IPAC2019 - List of Authors (Li, X.)

Paper	Title	Page
TUPRB018	Design Studies of a Proof-of-Principle Experiment on THz SASE FEL at PITZ	1713
	X. Li, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, 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
	A free-electron laser based THz source is undergoing design studies at the Photo Injector Test facility at DESY in Zeuthen (PITZ). It is considered as a prototype for pump-probe experiments at the European XFEL, benefiting from the fact that the electron beam from the PITZ facility has an identical pulse train structure as the XFEL pulses. In the proposed proof-of-principle experiment, the electron beam (up to 4 nC bunch charge and 200 A peak current) will be accelerated to 16-22 MeV/c to generate SASE radiations in an LCLS-I undulator in the THz range between 60 and 100 µm with an expected energy of up to ~1 mJ/pulse. In this paper, we report our simulations on the optimization of the photo-injector and the design of the transport and matching beamline. Experimental investigations on the generation, characterization and matching of the high charge beam in the existing 22-m-long beamline will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB018
About •	paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPTS012	Emittance Reduction of RF Photoinjector Generated Electron Beams By Transverse Laser Beam Shaping	1958
	M. Groß, P. Boonpornprasert, Y. Chen, J.D. Good, H. Huck, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, S.K. Mohanty, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany I. Will MBI, Berlin, Germany
	Laser pulse shaping is one of the key elements to generate low emittance electron beams with RF photoinjectors. Ultimately high performance can be achieved with ellipsoidal laser pulses, but 3-dimensional shaping is challenging. High beam quality can also be reached by simple transverse pulse shaping, which has demonstrated improved beam emittance compared to a transversely uniform laser in the ‘pancake’ photoemission regime. In this contribution we present the truncation of a Gaussian laser at a radius of approximately one σ in the intermediate (electron bunch length directly after emission about the same as radius) photoemission regime with high acceleration gradients (up to 60 MV/m). This type of electron bunch is used e.g. at the European XFEL and FLASH free electron lasers at DESY, Hamburg site and is being investigated in detail at the Photoinjector Test facility at DESY in Zeuthen (PITZ). Here we present ray-tracing simulations and experimental data of a laser beamline upgrade enabling variable transverse truncation. Initial projected emittance measurements taken with help of this setup are shown, as well as supporting beam dynamics simulations. Additional simulations show the potential for substantial reduction of slice emittance at PITZ.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS012
About •	paper received ※ 24 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPTS014	SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS	1964
SUSPFO016	use link to see paper's listing under its alternate paper code
	P.W. Huang, Y. Chen, J.D. Good, M. Groß, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany D. Filippetto, F. Sannibale LBNL, Berkeley, California, USA C.-X. Tang TUB, Beijing, People’s Republic of China W. Wan ShanghaiTech University, Shanghai, People’s Republic of China
	In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS014
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEZZPLS2	EuPRAXIA, a Step Toward a Plasma-Wakefield Based Accelerator With High Beam Quality	2291
	P.A.P. Nghiem, A. Chancé CEA-IRFU, Gif-sur-Yvette, France D. Alesini, E. Chiadroni, M. Croia, A. Del Dotto, M. Ferrario, A. Giribono, R. Pompili, S. Romeo, V. Shpakov, A. Stella, C. Vaccarezza INFN/LNF, Frascati, Italy A. Aschikhin, R.W. Aßmann, U. Dorda, A. Ferran Pousa, V. Libov, B. Marchetti, A. Martinez de la Ossa, D. Marx, P. Niknejadi, L. Schaper, E.N. Svystun, P.A. Walker, M.K. Weikum, J. Zhu DESY, Hamburg, Germany T. Audet, B. Cros, P. Lee, G. Maynard CNRS LPGP Univ Paris Sud, Orsay, France A. Beck, F. Massimo, A. Specka LLR, Palaiseau, France M. Chen, S.M. Weng Shanghai Jiao Tong University, Shanghai, People’s Republic of China A. Cianchi Università di Roma II Tor Vergata, Roma, Italy J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.