xiang HZDR, Dresden, Germany
	At present, ELBE radiation source at HZDR is optimizing the SRF cavity for the next generation ELBE SRF GUN. This paper presents a preliminary study on the geometry optimization of a 3.5-cell SRF gun cavity based on beam dynamics. By changing the lengths of the half cell and the first TESLA like cell, two new cavity models with higher electric field in the half cell are built and their RF fields are compared with SRF GUN I and SRF GUN II. Through the scanning of the RF phases and the electric fields, the simulation results indicate that new models have smaller transverse emittance at relatively lower electric field gradients and better performance on longitudinal emittance than SRF GUN I and SRF GUN II.
	Poster WEP026 [1.345 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP026
About •	paper received ※ 19 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP043	Multi-Energy Operation Analysis in a Superconducting Linac Based on off-Frequency Detune Method	linac, undulator, electron, acceleration	416
	Z. Zhang, C. Adolphsen, Y. Ding, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	The free-electron laser facilities driven by a superconducting radio-frequency (SRF) linac provide high-repetition-rate electron beam, which makes it feasible to feed multiple undulator lines at the same time. In this paper, we study a method of controlling the beam energy of multiple electron bunches by off-frequency detuning of the SRF linac. Based on the theoretical analysis, we present the optimal solutions of the method and the strategy to allocate linac energy for each possible off-frequency detune. The initial acceleration phases before detuning of the SRF linac can be optimized to reduce the necessary SRF linac energy overhead. We adopt the LCLS-II-HE configuration as an example to discuss possible schemes for two undulator lines.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP043
About •	paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP051	PITZ Experimental Optimization for the Aimed Cathode Gradient of a Superconducting CW RF Gun	emittance, gun, laser, cathode	440
	M. Krasilnikov, P. Boonpornprasert, Y. Chen, G.Z. Georgiev, J.D. Good, M. Groß, P.W. Huang, I.I. Isaev, C. Koschitzki, S. Lal, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany M. Dohlus, E. Vogel DESY, Hamburg, Germany
	A continuous wave (CW) mode operation of the European X-ray Free-Electron Laser (XFEL) is under considerations for a future upgrade. Therefore, a superconducting radio frequency (SRF) CW gun is under experimental development at DESY in Hamburg. Beam dynamics simulations for this setup have been done assuming 100 pC bunch charge and a maximum electric field at the photocathode of 40 MV/m. Experimental studies for these parameters using a normal conducting RF photogun have been performed at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The beam transverse emittance was minimized by optimizing the main photo injector parameters in order to demonstrate the feasibility of generating electron beams with a beam quality required for successful CW operation of the European XFEL for conditions similar to the SRF gun setup.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP051
About •	paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP056	Engineering Design of Low-Emittance DC-SRF Photocathode Injector	cathode, cavity, linac, shielding	460
	Y.Q. Liu, M. Chen, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, S. Zhao PKU, Beijing, People’s Republic of China
	An upgraded version of DC-SRF photocathode injector (DC-SRF-II) is under development at Peking University. The goal is to achieve an emittance below 0.5 mm-mrad at the bunch charge of 100 pC and repetition rate of 1 MHz. The engineering design of the DC-SRF-II photoinjector was accomplished in this May and the fabrication is ongoing now. This paper presents some details of the engineering design.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP056
About •	paper received ※ 19 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEP057	Performance Optimization of Low-Emittance DC-SRF Injector Using Cs2Te Photocathode	emittance, cavity, electron, solenoid	463
	S. Zhao Peking University, Beijing, People’s Republic of China S. Huang, K.X. Liu, Y.Q. Liu, D.M. Ouyang PKU, Beijing, People’s Republic of China
	A low-emittance DC-SRF injector (DC-SRF-II) is under construction at Peking University, in the earlier design of which K2CsSb photocathode was chosen. Recently we changed the cathode to Cs2Te, which is more widely used nowadays, and carried out a detailed performance optimization. In this paper, we present our latest simulation results, which show that an emittance under 0.5 mm-mrad can be achieved at the bunch charge of 100 pC.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP057
About •	paper received ※ 14 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THP008	Design of a Multi-Cell SRF Reduced-Beta Cavity for the Acceleration of Low Energy Electron Beams	cavity, linac, electron, operation	603
	D.B. Bazyl, H. De Gersem, W.F.O. Müller TEMF, TU Darmstadt, Darmstadt, Germany J. Enders, S. Weih TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by DFG (GRK 2128) Recently, the S-DALINAC has successfully passed the first ERL tests. One of the critical requirements for further operation in the ERL regime is minimising the longitudinal energy spread of the electron beam. One of the major sources for the current energy spread at the S-DALINAC is the low energy accelerating section. In order to overcome this problem an SRF reduced-beta cavity has been designed. The new cavity will replace the existing capture section and will allow to accelerate low energy electron beams with a minimised energy spread growth. In this work we discuss the electromagnetic and mechanical design of the SRF 3 GHz 6-cell reduced-beta cavity of elliptic type. In addition, we present the results of beam dynamics simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP008
About •	paper received ※ 19 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Other Keywords

