IPAC2015 - List of Authors (Adli, E.)

Paper	Title	Page
TUYC1	Multi-GeV Electron and Positron Plasma Wakefield Acceleration Results at FACET
	S.J. Gessner, E. Adli, J.M. Allen, C.I. Clarke, J.-P. Delahaye, J.T. Frederico, S.Z. Green, M.J. Hogan, N. Lipkowitz, M.D. Litos, M.P. Schmeltz, D.R. Walz, V. Yakimenko, G. Yocky SLAC, Menlo Park, California, USA E. Adli University of Oslo, Oslo, Norway W. An, C.E. Clayton, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi UCLA, Los Angeles, California, USA M. Downer, R. Zgadzaj The University of Texas at Austin, Austin, Texas, USA W. Lu TUB, Beijing, People's Republic of China P. Muggli MPI, Muenchen, Germany
	Funding: This work performed [in part] under DOE Contract DE-AC02-76SF00515. The FACET accelerator test facility at SLAC hosts a new generation of Plasma Wakefield Acceleration (PWFA) experiments. "Two-bunch" experiments have demonstrated high-gradient, highly efficient energy transfer in a plasma wakefield. I will discuss results of follow-up experiments that use a 1.3 meter long plasma to accelerate witness bunch electrons to even higher energies. In a first, we observed multi-GeV acceleration of positrons in a plasma. This is a critical step in demonstrating the applicability of PWFA for High-Energy Physics applications.
	Slides TUYC1 [8.619 MB]
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MOPJE059	Tests of Wakefield-Free Steering at ATF2	438
	A. Latina, J. Pfingstner, D. Schulte CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway N. Fuster-Martínez IFIC, Valencia, Spain J. Snuverink JAI, Egham, Surrey, United Kingdom
	Charge-dependent effects on the orbit and on the beam size affect the performance of the Accelerator Test Facility (ATF2) in a non-negligible way. Until now small beam sizes have only been achieved running with a beam charge significantly smaller than the nominal value. These detrimental effects on the beam have been attributed to wakefields, in the cavity BPMs, in the multi-Optical Transition Radiation (OTR) systems as well as in other components of the beamline. The successful tests of a Wakefield-free Steering (WFS) algorithm at FACET have encouraged performing tests of the same correction scheme at ATF2. The performance of the algorithm has been simulated in detail, including several realistic imperfection scenarios, including charge-dependent BPMs resolution, and incoming injection error and position jitters, which are described in this paper. Tests of WFS have been performed at ATF2 during December 2014. The results are discussed here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE059
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MOPTY004	Wakefield Monitor Experiments with X-Band Accelerating Structures	947
	R.L. Lillestøl, E. Adli, J. Pfingstner University of Oslo, Oslo, Norway R. Corsini, S. Döbert, W. Farabolini, L. Malina, W. Wuensch CERN, Geneva, Switzerland
	The accelerating structures for CLIC must be aligned with a precision of a few um with respect to the beam trajectory in order to mitigate emittance growth due to transverse wake fields. We report on first results from wake field monitor tests in an X-band structure, with a probe beam at the CLIC Test Facility. The monitors are currently installed in the CLIC Two-Beam Module. In order to fully demonstrate the feasibility of using wakefield monitors for CLIC, the precision of the monitors must be verified using a probe beam while simultaneously filling the structure with high power rf used to drive the accelerating mode. We outline plans to perform such a demonstration in the CLIC Test Facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY004
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MOPTY044	Machine Protection Systems and their Impact on Beam Availability and Accelerator Reliability	1029
	R. Andersson, E. Bargalló, A. Nordt ESS, Lund, Sweden E. Adli University of Oslo, Oslo, Norway
	Over the last decades, the complexity and performance levels of machine protection have developed. The level of reliability and availability analysis prior to operation differs between facilities, just as the pragmatic changes of the machine protection during operation. This paper studies the experience and development of machine protection for some of the state of the art proton and ion accelerators, and how it relates to reducing damage to and downtime of the machine. The findings are discussed and categorized, with emphasis on proton accelerators. The paper is concluded with some recommendations for a future high power linear proton accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY044
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TUBD3	Effects of Accelerating Structures on On-line DFS in the Main Linac of CLIC	1387
	J. Pfingstner, E. Adli University of Oslo, Oslo, Norway D. Schulte CERN, Geneva, Switzerland
