NAPAC2016 - List of Keywords (wakefield)

Paper	Title	Other Keywords	Page
MOPOB57	Wakefield Excitation in Power Extraction Cavity of Co-Linear X-Band Energy Booster in Time Domain With ACE3P	ion, cavity, impedance, extraction	195
	T. Sipahi, S. Biedron, S.V. Milton CSU, Fort Collins, Colorado, USA
	We provide the general concept and the design details of our proposed Co-linear X-band Energy Booster (CXEB). Here, using the time domain solver T3P of the ACE3P Suite we provide the single bunch and multiple bunch wakefield excitation mechanism for the power build up when using a symmetric Gaussian bunch distribution in our traveling wave (TW) X-band power extraction cavity (PEC). Finally, we determine the achievable X-band power at the end of the PEC structure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB57
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TUA2IO01	AWAKE - A Proton Driven Plasma Wakefield Acceleration Experiment at CERN	ion, plasma, proton, electron	266
	A. Caldwell MPI-P, München, Germany
	It is the aim of the AWAKE project at CERN to demonstrate the acceleration of electrons in the wake created by a proton beam passing through plasma. The proton beam will be modulated as a result of the transverse two-stream instability into a series ofμbunches that will then drive strong wakefields. The wakefields will then be used to accelerate electrons with GV/m strength fields. The AWAKE experiment is currently being commissioned and first data taking is expected this year. The status of the experimental program is described as well as first thoughts on future steps.
	Slides TUA2IO01 [24.428 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA2IO01
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TUA4CO03	Loading of Wakefields in a Plasma Accelerator Section Driven by a Self-Modulated Proton Beam	ion, plasma, simulation, proton	457
	V.K.B. Olsen, E. Adli University of Oslo, Oslo, Norway P. Muggli MPI-P, München, Germany J. Vieira Instituto Superior Tecnico, Lisbon, Portugal
	Using parameters from the AWAKE project and particle-in-cell simulations we investigate beam loading of a plasma wake driven by a self-modulated proton beam. Addressing the case of injection of an electron witness bunch after the drive beam has already experienced self-modulation in a previous plasma, we optimise witness bunch parameters of size, charge and injection phase to maximise energy gain and minimise relative energy spread and emittance of the accelerated bunch.
	Slides TUA4CO03 [3.103 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA4CO03
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WEA1IO02	Computation of Electromagnetic Fields Generated by Relativistic Beams in Complicated Structures	ion, simulation, electromagnetic-fields, vacuum	642
	I. Zagorodnov DESY, Hamburg, Germany
	We discuss recent developments of numerical methods for computation of wakefields excited by short bunches in accelerators. They include a low-dispersive computational algorithm, conformal approximation of the boundaries, surface conductivity, and indirect wake potential integration. The implementation of these methods in the electromagnetic code ECHO for 2D and 3D problems are presented with a special emphasis on a new ECHO2D code for fast calculations of wakefields in rectangular geometries. Several examples of application of the code to calculation of wakefields for the European Free Electron Laser project and in the Linac Coherent Light Source (LCLS) project are considered.
	Slides WEA1IO02 [4.461 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA1IO02
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WEPOA01	Effect of Proton Bunch Parameter Variation on AWAKE	ion, injection, plasma, electron	684
	N. Savard University of Victoria, Victoria BC, Canada P. Muggli MPI, Muenchen, Germany J. Vieira IPFN, Lisbon, Portugal
	In AWAKE, long proton bunches propagate through a plasma, generating wakefields through the self-modulation instability (SMI). The phase velocity of these wakefields changes during the first 4 m of propagation and growth of the SMI, after which it stabilizes at the proton bunch velocity. This means that the ideal injection point for electrons to be accelerated is after 4 m into the plasma. Using the PIC code OSIRIS, we study how small changes in the initial proton bunch parameters (such as charge, radial and longitudinal bunch length, etc) to be expected in the experiment affect the phase velocity of the wakefields, primarily by looking at the difference in the phase of the wakefields at the point of injection (along the bunch and along the plasma) when changing these parameters by a small amount (±5%). We also look for the region of optimal acceleration/focusing for electron injection. Ultimately, it is found that small changes in the initial proton bunch parameters are not expected to significantly impact electron injection experiments in the future.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA01
