IPAC2018 - List of Authors (Gessner, S.J.)

Paper	Title	Page
TUPML022	Assessment of Transverse Instabilities in Proton Driven Hollow Plasma Wakefield Acceleration	1581
	Y. M. Li, G.X. Xia, Y. Zhao UMAN, Manchester, United Kingdom S.J. Gessner CERN, Geneva, Switzerland
	Hollow plasma has been introduced into the proton-driven plasma wakefield accelerators to overcome the issue of beam quality degradation caused by the nonlinear transverse wakefields varying in radius and time in uniform plasma. It has been demonstrated in simulations that the electrons can be accelerated to energy frontier with well-preserved beam quality in a long hollow plasma channel. However, this scheme imposes tight requirements on the beam-channel alignment. Otherwise asymmetric transverse wakefields along the axis are induced, which could distort the driving bunch and deteriorate the witness beam quality. In this paper, by means of the 2D cartesian particle-in-cell simulations, we examine the potentially detrimental effects induced by the driving beam-channel offset and initial driver tilt, and then propose and assess the solutions to these driver inaccuracy issues.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML022
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TUPML049	Comparison of Fourier Signal and Error Analysis Techniques for Identifying the Self-Modulation Frequency of a Proton Bunch	1651
	S.J. Gessner CERN, Geneva, Switzerland
	The AWAKE experiment uses an ultra-high energy proton beam to create large amplitude wakefields for accelerating electrons in plasma. The proton beam is much longer than the plasma wavelength, and must be formed into small, sub- wavelength sized beamlets before it can effectively drive the wake. These beamlets are referred to as micro-bunches and are formed by the plasma self-modulation instability. An im- portant aspect of AWAKE is to measure the depth, frequency, and stability of the modulation, as this provides critical in- formation for establishing the presence of a high-amplitude wakefield driven by a self-modulation proton bunch. This paper discusses Fourier Analysis techniques for measuring the modulation frequency and compares error estimation techniques that work for both small and large datasets. On behalf of the AWAKE Collaboration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML049
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WEPAF070	Commissioning of Beam Instrumentation at the CERN AWAKE Facility After Integration of the Electron Beam Line	1993
	I. Gorgisyan, C. Bracco, S. Burger, S. Döbert, S.J. Gessner, E. Gschwendtner, L.K. Jensen, S. Jensen, S. Mazzoni, D. Medina, K. Pepitone, L. Søby, F.M. Velotti, M. Wendt CERN, Geneva, Switzerland M. Cascella, S. Jolly, F. Keeble, M. Wing UCL, London, United Kingdom V.A. Verzilov TRIUMF, Vancouver, Canada
	The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) is a project at CERN aiming to accelerate an electron bunch in a plasma wakefield driven by a proton bunch. The plasma is induced in a 10 m long Rubidium vapour cell using a pulsed Ti:Sapphire laser, with the wakefield formed by a proton bunch from the CERN SPS. A 16 MeV electron bunch is simultaneously injected into the plasma cell to be accelerated by the wakefield to energies in GeV range over this short distance. After successful runs with the proton and laser beams, the electron beam line was installed and commissioned at the end of 2017 to produce and inject a suitable electron bunch into the plasma cell. To achieve the goals of the experiment, it is important to have reliable beam instrumentation measuring the various parameters of the proton, electron and laser beams such as transverse position, transverse profile as well as temporal synchronization. This contribution presents the status of the beam instrumentation in AWAKE, including the new instruments incorporated into the system for measurements with the electron beam line, and reports on the performance achieved during the AWAKE runs in 2017. Gschwendtner E., et al. "AWAKE, the Advanced Proton Driven Plasma Wakefield Experiment at CERN", NIM A 829 (2016)76-82
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF070
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THZGB5	APS/DPB Thesis Award Talk 2017: Spencer Gessner
	S.J. Gessner CERN, Geneva, Switzerland
	APS/DPB Thesis Award Talk 2017: Spencer Gessner
	Slides THZGB5 [11.328 MB]
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Paper

