IPAC2021 - List of Authors (Xia, G.X.)

Paper	Title	Page
MOPAB143	Simulations for MeV Energy Gain in Multi-Micron Vacuum Channel Dielectric Structures Driven by a CO₂ Laser	499
	G. Yadav, O. Apsimon, Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom O. Apsimon, C.P. Welsch, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom G.X. Xia The University of Manchester, Manchester, United Kingdom
	Funding: This work was supported by STFC LIV. DAT under grant agreement ST/P006752/1. This research used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia. Dielectric Laser Accelerators (DLAs) have been demonstrated as a novel scheme for producing high acceleration gradients (~1 GV/m) within the damage threshold of the dielectric. The compactness of the DLAs and the low emittance of the output electron beam make it an attractive candidate for future endoscopic devices to be used in tumor irradiation. However, due to the small accelerating distances(sub-mm), the total energy gain is limited to sub-MeV which remains an obstacle for its realistic applications. Also, these DLAs operate under solid-state lasers with wavelengths near IR (800 nm to 2 um), where required sub-micron vacuum channel at such wavelengths imposes major aperture restrictions for the amount of charge to be accelerated. Here, we present numerical simulation results for a dielectric structure excited by a CO₂ laser with a wavelength of 10.6 um. Upon injecting a 50 MeV electron bunch through a 5.3 um diameter of vacuum channel width, our simulation suggests an energy gain beyond 1 MeV. These results are the initial steps for the realization of an mm-scale DLA capable of producing MeV energy electron beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB143
About •	paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 August 2021
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MOPAB151	A Stable Drive Beam for High Gradient Dielectric Wakefield Acceleration	528
	T.J. Overton, Y.M. Saveliev, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom T.J. Overton, G.X. Xia The University of Manchester, Manchester, United Kingdom T.H. Pacey, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Science and Technology Funding Council (STFC) student grant. A high accelerating gradient, with stable beam transport, is necessary for the next generation of particle accelerators. Dielectric wakefield accelerators are a potential solution to this problem. In these proceedings, we present simulation studies of electron bunches in the self-wake regime inside a planar dielectric structure. This is analogous to driving beams in a dielectric wakefield accelerator. The transverse and longitudinal wake fields are investigated for dielectric plate gaps, various transverse beam sizes, and longitudinal bunch profiles. The effects of these on the stability of drive bunches, and acceleration of a witness bunch, are discussed in the context of electron bunches that can be produced with conventional linac RF technology.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB151
About •	paper received ※ 13 May 2021 paper accepted ※ 07 June 2021 issue date ※ 24 August 2021
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WEPAB174	Study of the Electron Seeded Proton Self-Modulation Using FBPIC	3008
	L. Liang, G.X. Xia The University of Manchester, Manchester, United Kingdom A. Bonatto Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil L. Liang, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work is supported by the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1 In order to make a full use of the whole proton bunch to drive large amplitude plasma wakefields and suppress the uncontrolled growth of any possible instabilities at the head of the proton bunch, the AWAKE Run 2 experiment plans to use an electron bunch to seed the formation of the proton bunch self-modulation. Additionally, a density step in the plasma channel will be used to freeze the selfmodulation process to keep the wakefield amplitude. In this work, numerical simulations performed with FBPIC are used to investigate the electron seeded proton self-modulation and the effect of the plasma density step as well.
	Poster WEPAB174 [1.751 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB174
About •	paper received ※ 10 May 2021 paper accepted ※ 28 June 2021 issue date ※ 24 August 2021
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WEPAB175	Simulation Study of Electron Beam Acceleration with Non-Gaussian Transverse Profiles for AWAKE Run 2	3012
	L. Liang, G.X. Xia The University of Manchester, Manchester, United Kingdom J.P. Farmer MPI-P, München, Germany L. Liang, G.X. Xia Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: The authors would like to acknowledge the support from the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1 In the physics plan for AWAKE Run 2, two known effects, beam loading the longitudinal wakefield and beam matching to the pure plasma ion channel, will be implemented for the better control of electron acceleration. It is founded in our study of beam matching that the transverse profile of the initial witness beam have a significant impact on its acceleration quality. In this paper, particle-in-cell (PIC) simulations are used to study factors that affect the acceleration quality of electron beams with different transverse profiles.