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WEPOA09	Proton Beam Defocusing as a Result of Self-Modulation in Plasma	proton, ion, plasma, focusing	707
	M. Turner, E. Gschwendtner, A.V. Petrenko CERN, Geneva, Switzerland K.V. Lotov, A. Sosedkin Budker INP & NSU, Novosibirsk, Russia
	Funding: CERN The AWAKE experiment will use a 400 GeV/c proton beam with a longitudinal bunch length of sigmq_z = 12 cm to create and sustain GV/m plasma wakefields over 10 meters. A 12 cm long bunch can only drive strong wakefields in a plasma with n_pe = 7 x 10¹⁴ electrons/cm³ after the self-modulation instability (SMI) developed and microbunches formed, spaced at the plasma wavelength. The fields present during SMI focus and defocus the protons in the transverse plane. We show that by inserting two imaging screens downstream the plasma, we can measure the maximum defocusing angle of the defocused protons for plasma densities above n_pe = 5 x10¹⁴ electrons/cm³. Measuring maximum defocusing angles around 1 mrad indirectly proves that SMI developed successfully and that GV/m plasma wakefields were created. In this paper we present numerical studies on how and when the wakefields defocus protons in plasma, the expected measurement results of the two screen diagnostics and the physics we can deduce from it.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA09
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WEPOA13	RF Design and Simulation of a Non-Periodic Lattice Photonic Band Gap (PBG) Accelerating Structure	ion, lattice, cavity, photon	716
	N. Zhou, A. Nassiri ANL, Argonne, Illinois, USA
	Photonic Band Gap (PBG) structures (metallic and or dielectric) have been proposed for accelerators. These structures act like a filter, allowing RF field at some frequencies to be transmitted through, while rejecting RF fields in some (unwanted) frequency range. Additionally PBG structures are used to support selective field patterns (modes) in a resonator or waveguide. In this paper, we will report on the RF design and simulation results of an X-band PBG structure, including lattice optimization, to improve RF performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA13
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WEPOA33	Novel Metallic Structures for Wakefield Acceleration	ion, cavity, acceleration, electron	762
	X.Y. Lu, M.A. Shapiro, R.J. Temkin MIT/PSFC, Cambridge, Massachusetts, USA
	Funding: US DOE, Office of High Energy Physics Three novel ideas for wakefield acceleration (WFA) of electrons with metallic periodic subwavelength structures will be presented. The first idea is a deep corrugation structure for collinear WFA. A design for the Argonne Wakefield Accelerator is shown. An analytical model is developed and it agrees with the CST wakefield solver. A scaling study has been performed, and ways to increase the gradient will be discussed. The deep corrugation structure can generate a higher gradient than a dielectric tube with the same beam aperture when excited by the same bunch. The second idea is an elliptical structure for two-beam acceleration (TBA). The unit cell is an elliptical cavity, and the drive beam hole and the witness beam hole are located around the two focal points. The TBA process has been calculated and will be presented. The third idea is a metamaterial ‘wagon wheel' structure for a power extractor design. The fundamental mode is a TM mode with a negative group velocity. A power extractor at 11.7 GHz based on the structure can reach a GW power level when a train of 40 nC bunches with 1.3 GHz rep rate are sent in.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA33
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WEPOA51	Update on Photonic Band Gap Accelerating Structure Experiment	ion, experiment, higher-order-mode, photon	807
	J. Upadhyay, E.I. Simakov LANL, Los Alamos, New Mexico, USA
	Photonic band gap (PBG) structures have great potential in filtering higher order modes (HOMs) without perturbing the fundamental mode and in suppressing the wakefields. An efficient PBG structure would help a lot in terms of beam quality for high beam current future free-electron lasers (FEL). An improved design of X-band normal conducting PBG accelerating structure with elliptical rods will be presented. A comparison of cavity parameters between cylindrical and elliptical shape rod PBG structures will be shown. This new optimized PBG structure would be fabricated and tested at Argonne Wakefield Accelerator (AWA) test facility. The status of the test will be reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA51