Page

TUP007

Experience with the Superradiant THz User Facility Driven by a Quasi-CW SRF Accelerator at ELBE

detector, electron, radiation, experiment

56

M. Bawatna, B.W. Green
HZDR, Dresden, Germany

Instabilities in beam and bunch parameters, such as bunch charge, beam energy or changes in the phase or amplitude of the accelerating field in the RF cavities can be the source of noise in the various secondary sources driven by the electron beam. Bunch charge fluctuations lead to intensity instabilities in the super-radiant THz sources. The primary electron beam driving the light sources has a maximum energy of 40 MeV and a maximum current of 1.6 mA. Depending on the mode of operation required, there are two available injectors in use at ELBE. The first is the thermionic injector, which is used for regular operating modes and supports repetition rates up to 13 MHz and bunch charges up to 100 pC. The second is the SRF photo-cathode injector, which is used for experiments that may require lower emittance or higher bunch charges of up to 1 nC. It has a maximum repetition rate of 13 MHz, which can be adjusted to lower rates if desired, also including different macro pulse modes of operation. In this contribution, we will present our work in the pulse-resolved intensity measurement that allows for correction of intensity instabilities.

Poster TUP007 [0.658 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-TUP007

About •

paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

Export •

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

WEA01

Overview of CW RF Guns for Short Wavelength FELs

gun, cathode, FEL, electron

290

H.J. Qian
DESY Zeuthen, Zeuthen, Germany
E. Vogel
DESY, Hamburg, Germany

Hard X-ray FELs (XFELs) operating with pulsed RF provide unprecedented peak brilliance for scientific research. Operating the accelerators with CW RF improves the flexibility w.r.t. the available time structure for experiments and opens the next frontier of average brilliance. One of the challenges of CW XFELs is the electron source, which requires both CW operation and highest possible beam quality allowing lasing at shortest wavelengths. The CW mode technically constraints the gun acceleration gradient, which is one of the keys to electron source brightness, so R&D is devoted to CW gun improvements since decades. In this contribution, the worldwide development status of CW RF guns, both normal conducting and superconducting, is reviewed.

Slides WEA01 [16.329 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEA01

About •

paper received ※ 25 August 2019 paper accepted ※ 07 November 2019 issue date ※ 05 November 2019

Export •

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

WEP026

Preliminary Geometry Optimization of a 3.5-Cell SRF Gun Cavity at ELBE Based on Beam Dynamics

gun, cavity, emittance, electron

374

K. Zhou, P. Li
CAEP/IAE, Mianyang, Sichuan, People’s Republic of China
A. Arnold, S. Ma, J. Schaber, J. Teichert, R. Xiang
HZDR, Dresden, Germany

At present, ELBE radiation source at HZDR is optimizing the SRF cavity for the next generation ELBE SRF GUN. This paper presents a preliminary study on the geometry optimization of a 3.5-cell SRF gun cavity based on beam dynamics. By changing the lengths of the half cell and the first TESLA like cell, two new cavity models with higher electric field in the half cell are built and their RF fields are compared with SRF GUN I and SRF GUN II. Through the scanning of the RF phases and the electric fields, the simulation results indicate that new models have smaller transverse emittance at relatively lower electric field gradients and better performance on longitudinal emittance than SRF GUN I and SRF GUN II.