-E. Couprie, A. Ghaith, D. Oumbarek Espinos SOLEIL, Gif-sur-Yvette, France G. Dattoli, F. Nguyen ENEA C.R. Frascati, Frascati (Roma), Italy N. Delerue LAL, Orsay, France R.A. Fonseca, L.O. Silva Instituto Superior Tecnico, Lisbon, Portugal L.A. Gizzi, G. Toci, P. Tomassini INO-CNR, Pisa, Italy A. Helm IST-UTL, Lisbon, Portugal B. Hidding Cockcroft Institute, Warrington, Cheshire, United Kingdom S.M. Hooker, R. Walczak Oxford University, Physics Department, Oxford, Oxon, United Kingdom M.G. Ibison, M. Vujanovic, C.P. Welsch, J. Wolfenden The University of Liverpool, Liverpool, United Kingdom D.A. Jaroszynski, F.Y. Li, Z.M. Sheng, S.M. Wiggins, S. Yoffe USTRAT/SUPA, Glasgow, United Kingdom K.O. Kruchinin, A.Y. Molodozhentsev ELI-BEAMS, Prague, Czech Republic L. Labate CNR/IPP, Pisa, Italy X. Li DESY Zeuthen, Zeuthen, Germany F. Mathieu LULI, Palaiseau, France Z. Mazzotta Ecole Polytechnique, Palaiseau, France T.J. Mehrling LBNL, Berkeley, USA A. Mosnier, C. Simon CEA, Gif-sur-Yvette, France A. Mostacci Rome University La Sapienza, Roma, Italy Z. Najmudin Imperial College of Science and Technology, Department of Physics, London, United Kingdom R. Pattathil, D. Symes STFC/RAL, Chilton, Didcot, Oxon, United Kingdom A.R. Rossi INFN-Milano, Milano, Italy T. Silva, J.M. Vieira IPFN, Lisbon, Portugal M.J.V. Streeter JAI, London, United Kingdom D. Terzani UniNa, Napoli, Italy
	Funding: European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782 The EuPRAXIA project aims at designing the world’s first accelerator based on plasma-wakefield advanced technique, which can deliver a 5 GeV electron beam with simultaneously high charge, low emittance and low energy spread to user’s communities. Such challenging objectives can only have a chance to be achieved when particular efforts are dedicated to identify the subsequent issues and to find the way to solve them. Many injection/acceleration schemes and techniques have been explored by means of thorough simulations in more than ten European institutes to sort out the most appropriate ones. The specific issues of high charge, high beam quality and beam extraction then transfer to the user’s applications, have been tackled with many innovative approaches. This article highlights the different advanced methods that have been employed by the EuPRAXIA collaboration and the preliminary results obtained. The needs in terms of laser and plasma parameters for such an accelerator are also summarized. - in 2017: Phys. Plasmas, 24,10,103120; Nat. Commun.8,15705; - in 2018: NIMA, 909,84-89; NIMA, 909,49-53; Phys. Rev.Acc. Beams, 21,111301; NIMA, 909,54-57; Phys. Rev.Acc. Beams, 21,052802; NIMA, 909,282-285
	Slides WEZZPLS2 [5.157 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZZPLS2
About •	paper received ※ 12 April 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPGW006	Avoiding Emittance Degradation When Transferring the Beam From and to a Plasma-Wakefield Stage	3594
	A. Chancé, P.A.P. Nghiem CEA-IRFU, Gif-sur-Yvette, France X. Li DESY Zeuthen, Zeuthen, Germany
	Funding: European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782. The plasma-wakefield acceleration technique is known to provide a very strong accelerating gradient (GV/m), up to three orders of magnitude higher than the conventional RF acceleration technique. The drawback is a relatively higher energy spread and especially a huge beam divergence at the plasma exit, leading to an irremediable and strong emittance degradation right after its extraction from the plasma for transferring it to an application or another plasma stage. In this article, we determine the criteria to be achieved so as to minimize this emittance growth after pointing out all the parameters involved in its mechanism. Then the plasma down ramp profile is studied in a typical configuration of the EuPRAXIA project at 5 GeV. It turns out that no specific profile is needed. For minimizing emittance growth at beam extraction, it is enough to optimize the ramp length so that the Twiss parameter γ is minimized. Finally the design of an optimal transfer line allows showing that the emittance growth can be contained to less than 10% in realistic conditions when transferring the beam to a free electron laser.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW006
About •	paper received ※ 09 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Design Studies of a Proof-of-Principle Experiment on THz SASE FEL at PITZ

