IPAC2022 - Classification: MC5: Beam Dynamics and EM Fields / D09: Emittance manipulation, Bunch Compression and Cooling

Paper	Title	Page
WEOZSP1	Longitudinal Bunch Shaping Using an X-Band Transverse Deflecting Cavity Powered by Wakefield Power Extractor at Argonne Wakefield Accelerator Facility	1655
	S.Y. Kim, G. Chen, D.S. Doran, W. Liu, J.G. Power, E.E. Wisniewski ANL, Lemont, Illinois, USA A. Bibian, C.-J. Jing, E.W. Knight, S.V. Kuzikov Euclid TechLabs, Solon, Ohio, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: This project is supported under DoE SBIR Phase I Grant No. DE-SC0021733. This work is also supported by Department of Energy, Office of Science, under contract No. DEAC02-06CH11357. Longitudinal bunch shaping using transverse deflecting cavities (TDC) was recently proposed. This configuration is well suited for shaping the current profile of high-charge bunches since it does not use dipole magnets, and therefore, is not prone to deleterious effects arising from coherent synchrotron radiation. An intercepting mask located downstream of the first TDC, which introduce a spatiotemporal correlation, transversely shape the beam. Downstream of the second TDC, upon removal of the cross-plane correlation, the bunch is temporally shaped. In this paper, we investigate longitudinal bunch shaping with an X-band TDC powered by an X-band, short-pulse wakefield Power Extraction and Transfer Structure (PETS), where the wakefield from the drive beam propagating through the PETS is the power source. We describe the RF designs of the X-band TDC and the configuration of the overall shaping system. Finally, we explore via beam-dynamics simulations the performances of the proposed shaper and its possible application to various bunch shapes relevant to beam-driven acceleration and coherent radiation generation. Gwanghui Ha et al., Phys. Rev. Accel. Beams 23, 072803, 2020
	Slides WEOZSP1 [6.235 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP1
About •	Received ※ 14 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022
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WEPOPT025	Flat Beam Generation with the Phase Space Rotation Technique at KEK-STF	1897
	M. Kuriki, Z.J. Liptak HU/AdSM, Higashi-Hiroshima, Japan S. Aramoto Hiroshima University, Higashi-Hiroshima, Japan H. Hayano, X.J. Jin, Y. Seimiya, N. Yamamoto, Y. Yamamoto KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan K. Sakaue The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan M. Washio RISE, Tokyo, Japan
	Flat beam generation from angular momentum dominated beam with a phase-space rotation technique is an unique method to manipulate the phase-space distribution of beam. As an application, the asymmetric emittance beam generation for linear colliders is considered to compensate the Beamstrahlung effect at Interaction point. By using this technique, the asymmetric beam can be generated directly with the injector, instead of radiation damping with a huge damping ring. We present the result of a proof-of-principle experiment at KEK-STF.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT025
About •	Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022
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WEPOTK060	Prospects of Ultrafast Electron Diffraction Experiments at Sealab	2201
SUSPMF076	use link to see paper's listing under its alternate paper code
	B. Alberdi-Esuain, J.-G. Hwang, T. Kamps, A. Neumann, J. Völker HZB, Berlin, Germany T. Kamps HU Berlin, Berlin, Germany
	Ultrafast Electron Diffraction (UED) is a pump-probe experimental technique that aims to image the structural changes that happen in a target structure due to photo-excitation. Development of MeV UED capabilities is one of the main objectives at Sealab, a superconducting RF accelerator facility being commissioned in Helmholtz-Zentrum Berlin. In order to perform UED experiments, the optimization of temporal resolution is of the utmost importance. The composition of the SRF Photoinjector, currently the main beam-line in Sealab, offers superb flexibility to manipulate the longitudinal phase-space of the electron bunch. At the same time, the CW operation of the accelerator provides an enhanced beam stability compared to warm guns, together with MHz repetition rates. This work aims to show the capacity of the SRF Photoinjector in Sealab to reach the required temporal resolution and explain the development and current status of the necessary tools to perform UED experiments at the facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK060
About •	Received ※ 08 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 03 July 2022
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WEPOMS018	Minimum Emittance Growth during RF-Phase Slip	2276
	S.R. Koscielniak TRIUMF, Vancouver, Canada
	This paper is concerned with finding operations consistent with the absolute minimum emittance growth. The system is an RF bucket containing a bunch of hadrons in a synchrotron; and the operation performed is to sweep the RF phase. As a result, the bunch centroid moves from one value of position and momentum to another. For given start and end points, we shall find the ideal RF phase-slip time-variation that minimizes emittance growth of the bunch
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS018
About •	Received ※ 27 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 25 June 2022
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WEPOMS020	FAIR SIS100 Laser Cooling Pilot Facility	2284
	S. Klammes, T. Kühl, P.J. Spiller, T. Stöhlker, D.F.A. Winters GSI, Darmstadt, Germany M.H. Bussmann, U. Schramm, M. Siebold HZDR, Dresden, Germany M.H. Bussmann CASUS, Görlitz, Germany J. Gumm, B. Langfeld, T. Walther TU Darmstadt, Darmstadt, Germany V. Hannen, K. Ueberholz Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany X. Ma, W.Q. Wen IMP/CAS, Lanzhou, People’s Republic of China U. Schramm TU Dresden, Dresden, Germany T. Stöhlker HIJ, Jena, Germany T. Stöhlker IOQ, Jena, Germany T. Walther HFHF, Frankfurt am Main, Germany