	Poster WEPAB175 [1.860 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB175
About •	paper received ※ 10 May 2021 paper accepted ※ 25 June 2021 issue date ※ 02 September 2021
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MOPAB171	Numerical Simulation on Plasma-Based Beam Dumps Using Smilei	582
	S. Kumar, C. Davut, G.X. Xia UMAN, Manchester, United Kingdom A. Bonatto, C. Davut, L. Liang The University of Manchester, Manchester, United Kingdom A. Bonatto Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil B.S. Nunes IF-UFRGS, Porto Alegre, Brazil R.P. Nunes UFRGS, Porto Alegre, Brazil
	The active plasma beam dump utilizes a laser to generate a plasma wakefield and decelerate an externally injected beam to low energy. We use the particle-in-cell code "Smi-lei" for the investigation of electron beam energy loss in plasma. In this research work, we optimize the laser and plasma parameters to investigate the active plasma beam dump scheme. In doing so, most of the beam energy will be deposited in the plasma. The optimization strategy for the beam energy loss in plasma is presented. A. Bonatto, C. B. Schroeder et al., Physics of Plasmas 22 (8) 083106 (2015). G. Xia, A. Bonatto et al., Instruments 4 (2) 10 (2020). *A Bonatto et al., J. Phys.: Conf. Ser. 1596 012058, 2020.
	Poster MOPAB171 [0.756 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB171
About •	paper received ※ 15 May 2021 paper accepted ※ 24 May 2021 issue date ※ 26 August 2021
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THPAB284	Analytical and Numerical Characterization of Cherenkov Diffraction Radiation as a Longitudinal Electron Bunch Profile Monitor for AWAKE Run 2	4355
	C. Davut, G.X. Xia UMAN, Manchester, United Kingdom O. Apsimon The University of Liverpool, Liverpool, United Kingdom O. Apsimon Cockcroft Institute, Warrington, Cheshire, United Kingdom P. Karataev Royal Holloway, University of London, Surrey, United Kingdom P. Karataev JAI, Egham, Surrey, United Kingdom T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland
	In this paper, CST simulations of the coherent Cherenkov Diffraction Radiation with a range of parameters for different dielectric target materials and geometries are discussed and compared with the theoretical investigation of the Polarization Current Approach to design a prototype of a radiator for the bunch length/profile monitor for AWAKE Run 2. It was found that the result of PCA theory and CST simulation are consistent with each other regarding the shape of the emitted ChDR cone. * Karlovets, D. V. (2011). JETP, 113(1), 27-45. Shevelev, M. V., & Konkov, A. S. (2014). JETP, 118(4), 501-511. * Curcio, A., et al.(2020). PRAB, 23(2), 022802.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB284
About •	paper received ※ 16 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021
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FRXC02	Non Invasive Bunch Length Measurements Exploiting Cherenkov Diffraction Radiation
	S. Mazzoni, M. Bergamaschi, R. Corsini, A. Curcio, W. Farabolini, D. Gamba, L. Garolfi, A. Gilardi, R. Kieffer, M. Krupa, T. Lefèvre, E. Senes, M. Wendt CERN, Geneva, Switzerland A. Curcio NSRC SOLARIS, Kraków, Poland C. Davut, G.X. Xia UMAN, Manchester, United Kingdom W. Farabolini CEA-DRF-IRFU, France K.V. Fedorov, P. Karataev, K. Lekomtsev, C. Pakuza JAI, Oxford, United Kingdom K.V. Fedorov, A. Potylitsyn TPU, Tomsk, Russia J. Gardelle CEA, LE BARP cedex, France P. Karataev Royal Holloway, University of London, Surrey, United Kingdom T.H. Pacey, Y.M. Saveliev STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom A. Schloegelhofer TU Vienna, Wien, Austria E. Senes Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Cherenkov Diffraction Radiation (ChDR) refers to the emission of broadband electromagnetic radiation which occurs when a charged particle propagates at relativistic speed in the vicinity of a dielectric material. At variance with the better-known Cherenkov radiation, ChDR is a non-invasive technique, that is the particle beam does not impinge on the dielectric radiator. ChDR also possesses other interesting features like a relatively high light yield, a broadband spectrum of emission and the emission at a relatively large angle with respect to the beam trajectory. Due to its potential, CERN initiated over the last few years several studies on ChDR-based diagnostics techniques. In this contribution I will focus on the exploitation of ChDR for non-invasive bunch length measurement, from proof of principle tests performed at the CLEAR facility at CERN and CLARA at Daresbury laboratory to current developments for experiments and facilities such as AWAKE and FCC
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Simulations for MeV Energy Gain in Multi-Micron Vacuum Channel Dielectric Structures Driven by a CO₂ Laser