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WEPOB19	Summary of Cs2te Photocathode Performance and Improvements in the High-Gradient, High-Charge AWA Drive Gun	cathode, ion, gun, operation	934
	E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, C.-J. Jing, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford ANL, Argonne, Illinois, USA S.P. Antipov, C.-J. Jing, J.Q. Qiu Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The AWA L-band, high-charge photoinjector for the 70 MeV drive beamline has been operating for almost 3 years at the Argonne Wakefield Accelerator (AWA) facility. at Argonne National Laboratory (ANL). The gun operates at high-field (85 MV/m peak field on the cathode) and has a high quantum efficiency (QE) Cesium telluride photocathode with a large area (30 mm diameter). It produces high-charge, short pulse, single bunches (Q > 100 nC) as well as long bunch-trains (Q > 600 nC) for wakefield experiments (high peak current). During the first two years of operation, photocathode performance was evaluated and areas of improvement were identified. After study, consideration and consultation, steps were taken to improve the performance of the photocathode. So far, in total, three photocathodes have been fabricated on-site, installed and operated in the gun. Improvements made to the photocathode plug, vacuum system, and gun operation are detailed. The results include vastly improved conditioning times, better cathode performance, and QE above 4% for over 11 months.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB19
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THPOA08	Transformer Ratio Enhancement Experiment Based on Emittance Exchanger in Argonne Wakefield Accelerator	ion, experiment, GUI, emittance	1115
	Q. Gao, H.B. Chen, J. Shi TUB, Beijing, People's Republic of China S.P. Antipov Euclid Beamlabs LLC, Bolingbrook, USA M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski ANL, Argonne, Illinois, USA C.-J. Jing Euclid TechLabs, LLC, Solon, Ohio, USA
	The transformer ratio is an important figure of merit in collinear wakefield acceleration, it indicates the efficiency of energy transferring from drive bunch to witness bunch. Higher transformer ratio will significantly reduce the length of accelerator thus reducing the cost of accelerator construction. However, for the gaussian bunch, this ratio has its limit of 2. To obtain higher transformer ratio, one possible method is to tailor the beam current profile to specific shapes. One method of beam shaping is based on emittance exchange, which has been demonstrated at the Argonne Wakefield Accelerator. Its principle is to tailor the beam transversely using a mask then exchange the beam's transverse profile and longitudinal profile. In this paper, we describe our efforts to optimize the beamline and mask in order to generate a triangular beam with quadratic head, which has a transformer ratio of 6.4. We also present our design of a dielectric slab based accelerating structure to measure the transformer ratio. Finally, we discuss an experiment for this high transformer ratio at Argonne Wakefield Accelerator Laboratory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA08
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THPOA18	Simulating Batch-on-Batch Slip-Stacking in the Fermilab Recycler Using a New Multiple Interacting Bunch Capability in Synergia	ion, simulation, space-charge, collective-effects	1135
	E.G. Stern, R. Ainsworth, J.F. Amundson, Q. Lu Fermilab, Batavia, Illinois, USA
	Funding: U.S. Department of Energy, contract DE-AC02-07CH11359 The Recycler is an 8 GeV/c proton storage ring at Fermilab. To achieve the 700 MW beam power goals for the NOvA neutrino oscillation experiment, the Recycler accumulates 12 batches of 80-bunch trains from the Booster using slip-stacking. One set of bunch trains are injected into the ring and decelerated, then a second set is injected at the nominal momentum. The trains slip past each other longitudinally due to their momenta difference. We have recently extended the multi-bunch portion of the Synergia beam simulation program to allow co-propagation of bunch trains at different momenta. In doing so, we have expanded the applicability of the massively parallel multi-bunch physics portion of Synergia to include new categories of bunch-bunch interactions. We present results from our first application of these capabilities to batch-on-batch slip stacking in the Recycler.
	Poster THPOA18 [2.144 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA18
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Paper