1713

X. Li, P. Boonpornprasert, Y. Chen, J.D. Good, M. Groß, H. Huck, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, 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

A free-electron laser based THz source is undergoing design studies at the Photo Injector Test facility at DESY in Zeuthen (PITZ). It is considered as a prototype for pump-probe experiments at the European XFEL, benefiting from the fact that the electron beam from the PITZ facility has an identical pulse train structure as the XFEL pulses. In the proposed proof-of-principle experiment, the electron beam (up to 4 nC bunch charge and 200 A peak current) will be accelerated to 16-22 MeV/c to generate SASE radiations in an LCLS-I undulator in the THz range between 60 and 100 µm with an expected energy of up to ~1 mJ/pulse. In this paper, we report our simulations on the optimization of the photo-injector and the design of the transport and matching beamline. Experimental investigations on the generation, characterization and matching of the high charge beam in the existing 22-m-long beamline will also be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB018

About •

paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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

TUPTS012

Emittance Reduction of RF Photoinjector Generated Electron Beams By Transverse Laser Beam Shaping

1958

M. Groß, P. Boonpornprasert, Y. Chen, J.D. Good, H. Huck, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, G. Loisch, D. Melkumyan, S.K. Mohanty, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, G. Shu, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
I. Will
MBI, Berlin, Germany

Laser pulse shaping is one of the key elements to generate low emittance electron beams with RF photoinjectors. Ultimately high performance can be achieved with ellipsoidal laser pulses, but 3-dimensional shaping is challenging. High beam quality can also be reached by simple transverse pulse shaping, which has demonstrated improved beam emittance compared to a transversely uniform laser in the ‘pancake’ photoemission regime. In this contribution we present the truncation of a Gaussian laser at a radius of approximately one σ in the intermediate (electron bunch length directly after emission about the same as radius) photoemission regime with high acceleration gradients (up to 60 MV/m). This type of electron bunch is used e.g. at the European XFEL and FLASH free electron lasers at DESY, Hamburg site and is being investigated in detail at the Photoinjector Test facility at DESY in Zeuthen (PITZ). Here we present ray-tracing simulations and experimental data of a laser beamline upgrade enabling variable transverse truncation. Initial projected emittance measurements taken with help of this setup are shown, as well as supporting beam dynamics simulations. Additional simulations show the potential for substantial reduction of slice emittance at PITZ.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS012

About •

paper received ※ 24 April 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

Export •

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

TUPTS014

SINGLE SHOT CATHODE TRANSVERSE MOMENTUM IMAGING IN PHOTOINJECTORS

1964

SUSPFO016

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

P.W. Huang, Y. Chen, J.D. Good, M. Groß, I.I. Isaev, C. Koschitzki, M. Krasilnikov, S. Lal, X. Li, O. Lishilin, D. Melkumyan, R. Niemczyk, A. Oppelt, H.J. Qian, H. Shaker, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
D. Filippetto, F. Sannibale
LBNL, Berkeley, California, USA
C.-X. Tang
TUB, Beijing, People’s Republic of China
W. Wan
ShanghaiTech University, Shanghai, People’s Republic of China

In state of the art photoinjector electron sources, cathode performance determines the lower limit of achievable beam emittance. Measuring the thermal emittance at the photocathodes in electron guns is of vital importance for improving the injectors. Traditional methods, like solenoid scan, pepper-pot, need multi-shots and are time-consuming, therefore suffer from machine stability. Here we propose a new method, named cathode transverse momentum imaging. By tuning the gun solenoid focusing, the electrons’ transverse momentum at the cathode is imaged to a downstream screen, which enables a single shot measurement. Several experiments have been done at the Photo Injector Test Facility at DESY in Zeuthen (PITZ) with a Cs2Te cathode. Measurements of cathode transverse momentum, the corresponding spectra, cathode transverse momentum map and its correlation with surface electric field are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS014

About •

paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

Export •

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WEZZPLS2

EuPRAXIA, a Step Toward a Plasma-Wakefield Based Accelerator With High Beam Quality