499

G. Yadav, O. Apsimon, Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon, C.P. Welsch, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
G.X. Xia
The University of Manchester, Manchester, United Kingdom

Funding: This work was supported by STFC LIV. DAT under grant agreement ST/P006752/1. This research used the resources of the Supercomputing Laboratory at KAUST in Thuwal, Saudi Arabia.
Dielectric Laser Accelerators (DLAs) have been demonstrated as a novel scheme for producing high acceleration gradients (~1 GV/m) within the damage threshold of the dielectric. The compactness of the DLAs and the low emittance of the output electron beam make it an attractive candidate for future endoscopic devices to be used in tumor irradiation. However, due to the small accelerating distances(sub-mm), the total energy gain is limited to sub-MeV which remains an obstacle for its realistic applications. Also, these DLAs operate under solid-state lasers with wavelengths near IR (800 nm to 2 um), where required sub-micron vacuum channel at such wavelengths imposes major aperture restrictions for the amount of charge to be accelerated. Here, we present numerical simulation results for a dielectric structure excited by a CO₂ laser with a wavelength of 10.6 um. Upon injecting a 50 MeV electron bunch through a 5.3 um diameter of vacuum channel width, our simulation suggests an energy gain beyond 1 MeV. These results are the initial steps for the realization of an mm-scale DLA capable of producing MeV energy electron beams.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB143

About •

paper received ※ 18 May 2021 paper accepted ※ 02 June 2021 issue date ※ 11 August 2021

Export •

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

MOPAB151

A Stable Drive Beam for High Gradient Dielectric Wakefield Acceleration

528

T.J. Overton, Y.M. Saveliev, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom
T.J. Overton, G.X. Xia
The University of Manchester, Manchester, United Kingdom
T.H. Pacey, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Funding Council (STFC) student grant.
A high accelerating gradient, with stable beam transport, is necessary for the next generation of particle accelerators. Dielectric wakefield accelerators are a potential solution to this problem. In these proceedings, we present simulation studies of electron bunches in the self-wake regime inside a planar dielectric structure. This is analogous to driving beams in a dielectric wakefield accelerator. The transverse and longitudinal wake fields are investigated for dielectric plate gaps, various transverse beam sizes, and longitudinal bunch profiles. The effects of these on the stability of drive bunches, and acceleration of a witness bunch, are discussed in the context of electron bunches that can be produced with conventional linac RF technology.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB151

About •

paper received ※ 13 May 2021 paper accepted ※ 07 June 2021 issue date ※ 24 August 2021

Export •

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

WEPAB174

Study of the Electron Seeded Proton Self-Modulation Using FBPIC

3008

L. Liang, G.X. Xia
The University of Manchester, Manchester, United Kingdom
A. Bonatto
Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
L. Liang, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work is supported by the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1
In order to make a full use of the whole proton bunch to drive large amplitude plasma wakefields and suppress the uncontrolled growth of any possible instabilities at the head of the proton bunch, the AWAKE Run 2 experiment plans to use an electron bunch to seed the formation of the proton bunch self-modulation. Additionally, a density step in the plasma channel will be used to freeze the selfmodulation process to keep the wakefield amplitude. In this work, numerical simulations performed with FBPIC are used to investigate the electron seeded proton self-modulation and the effect of the plasma density step as well.

Poster WEPAB174 [1.751 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB174

About •

paper received ※ 10 May 2021 paper accepted ※ 28 June 2021 issue date ※ 24 August 2021

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

WEPAB175

Simulation Study of Electron Beam Acceleration with Non-Gaussian Transverse Profiles for AWAKE Run 2

3012

L. Liang, G.X. Xia
The University of Manchester, Manchester, United Kingdom
J.P. Farmer
MPI-P, München, Germany
L. Liang, G.X. Xia
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: The authors would like to acknowledge the support from the Cockcroft Institute Core Grant and the STFC AWAKE Run 2 grant ST/T001917/1
In the physics plan for AWAKE Run 2, two known effects, beam loading the longitudinal wakefield and beam matching to the pure plasma ion channel, will be implemented for the better control of electron acceleration. It is founded in our study of beam matching that the transverse profile of the initial witness beam have a significant impact on its acceleration quality. In this paper, particle-in-cell (PIC) simulations are used to study factors that affect the acceleration quality of electron beams with different transverse profiles.