Title

Other Keywords

Page

MOPOB57

Wakefield Excitation in Power Extraction Cavity of Co-Linear X-Band Energy Booster in Time Domain With ACE3P

ion, cavity, impedance, extraction

195

T. Sipahi, S. Biedron, S.V. Milton
CSU, Fort Collins, Colorado, USA

We provide the general concept and the design details of our proposed Co-linear X-band Energy Booster (CXEB). Here, using the time domain solver T3P of the ACE3P Suite we provide the single bunch and multiple bunch wakefield excitation mechanism for the power build up when using a symmetric Gaussian bunch distribution in our traveling wave (TW) X-band power extraction cavity (PEC). Finally, we determine the achievable X-band power at the end of the PEC structure.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB57

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TUA2IO01

AWAKE - A Proton Driven Plasma Wakefield Acceleration Experiment at CERN

ion, plasma, proton, electron

266

A. Caldwell
MPI-P, München, Germany

It is the aim of the AWAKE project at CERN to demonstrate the acceleration of electrons in the wake created by a proton beam passing through plasma. The proton beam will be modulated as a result of the transverse two-stream instability into a series ofμbunches that will then drive strong wakefields. The wakefields will then be used to accelerate electrons with GV/m strength fields. The AWAKE experiment is currently being commissioned and first data taking is expected this year. The status of the experimental program is described as well as first thoughts on future steps.

Slides TUA2IO01 [24.428 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA2IO01

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TUA4CO03

Loading of Wakefields in a Plasma Accelerator Section Driven by a Self-Modulated Proton Beam

ion, plasma, simulation, proton

457

V.K.B. Olsen, E. Adli
University of Oslo, Oslo, Norway
P. Muggli
MPI-P, München, Germany
J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

Using parameters from the AWAKE project and particle-in-cell simulations we investigate beam loading of a plasma wake driven by a self-modulated proton beam. Addressing the case of injection of an electron witness bunch after the drive beam has already experienced self-modulation in a previous plasma, we optimise witness bunch parameters of size, charge and injection phase to maximise energy gain and minimise relative energy spread and emittance of the accelerated bunch.

Slides TUA4CO03 [3.103 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUA4CO03

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WEA1IO02

Computation of Electromagnetic Fields Generated by Relativistic Beams in Complicated Structures

ion, simulation, electromagnetic-fields, vacuum

642

I. Zagorodnov
DESY, Hamburg, Germany

We discuss recent developments of numerical methods for computation of wakefields excited by short bunches in accelerators. They include a low-dispersive computational algorithm, conformal approximation of the boundaries, surface conductivity, and indirect wake potential integration. The implementation of these methods in the electromagnetic code ECHO for 2D and 3D problems are presented with a special emphasis on a new ECHO2D code for fast calculations of wakefields in rectangular geometries. Several examples of application of the code to calculation of wakefields for the European Free Electron Laser project and in the Linac Coherent Light Source (LCLS) project are considered.

Slides WEA1IO02 [4.461 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA1IO02

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WEPOA01

Effect of Proton Bunch Parameter Variation on AWAKE

ion, injection, plasma, electron

684

N. Savard
University of Victoria, Victoria BC, Canada
P. Muggli
MPI, Muenchen, Germany
J. Vieira
IPFN, Lisbon, Portugal

In AWAKE, long proton bunches propagate through a plasma, generating wakefields through the self-modulation instability (SMI). The phase velocity of these wakefields changes during the first 4 m of propagation and growth of the SMI, after which it stabilizes at the proton bunch velocity. This means that the ideal injection point for electrons to be accelerated is after 4 m into the plasma. Using the PIC code OSIRIS, we study how small changes in the initial proton bunch parameters (such as charge, radial and longitudinal bunch length, etc) to be expected in the experiment affect the phase velocity of the wakefields, primarily by looking at the difference in the phase of the wakefields at the point of injection (along the bunch and along the plasma) when changing these parameters by a small amount (±5%). We also look for the region of optimal acceleration/focusing for electron injection. Ultimately, it is found that small changes in the initial proton bunch parameters are not expected to significantly impact electron injection experiments in the future.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA01