2291

P.A.P. Nghiem, A. Chancé
CEA-IRFU, Gif-sur-Yvette, France
D. Alesini, E. Chiadroni, M. Croia, A. Del Dotto, M. Ferrario, A. Giribono, R. Pompili, S. Romeo, V. Shpakov, A. Stella, C. Vaccarezza
INFN/LNF, Frascati, Italy
A. Aschikhin, R.W. Aßmann, U. Dorda, A. Ferran Pousa, V. Libov, B. Marchetti, A. Martinez de la Ossa, D. Marx, P. Niknejadi, L. Schaper, E.N. Svystun, P.A. Walker, M.K. Weikum, J. Zhu
DESY, Hamburg, Germany
T. Audet, B. Cros, P. Lee, G. Maynard
CNRS LPGP Univ Paris Sud, Orsay, France
A. Beck, F. Massimo, A. Specka
LLR, Palaiseau, France
M. Chen, S.M. Weng
Shanghai Jiao Tong University, Shanghai, People’s Republic of China
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.-E. Couprie, A. Ghaith, D. Oumbarek Espinos
SOLEIL, Gif-sur-Yvette, France
G. Dattoli, F. Nguyen
ENEA C.R. Frascati, Frascati (Roma), Italy
N. Delerue
LAL, Orsay, France
R.A. Fonseca, L.O. Silva
Instituto Superior Tecnico, Lisbon, Portugal
L.A. Gizzi, G. Toci, P. Tomassini
INO-CNR, Pisa, Italy
A. Helm
IST-UTL, Lisbon, Portugal
B. Hidding
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S.M. Hooker, R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
M.G. Ibison, M. Vujanovic, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
D.A. Jaroszynski, F.Y. Li, Z.M. Sheng, S.M. Wiggins, S. Yoffe
USTRAT/SUPA, Glasgow, United Kingdom
K.O. Kruchinin, A.Y. Molodozhentsev
ELI-BEAMS, Prague, Czech Republic
L. Labate
CNR/IPP, Pisa, Italy
X. Li
DESY Zeuthen, Zeuthen, Germany
F. Mathieu
LULI, Palaiseau, France
Z. Mazzotta
Ecole Polytechnique, Palaiseau, France
T.J. Mehrling
LBNL, Berkeley, USA
A. Mosnier, C. Simon
CEA, Gif-sur-Yvette, France
A. Mostacci
Rome University La Sapienza, Roma, Italy
Z. Najmudin
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R. Pattathil, D. Symes
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
A.R. Rossi
INFN-Milano, Milano, Italy
T. Silva, J.M. Vieira
IPFN, Lisbon, Portugal
M.J.V. Streeter
JAI, London, United Kingdom
D. Terzani
UniNa, Napoli, Italy

Funding: European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782
The EuPRAXIA project aims at designing the world’s first accelerator based on plasma-wakefield advanced technique, which can deliver a 5 GeV electron beam with simultaneously high charge, low emittance and low energy spread to user’s communities. Such challenging objectives can only have a chance to be achieved when particular efforts are dedicated to identify the subsequent issues and to find the way to solve them. Many injection/acceleration schemes and techniques have been explored by means of thorough simulations in more than ten European institutes to sort out the most appropriate ones. The specific issues of high charge, high beam quality and beam extraction then transfer to the user’s applications, have been tackled with many innovative approaches*. This article highlights the different advanced methods that have been employed by the EuPRAXIA collaboration and the preliminary results obtained. The needs in terms of laser and plasma parameters for such an accelerator are also summarized.
*- in 2017: Phys. Plasmas, 24,10,103120; Nat. Commun.8,15705; - in 2018: NIMA, 909,84-89; NIMA, 909,49-53; Phys. Rev.Acc. Beams, 21,111301; NIMA, 909,54-57; Phys. Rev.Acc. Beams, 21,052802; NIMA, 909,282-285

Slides WEZZPLS2 [5.157 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEZZPLS2

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paper received ※ 12 April 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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THPGW006

Avoiding Emittance Degradation When Transferring the Beam From and to a Plasma-Wakefield Stage

3594

A. Chancé, P.A.P. Nghiem
CEA-IRFU, Gif-sur-Yvette, France
X. Li
DESY Zeuthen, Zeuthen, Germany

Funding: European Union’s Horizon 2020 research and innovation programme under grant agreement No. 653782.
The plasma-wakefield acceleration technique is known to provide a very strong accelerating gradient (GV/m), up to three orders of magnitude higher than the conventional RF acceleration technique. The drawback is a relatively higher energy spread and especially a huge beam divergence at the plasma exit, leading to an irremediable and strong emittance degradation right after its extraction from the plasma for transferring it to an application or another plasma stage. In this article, we determine the criteria to be achieved so as to minimize this emittance growth after pointing out all the parameters involved in its mechanism. Then the plasma down ramp profile is studied in a typical configuration of the EuPRAXIA project at 5 GeV. It turns out that no specific profile is needed. For minimizing emittance growth at beam extraction, it is enough to optimize the ramp length so that the Twiss parameter γ is minimized. Finally the design of an optimal transfer line allows showing that the emittance growth can be contained to less than 10% in realistic conditions when transferring the beam to a free electron laser.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW006

About •

paper received ※ 09 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

Export •

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