	Long-term ground motion will create significant dispersion in the time-scale of hours in the main linac of CLIC. To preserve the emittance to an acceptable level, a dispersion correction with on-line dispersion-free steering (DFS) is inevitable. For this on-line technique, the dispersion has to be measured using beam energy variations of only about one per mil in order to not disturb the operation of the accelerator. For such small energy variations, the interaction of the particle beam and the accelerating structures creates large enough additional signals components in the measured dispersion to cause the dispersion correction to not work properly anymore. In this paper, the additional signals are described and their effect on the DFS algorithm is analysed. Finally, methods for the mitigation of the deteriorating signal components are presented and studied via simulations.
	Slides TUBD3 [1.697 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBD3
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TUPTY056	Beam-Based Measurements of Long Range Transverse Wakefields in CLIC Main Linac Accelerating Structure	2153
	H. Zha, A. Grudiev, A. Latina, D. Schulte, A. Solodko, W. Wuensch CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway G. De Michele EPFL, Lausanne, Switzerland G. De Michele PSI, Villigen PSI, Switzerland N. Lipkowitz, G. Yocky SLAC, Menlo Park, California, USA
	The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures in the main linac. Every accelerating structure cell has four waveguides, terminated with individual RF loads, to damp the unwanted long-range transverse wakefields, in order to maintain beam stability in multi-bunch operation. In order to experimentally verify the calculated suppression of the wakefields, a prototype structure has been built and installed in FACET test facility at SLAC. The results of the measurements of the wakefields in the prototype structure by means of positron and electron bunches are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY056
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WEPWA008	Measuring the Self-modulation Instability of Electron and Positron Bunches in Plasmas	2506
	P. Muggli, O. Reimann MPI-P, München, Germany E. Adli, V.K.B. Olsen University of Oslo, Oslo, Norway J. Allen, S.J. Gessner, S.Z. Green, M.J. Hogan, M.D. Litos, B.D. O'Shea, V. Yakimenko SLAC, Menlo Park, California, USA L.D. Amorim IST, Lisboa, Portugal G. Andonian, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi, O. Williams UCLA, Los Angeles, California, USA N.C. Lopes, L.O. Silva, J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	The self-modulation instability (SMI) * can be used to transform a long, charged particle bunch into a train of periodically spaced shorter bunches. The SMI occurs in a plasma when the plasma wake period is much shorter than the bunch length. The train of short bunches can then resonantly drive wakefields to much larger amplitude that the long bunch can. The SMI will be used in the AWAKE experiment at CERN, where the wakefields will be driven by a high-energy (400GeV) proton bunch. However, most of the SMI physics can be tested with the electron and positron bunches available at SLAC-FACET. * In this case, the bunch is ~10 plasma wavelengths long, but can drive wakefields in the GV/m range. FACET has a meter-long plasma **** and is well equipped in terms of diagnostic for SMI detection: optical transition radiation for transverse bunch profile measurements, coherent transition radiation interferometry for radial modulation period measurements and energy spectrometer for energy loss and gain measurement of the drive bunch particles. The latest experimental results will be presented. * N. Kumar et al., PRL 104, 255003 (2010) AWAKE Collaboration, PPCF 56 084013 (2014) * J. Vieira et al., PoP 19, 063105 (2012) **** S.Z. Green et al., PPCF 56, 084011 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA008
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WEPWA026	Loading of a Plasma-Wakefield Accelerator Section Driven by a Self-Modulated Proton Bunch	2551
	V.K.B. Olsen, E. Adli University of Oslo, Oslo, Norway L.D. Amorim IST, Lisboa, Portugal P. Muggli MPI, Muenchen, Germany J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	We investigate beam loading of a plasma wake driven by a self-modulated proton beam using particle-in-cell simulations for phase III of the AWAKE project. We address the case of injection after the proton beam has already experienced self-modulation in a previous plasma. Optimal parameters for the injected electron bunch in terms of initial beam energy and beam charge density are investigated and evaluated in terms of witness bunch energy and energy spread. An approximate modulated proton beam is emulated in order to reduce computation time in these simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA026
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Paper