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WEPOA09

Proton Beam Defocusing as a Result of Self-Modulation in Plasma

proton, ion, plasma, focusing

707

M. Turner, E. Gschwendtner, A.V. Petrenko
CERN, Geneva, Switzerland
K.V. Lotov, A. Sosedkin
Budker INP & NSU, Novosibirsk, Russia

Funding: CERN
The AWAKE experiment will use a 400 GeV/c proton beam with a longitudinal bunch length of sigmq_z = 12 cm to create and sustain GV/m plasma wakefields over 10 meters. A 12 cm long bunch can only drive strong wakefields in a plasma with n_pe = 7 x 10¹⁴ electrons/cm³ after the self-modulation instability (SMI) developed and microbunches formed, spaced at the plasma wavelength. The fields present during SMI focus and defocus the protons in the transverse plane. We show that by inserting two imaging screens downstream the plasma, we can measure the maximum defocusing angle of the defocused protons for plasma densities above n_pe = 5 x10¹⁴ electrons/cm³. Measuring maximum defocusing angles around 1 mrad indirectly proves that SMI developed successfully and that GV/m plasma wakefields were created. In this paper we present numerical studies on how and when the wakefields defocus protons in plasma, the expected measurement results of the two screen diagnostics and the physics we can deduce from it.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA09

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

WEPOA13

RF Design and Simulation of a Non-Periodic Lattice Photonic Band Gap (PBG) Accelerating Structure

ion, lattice, cavity, photon

716

N. Zhou, A. Nassiri
ANL, Argonne, Illinois, USA

Photonic Band Gap (PBG) structures (metallic and or dielectric) have been proposed for accelerators. These structures act like a filter, allowing RF field at some frequencies to be transmitted through, while rejecting RF fields in some (unwanted) frequency range. Additionally PBG structures are used to support selective field patterns (modes) in a resonator or waveguide. In this paper, we will report on the RF design and simulation results of an X-band PBG structure, including lattice optimization, to improve RF performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA13

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WEPOA33

Novel Metallic Structures for Wakefield Acceleration

ion, cavity, acceleration, electron

762

X.Y. Lu, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

Funding: US DOE, Office of High Energy Physics
Three novel ideas for wakefield acceleration (WFA) of electrons with metallic periodic subwavelength structures will be presented. The first idea is a deep corrugation structure for collinear WFA. A design for the Argonne Wakefield Accelerator is shown. An analytical model is developed and it agrees with the CST wakefield solver. A scaling study has been performed, and ways to increase the gradient will be discussed. The deep corrugation structure can generate a higher gradient than a dielectric tube with the same beam aperture when excited by the same bunch. The second idea is an elliptical structure for two-beam acceleration (TBA). The unit cell is an elliptical cavity, and the drive beam hole and the witness beam hole are located around the two focal points. The TBA process has been calculated and will be presented. The third idea is a metamaterial ‘wagon wheel' structure for a power extractor design. The fundamental mode is a TM mode with a negative group velocity. A power extractor at 11.7 GHz based on the structure can reach a GW power level when a train of 40 nC bunches with 1.3 GHz rep rate are sent in.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA33

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

WEPOA51

Update on Photonic Band Gap Accelerating Structure Experiment

ion, experiment, higher-order-mode, photon

807

J. Upadhyay, E.I. Simakov
LANL, Los Alamos, New Mexico, USA

Photonic band gap (PBG) structures have great potential in filtering higher order modes (HOMs) without perturbing the fundamental mode and in suppressing the wakefields. An efficient PBG structure would help a lot in terms of beam quality for high beam current future free-electron lasers (FEL). An improved design of X-band normal conducting PBG accelerating structure with elliptical rods will be presented. A comparison of cavity parameters between cylindrical and elliptical shape rod PBG structures will be shown. This new optimized PBG structure would be fabricated and tested at Argonne Wakefield Accelerator (AWA) test facility. The status of the test will be reported.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOA51