Poster WEPAB175 [1.860 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB175

About •

paper received ※ 10 May 2021 paper accepted ※ 25 June 2021 issue date ※ 02 September 2021

Export •

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

MOPAB171

Numerical Simulation on Plasma-Based Beam Dumps Using Smilei

582

S. Kumar, C. Davut, G.X. Xia
UMAN, Manchester, United Kingdom
A. Bonatto, C. Davut, L. Liang
The University of Manchester, Manchester, United Kingdom
A. Bonatto
Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, Brazil
B.S. Nunes
IF-UFRGS, Porto Alegre, Brazil
R.P. Nunes
UFRGS, Porto Alegre, Brazil

The active plasma beam dump utilizes a laser to generate a plasma wakefield and decelerate an externally injected beam to low energy. We use the particle-in-cell code "Smi-lei" for the investigation of electron beam energy loss in plasma. In this research work, we optimize the laser and plasma parameters to investigate the active plasma beam dump scheme. In doing so, most of the beam energy will be deposited in the plasma. The optimization strategy for the beam energy loss in plasma is presented.
*A. Bonatto, C. B. Schroeder et al., Physics of Plasmas 22 (8) 083106 (2015).
*G. Xia, A. Bonatto et al., Instruments 4 (2) 10 (2020).
*A Bonatto et al., J. Phys.: Conf. Ser. 1596 012058, 2020.

Poster MOPAB171 [0.756 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB171

About •

paper received ※ 15 May 2021 paper accepted ※ 24 May 2021 issue date ※ 26 August 2021

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THPAB284

Analytical and Numerical Characterization of Cherenkov Diffraction Radiation as a Longitudinal Electron Bunch Profile Monitor for AWAKE Run 2

4355

C. Davut, G.X. Xia
UMAN, Manchester, United Kingdom
O. Apsimon
The University of Liverpool, Liverpool, United Kingdom
O. Apsimon
Cockcroft Institute, Warrington, Cheshire, United Kingdom
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
P. Karataev
JAI, Egham, Surrey, United Kingdom
T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland

In this paper, CST simulations of the coherent Cherenkov Diffraction Radiation with a range of parameters for different dielectric target materials and geometries are discussed and compared with the theoretical investigation of the Polarization Current Approach to design a prototype of a radiator for the bunch length/profile monitor for AWAKE Run 2. It was found that the result of PCA theory and CST simulation are consistent with each other regarding the shape of the emitted ChDR cone.
* Karlovets, D. V. (2011). JETP, 113(1), 27-45.
** Shevelev, M. V., & Konkov, A. S. (2014). JETP, 118(4), 501-511.
*** Curcio, A., et al.(2020). PRAB, 23(2), 022802.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB284

About •

paper received ※ 16 May 2021 paper accepted ※ 14 July 2021 issue date ※ 10 August 2021

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

FRXC02

Non Invasive Bunch Length Measurements Exploiting Cherenkov Diffraction Radiation

S. Mazzoni, M. Bergamaschi, R. Corsini, A. Curcio, W. Farabolini, D. Gamba, L. Garolfi, A. Gilardi, R. Kieffer, M. Krupa, T. Lefèvre, E. Senes, M. Wendt
CERN, Geneva, Switzerland
A. Curcio
NSRC SOLARIS, Kraków, Poland
C. Davut, G.X. Xia
UMAN, Manchester, United Kingdom
W. Farabolini
CEA-DRF-IRFU, France
K.V. Fedorov, P. Karataev, K. Lekomtsev, C. Pakuza
JAI, Oxford, United Kingdom
K.V. Fedorov, A. Potylitsyn
TPU, Tomsk, Russia
J. Gardelle
CEA, LE BARP cedex, France
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
T.H. Pacey, Y.M. Saveliev
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Schloegelhofer
TU Vienna, Wien, Austria
E. Senes
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Cherenkov Diffraction Radiation (ChDR) refers to the emission of broadband electromagnetic radiation which occurs when a charged particle propagates at relativistic speed in the vicinity of a dielectric material. At variance with the better-known Cherenkov radiation, ChDR is a non-invasive technique, that is the particle beam does not impinge on the dielectric radiator. ChDR also possesses other interesting features like a relatively high light yield, a broadband spectrum of emission and the emission at a relatively large angle with respect to the beam trajectory. Due to its potential, CERN initiated over the last few years several studies on ChDR-based diagnostics techniques. In this contribution I will focus on the exploitation of ChDR for non-invasive bunch length measurement, from proof of principle tests performed at the CLEAR facility at CERN and CLARA at Daresbury laboratory to current developments for experiments and facilities such as AWAKE and FCC

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