Title

Page

TUYC1

Multi-GeV Electron and Positron Plasma Wakefield Acceleration Results at FACET

S.J. Gessner, E. Adli, J.M. Allen, C.I. Clarke, J.-P. Delahaye, J.T. Frederico, S.Z. Green, M.J. Hogan, N. Lipkowitz, M.D. Litos, M.P. Schmeltz, D.R. Walz, V. Yakimenko, G. Yocky
SLAC, Menlo Park, California, USA
E. Adli
University of Oslo, Oslo, Norway
W. An, C.E. Clayton, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
UCLA, Los Angeles, California, USA
M. Downer, R. Zgadzaj
The University of Texas at Austin, Austin, Texas, USA
W. Lu
TUB, Beijing, People's Republic of China
P. Muggli
MPI, Muenchen, Germany

Funding: This work performed [in part] under DOE Contract DE-AC02-76SF00515.
The FACET accelerator test facility at SLAC hosts a new generation of Plasma Wakefield Acceleration (PWFA) experiments. "Two-bunch" experiments have demonstrated high-gradient, highly efficient energy transfer in a plasma wakefield. I will discuss results of follow-up experiments that use a 1.3 meter long plasma to accelerate witness bunch electrons to even higher energies. In a first, we observed multi-GeV acceleration of positrons in a plasma. This is a critical step in demonstrating the applicability of PWFA for High-Energy Physics applications.

Slides TUYC1 [8.619 MB]

Export •

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

MOPJE059

Tests of Wakefield-Free Steering at ATF2

438

A. Latina, J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway
N. Fuster-Martínez
IFIC, Valencia, Spain
J. Snuverink
JAI, Egham, Surrey, United Kingdom

Charge-dependent effects on the orbit and on the beam size affect the performance of the Accelerator Test Facility (ATF2) in a non-negligible way. Until now small beam sizes have only been achieved running with a beam charge significantly smaller than the nominal value. These detrimental effects on the beam have been attributed to wakefields, in the cavity BPMs, in the multi-Optical Transition Radiation (OTR) systems as well as in other components of the beamline. The successful tests of a Wakefield-free Steering (WFS) algorithm at FACET have encouraged performing tests of the same correction scheme at ATF2. The performance of the algorithm has been simulated in detail, including several realistic imperfection scenarios, including charge-dependent BPMs resolution, and incoming injection error and position jitters, which are described in this paper. Tests of WFS have been performed at ATF2 during December 2014. The results are discussed here.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE059

Export •

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

MOPTY004

Wakefield Monitor Experiments with X-Band Accelerating Structures

947

R.L. Lillestøl, E. Adli, J. Pfingstner
University of Oslo, Oslo, Norway
R. Corsini, S. Döbert, W. Farabolini, L. Malina, W. Wuensch
CERN, Geneva, Switzerland

The accelerating structures for CLIC must be aligned with a precision of a few um with respect to the beam trajectory in order to mitigate emittance growth due to transverse wake fields. We report on first results from wake field monitor tests in an X-band structure, with a probe beam at the CLIC Test Facility. The monitors are currently installed in the CLIC Two-Beam Module. In order to fully demonstrate the feasibility of using wakefield monitors for CLIC, the precision of the monitors must be verified using a probe beam while simultaneously filling the structure with high power rf used to drive the accelerating mode. We outline plans to perform such a demonstration in the CLIC Test Facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY004

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MOPTY044

Machine Protection Systems and their Impact on Beam Availability and Accelerator Reliability

1029

R. Andersson, E. Bargalló, A. Nordt
ESS, Lund, Sweden
E. Adli
University of Oslo, Oslo, Norway

Over the last decades, the complexity and performance levels of machine protection have developed. The level of reliability and availability analysis prior to operation differs between facilities, just as the pragmatic changes of the machine protection during operation. This paper studies the experience and development of machine protection for some of the state of the art proton and ion accelerators, and how it relates to reducing damage to and downtime of the machine. The findings are discussed and categorized, with emphasis on proton accelerators. The paper is concluded with some recommendations for a future high power linear proton accelerator.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPTY044