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

WEPOB19

Summary of Cs2te Photocathode Performance and Improvements in the High-Gradient, High-Charge AWA Drive Gun

cathode, ion, gun, operation

934

E.E. Wisniewski, S.P. Antipov, M.E. Conde, D.S. Doran, W. Gai, C.-J. Jing, W. Liu, J.G. Power, J.Q. Qiu, C. Whiteford
ANL, Argonne, Illinois, USA
S.P. Antipov, C.-J. Jing, J.Q. Qiu
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Argonne, a U.S.A. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
The AWA L-band, high-charge photoinjector for the 70 MeV drive beamline has been operating for almost 3 years at the Argonne Wakefield Accelerator (AWA) facility. at Argonne National Laboratory (ANL). The gun operates at high-field (85 MV/m peak field on the cathode) and has a high quantum efficiency (QE) Cesium telluride photocathode with a large area (30 mm diameter). It produces high-charge, short pulse, single bunches (Q > 100 nC) as well as long bunch-trains (Q > 600 nC) for wakefield experiments (high peak current). During the first two years of operation, photocathode performance was evaluated and areas of improvement were identified. After study, consideration and consultation, steps were taken to improve the performance of the photocathode. So far, in total, three photocathodes have been fabricated on-site, installed and operated in the gun. Improvements made to the photocathode plug, vacuum system, and gun operation are detailed. The results include vastly improved conditioning times, better cathode performance, and QE above 4% for over 11 months.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB19

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THPOA08

Transformer Ratio Enhancement Experiment Based on Emittance Exchanger in Argonne Wakefield Accelerator

ion, experiment, GUI, emittance

1115

Q. Gao, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China
S.P. Antipov
Euclid Beamlabs LLC, Bolingbrook, USA
M.E. Conde, D.S. Doran, W. Gai, W. Liu, J.G. Power, C. Whiteford, E.E. Wisniewski
ANL, Argonne, Illinois, USA
C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA

The transformer ratio is an important figure of merit in collinear wakefield acceleration, it indicates the efficiency of energy transferring from drive bunch to witness bunch. Higher transformer ratio will significantly reduce the length of accelerator thus reducing the cost of accelerator construction. However, for the gaussian bunch, this ratio has its limit of 2. To obtain higher transformer ratio, one possible method is to tailor the beam current profile to specific shapes. One method of beam shaping is based on emittance exchange, which has been demonstrated at the Argonne Wakefield Accelerator. Its principle is to tailor the beam transversely using a mask then exchange the beam's transverse profile and longitudinal profile. In this paper, we describe our efforts to optimize the beamline and mask in order to generate a triangular beam with quadratic head, which has a transformer ratio of 6.4. We also present our design of a dielectric slab based accelerating structure to measure the transformer ratio. Finally, we discuss an experiment for this high transformer ratio at Argonne Wakefield Accelerator Laboratory.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA08

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THPOA18

Simulating Batch-on-Batch Slip-Stacking in the Fermilab Recycler Using a New Multiple Interacting Bunch Capability in Synergia

ion, simulation, space-charge, collective-effects

1135

E.G. Stern, R. Ainsworth, J.F. Amundson, Q. Lu
Fermilab, Batavia, Illinois, USA

Funding: U.S. Department of Energy, contract DE-AC02-07CH11359
The Recycler is an 8 GeV/c proton storage ring at Fermilab. To achieve the 700 MW beam power goals for the NOvA neutrino oscillation experiment, the Recycler accumulates 12 batches of 80-bunch trains from the Booster using slip-stacking. One set of bunch trains are injected into the ring and decelerated, then a second set is injected at the nominal momentum. The trains slip past each other longitudinally due to their momenta difference. We have recently extended the multi-bunch portion of the Synergia beam simulation program to allow co-propagation of bunch trains at different momenta. In doing so, we have expanded the applicability of the massively parallel multi-bunch physics portion of Synergia to include new categories of bunch-bunch interactions. We present results from our first application of these capabilities to batch-on-batch slip stacking in the Recycler.

Poster THPOA18 [2.144 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA18

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