Poster WEP026 [1.345 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP026

About •

paper received ※ 19 August 2019 paper accepted ※ 29 August 2019 issue date ※ 05 November 2019

Export •

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

WEP043

Multi-Energy Operation Analysis in a Superconducting Linac Based on off-Frequency Detune Method

linac, undulator, electron, acceleration

416

Z. Zhang, C. Adolphsen, Y. Ding, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The free-electron laser facilities driven by a superconducting radio-frequency (SRF) linac provide high-repetition-rate electron beam, which makes it feasible to feed multiple undulator lines at the same time. In this paper, we study a method of controlling the beam energy of multiple electron bunches by off-frequency detuning of the SRF linac. Based on the theoretical analysis, we present the optimal solutions of the method and the strategy to allocate linac energy for each possible off-frequency detune. The initial acceleration phases before detuning of the SRF linac can be optimized to reduce the necessary SRF linac energy overhead. We adopt the LCLS-II-HE configuration as an example to discuss possible schemes for two undulator lines.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP043

About •

paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

Export •

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

WEP051

PITZ Experimental Optimization for the Aimed Cathode Gradient of a Superconducting CW RF Gun

emittance, gun, laser, cathode

440

M. Krasilnikov, P. Boonpornprasert, Y. Chen, G.Z. Georgiev, J.D. Good, M. Groß, P.W. Huang, I.I. Isaev, C. Koschitzki, S. Lal, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
M. Dohlus, E. Vogel
DESY, Hamburg, Germany

A continuous wave (CW) mode operation of the European X-ray Free-Electron Laser (XFEL) is under considerations for a future upgrade. Therefore, a superconducting radio frequency (SRF) CW gun is under experimental development at DESY in Hamburg. Beam dynamics simulations for this setup have been done assuming 100 pC bunch charge and a maximum electric field at the photocathode of 40 MV/m. Experimental studies for these parameters using a normal conducting RF photogun have been performed at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The beam transverse emittance was minimized by optimizing the main photo injector parameters in order to demonstrate the feasibility of generating electron beams with a beam quality required for successful CW operation of the European XFEL for conditions similar to the SRF gun setup.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP051

About •

paper received ※ 20 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

Export •

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

WEP056

Engineering Design of Low-Emittance DC-SRF Photocathode Injector

cathode, cavity, linac, shielding

460

Y.Q. Liu, M. Chen, S. Huang, L. Lin, K.X. Liu, S.W. Quan, F. Wang, S. Zhao
PKU, Beijing, People’s Republic of China

An upgraded version of DC-SRF photocathode injector (DC-SRF-II) is under development at Peking University. The goal is to achieve an emittance below 0.5 mm-mrad at the bunch charge of 100 pC and repetition rate of 1 MHz. The engineering design of the DC-SRF-II photoinjector was accomplished in this May and the fabrication is ongoing now. This paper presents some details of the engineering design.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP056

About •

paper received ※ 19 August 2019 paper accepted ※ 26 August 2019 issue date ※ 05 November 2019

Export •

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

WEP057

Performance Optimization of Low-Emittance DC-SRF Injector Using Cs2Te Photocathode

emittance, cavity, electron, solenoid

463

S. Zhao
Peking University, Beijing, People’s Republic of China
S. Huang, K.X. Liu, Y.Q. Liu, D.M. Ouyang
PKU, Beijing, People’s Republic of China

A low-emittance DC-SRF injector (DC-SRF-II) is under construction at Peking University, in the earlier design of which K2CsSb photocathode was chosen. Recently we changed the cathode to Cs2Te, which is more widely used nowadays, and carried out a detailed performance optimization. In this paper, we present our latest simulation results, which show that an emittance under 0.5 mm-mrad can be achieved at the bunch charge of 100 pC.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-WEP057

About •

paper received ※ 14 August 2019 paper accepted ※ 27 August 2019 issue date ※ 05 November 2019

Export •

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

THP008

Design of a Multi-Cell SRF Reduced-Beta Cavity for the Acceleration of Low Energy Electron Beams

cavity, linac, electron, operation

603

D.B. Bazyl, H. De Gersem, W.F.O. Müller
TEMF, TU Darmstadt, Darmstadt, Germany
J. Enders, S. Weih
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG (GRK 2128)
Recently, the S-DALINAC has successfully passed the first ERL tests. One of the critical requirements for further operation in the ERL regime is minimising the longitudinal energy spread of the electron beam. One of the major sources for the current energy spread at the S-DALINAC is the low energy accelerating section. In order to overcome this problem an SRF reduced-beta cavity has been designed. The new cavity will replace the existing capture section and will allow to accelerate low energy electron beams with a minimised energy spread growth. In this work we discuss the electromagnetic and mechanical design of the SRF 3 GHz 6-cell reduced-beta cavity of elliptic type. In addition, we present the results of beam dynamics simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-FEL2019-THP008

About •

paper received ※ 19 August 2019 paper accepted ※ 28 August 2019 issue date ※ 05 November 2019

Export •

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