Title

Page

Assessment of Transverse Instabilities in Proton Driven Hollow Plasma Wakefield Acceleration

1581

Y. M. Li, G.X. Xia, Y. Zhao
UMAN, Manchester, United Kingdom
S.J. Gessner
CERN, Geneva, Switzerland

Hollow plasma has been introduced into the proton-driven plasma wakefield accelerators to overcome the issue of beam quality degradation caused by the nonlinear transverse wakefields varying in radius and time in uniform plasma. It has been demonstrated in simulations that the electrons can be accelerated to energy frontier with well-preserved beam quality in a long hollow plasma channel. However, this scheme imposes tight requirements on the beam-channel alignment. Otherwise asymmetric transverse wakefields along the axis are induced, which could distort the driving bunch and deteriorate the witness beam quality. In this paper, by means of the 2D cartesian particle-in-cell simulations, we examine the potentially detrimental effects induced by the driving beam-channel offset and initial driver tilt, and then propose and assess the solutions to these driver inaccuracy issues.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML022

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TUPML049

Comparison of Fourier Signal and Error Analysis Techniques for Identifying the Self-Modulation Frequency of a Proton Bunch

1651

S.J. Gessner
CERN, Geneva, Switzerland

The AWAKE experiment uses an ultra-high energy proton beam to create large amplitude wakefields for accelerating electrons in plasma. The proton beam is much longer than the plasma wavelength, and must be formed into small, sub- wavelength sized beamlets before it can effectively drive the wake. These beamlets are referred to as micro-bunches and are formed by the plasma self-modulation instability. An im- portant aspect of AWAKE is to measure the depth, frequency, and stability of the modulation, as this provides critical in- formation for establishing the presence of a high-amplitude wakefield driven by a self-modulation proton bunch. This paper discusses Fourier Analysis techniques for measuring the modulation frequency and compares error estimation techniques that work for both small and large datasets.
On behalf of the AWAKE Collaboration.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML049

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WEPAF070

Commissioning of Beam Instrumentation at the CERN AWAKE Facility After Integration of the Electron Beam Line

1993

I. Gorgisyan, C. Bracco, S. Burger, S. Döbert, S.J. Gessner, E. Gschwendtner, L.K. Jensen, S. Jensen, S. Mazzoni, D. Medina, K. Pepitone, L. Søby, F.M. Velotti, M. Wendt
CERN, Geneva, Switzerland
M. Cascella, S. Jolly, F. Keeble, M. Wing
UCL, London, United Kingdom
V.A. Verzilov
TRIUMF, Vancouver, Canada

The Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) is a project at CERN aiming to accelerate an electron bunch in a plasma wakefield driven by a proton bunch*. The plasma is induced in a 10 m long Rubidium vapour cell using a pulsed Ti:Sapphire laser, with the wakefield formed by a proton bunch from the CERN SPS. A 16 MeV electron bunch is simultaneously injected into the plasma cell to be accelerated by the wakefield to energies in GeV range over this short distance. After successful runs with the proton and laser beams, the electron beam line was installed and commissioned at the end of 2017 to produce and inject a suitable electron bunch into the plasma cell. To achieve the goals of the experiment, it is important to have reliable beam instrumentation measuring the various parameters of the proton, electron and laser beams such as transverse position, transverse profile as well as temporal synchronization. This contribution presents the status of the beam instrumentation in AWAKE, including the new instruments incorporated into the system for measurements with the electron beam line, and reports on the performance achieved during the AWAKE runs in 2017.
* Gschwendtner E., et al. "AWAKE, the Advanced Proton Driven Plasma Wakefield Experiment at CERN", NIM A 829 (2016)76-82

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF070

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THZGB5

APS/DPB Thesis Award Talk 2017: Spencer Gessner

S.J. Gessner
CERN, Geneva, Switzerland

APS/DPB Thesis Award Talk 2017: Spencer Gessner

Slides THZGB5 [11.328 MB]

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