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TUBD3

Effects of Accelerating Structures on On-line DFS in the Main Linac of CLIC

1387

J. Pfingstner, E. Adli
University of Oslo, Oslo, Norway
D. Schulte
CERN, Geneva, Switzerland

Long-term ground motion will create significant dispersion in the time-scale of hours in the main linac of CLIC. To preserve the emittance to an acceptable level, a dispersion correction with on-line dispersion-free steering (DFS) is inevitable. For this on-line technique, the dispersion has to be measured using beam energy variations of only about one per mil in order to not disturb the operation of the accelerator. For such small energy variations, the interaction of the particle beam and the accelerating structures creates large enough additional signals components in the measured dispersion to cause the dispersion correction to not work properly anymore. In this paper, the additional signals are described and their effect on the DFS algorithm is analysed. Finally, methods for the mitigation of the deteriorating signal components are presented and studied via simulations.

Slides TUBD3 [1.697 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBD3

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TUPTY056

Beam-Based Measurements of Long Range Transverse Wakefields in CLIC Main Linac Accelerating Structure

2153

H. Zha, A. Grudiev, A. Latina, D. Schulte, A. Solodko, W. Wuensch
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway
G. De Michele
EPFL, Lausanne, Switzerland
G. De Michele
PSI, Villigen PSI, Switzerland
N. Lipkowitz, G. Yocky
SLAC, Menlo Park, California, USA

The baseline design of CLIC (Compact Linear Collider) uses X-band accelerating structures in the main linac. Every accelerating structure cell has four waveguides, terminated with individual RF loads, to damp the unwanted long-range transverse wakefields, in order to maintain beam stability in multi-bunch operation. In order to experimentally verify the calculated suppression of the wakefields, a prototype structure has been built and installed in FACET test facility at SLAC. The results of the measurements of the wakefields in the prototype structure by means of positron and electron bunches are presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY056

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WEPWA008

Measuring the Self-modulation Instability of Electron and Positron Bunches in Plasmas

2506

P. Muggli, O. Reimann
MPI-P, München, Germany
E. Adli, V.K.B. Olsen
University of Oslo, Oslo, Norway
J. Allen, S.J. Gessner, S.Z. Green, M.J. Hogan, M.D. Litos, B.D. O'Shea, V. Yakimenko
SLAC, Menlo Park, California, USA
L.D. Amorim
IST, Lisboa, Portugal
G. Andonian, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi, O. Williams
UCLA, Los Angeles, California, USA
N.C. Lopes, L.O. Silva, J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

The self-modulation instability (SMI) * can be used to transform a long, charged particle bunch into a train of periodically spaced shorter bunches. The SMI occurs in a plasma when the plasma wake period is much shorter than the bunch length. The train of short bunches can then resonantly drive wakefields to much larger amplitude that the long bunch can. The SMI will be used in the AWAKE experiment at CERN, where the wakefields will be driven by a high-energy (400GeV) proton bunch. ** However, most of the SMI physics can be tested with the electron and positron bunches available at SLAC-FACET. *** In this case, the bunch is ~10 plasma wavelengths long, but can drive wakefields in the GV/m range. FACET has a meter-long plasma **** and is well equipped in terms of diagnostic for SMI detection: optical transition radiation for transverse bunch profile measurements, coherent transition radiation interferometry for radial modulation period measurements and energy spectrometer for energy loss and gain measurement of the drive bunch particles. The latest experimental results will be presented.
* N. Kumar et al., PRL 104, 255003 (2010)
** AWAKE Collaboration, PPCF 56 084013 (2014)
*** J. Vieira et al., PoP 19, 063105 (2012)
**** S.Z. Green et al., PPCF 56, 084011 (2014)

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA008

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WEPWA026

Loading of a Plasma-Wakefield Accelerator Section Driven by a Self-Modulated Proton Bunch

2551

V.K.B. Olsen, E. Adli
University of Oslo, Oslo, Norway
L.D. Amorim
IST, Lisboa, Portugal
P. Muggli
MPI, Muenchen, Germany
J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

We investigate beam loading of a plasma wake driven by a self-modulated proton beam using particle-in-cell simulations for phase III of the AWAKE project. We address the case of injection after the proton beam has already experienced self-modulation in a previous plasma. Optimal parameters for the injected electron bunch in terms of initial beam energy and beam charge density are investigated and evaluated in terms of witness bunch energy and energy spread. An approximate modulated proton beam is emulated in order to reduce computation time in these simulations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA026

Export •

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