	We present new (preliminary) results from a recent (May 2021) beam experiment for laser cooling of bunched relativistic carbon ion beams at the ESR of the GSI Helmholtz Centre in Darmstadt, Germany. We were able to use the new pulsed UV laser system from the TU Darmstadt, which has a very high repetition rate, a variable pulse duration and high UV power (up to 250 mW @ 257 nm). Using this laser, we have - for the first time - demonstrated laser cooling of bunched relativistic ion beams for different laser pulse durations (166-740 ps) at a ~10 MHz repetition rate. In addition, we could use the moveable in-vacuo (X)UV detection system from Münster University to study the fluorescence from the laser-excited ions. Finally, we have observed clear effects in the amount of detected fluorescence from the ions using our new ion bunch - laser pulse timing scheme. These studies are also highly relevant for the SIS100 laser cooling pilot facility, which is currently being realized at FAIR.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS020
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 13 June 2022
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WEPOMS021	Entropy Production and Emittance Growth Due to the Imperfection in Long Periodical Acceleration Chains	2286
	M. Droba, O. Meusel, H. Podlech, S. Reimann IAP, Frankfurt am Main, Germany H. Podlech HFHF, Frankfurt am Main, Germany S. Reimann GSI, Darmstadt, Germany
	Contemporary design of efficient linear accelerator is based on ideal periodical structures with an optimi-sation for perfect periodicity. However, practical reali-sation involves random errors in the structure (e.g. position of elements, off-sets, non-linearity of the fields etc.) which make prediction of emittance growth difficult. Error studies helps to understand critical points, but they are normally used at the end of the design process. The concept of beam entropy in very simple approximation (assumption of Ornstein-Uhlenbeck model) is used to evaluate emittance growth in perfect periodical chains. The analysis will be performed and differences in modern designs on some examples discussed. Focus will be laid on linac designs with short acceleration structures (RF-phase settings versus position error) and external transversal focusing magnets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS021
About •	Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 23 June 2022
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WEPOMS022	Detailed Analysis of Transverse Emittance of the FLUTE Electron Bunch	2289
	T. Schmelzer, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski KIT, Karlsruhe, Germany
	The compact and versatile linear accelerator-based test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) is operated at KIT. Its primary goal is to serve as a platform for a variety of accelerator R\&D studies like the generation of strong ultra-short terahertz pulses. The amplitude of the generated coherent THz pulses is proportional to the square number of particles in the bunch. With the transverse emittance a measure for the transverse particle density can be determined. It is therefore a vital parameter in the optimization for operation. In a systematic study, the transverse emittance of the electron beam was measured in the FLUTE injector. A detailed analysis considers different influences such as the bunch charge and compares this with particle tracking simulations carried out with ASTRA. In this contribution, the key findings of this analysis are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS022
About •	Received ※ 08 June 2022 — Revised ※ 23 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 28 June 2022
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WEPOMS024	Present Status of the Injector at the Compact ERL at KEK	2296
	O.A. Tanaka, T. Miyajima, T. Tanikawa KEK, Ibaraki, Japan
	The Compact ERL at KEK is a test accelerator to develop ERL technologies and their possible applications. The first target of injector operation to demonstrate IR-FEL was to generate high bunch charge electron beams with low longitudinal emittance and short bunch length. In 2020, the injector was operated with the bunch charge of 60 pC, the DC gun voltage of 480 kV, the injector energy of 5 MeV and the bunch length of 2 ps rms, and the required beam quality for the IR-FEL has been achieved for a single-pass operation mode. The next target is to demonstrate IR-FEL generation for recirculation mode. The injector energy is decreased to 3.5 MeV due to a limitation of the energy ratio between injection and recirculation beams. Moreover, the DC gun voltage decreases to 390 kV due to the troubles of the DC gun. Therefore, control of the space charge effect is more important to design and optimize the beam transport condition of the injector. In this report, a strategy of the injector optimization together with its realization results and future prospects are summarized.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS024
About •	Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 19 June 2022 — Issue date ※ 21 June 2022
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WEPOMS025	Injector Design Towards ERL-Based EUV-FEL for Lithography	2299
	O.A. Tanaka, T. Miyajima, N. Nakamura, T. Tanikawa KEK, Ibaraki, Japan
	A high-power EUV light source using ERL-based FEL can supply multiple semiconductor exposure de-vices. There are some requirements in the whole and its injector, in particular, and their examination and necessary development are being carried out. The requirement for the injector was to generate high bunch charge beams at a high-repetition rate. In this regard, a space charge effect should be treated carefully in the design of the injector. For FEL operation, not only short bunch length and small transverse emittance but also small longitudinal emittance are required. By using a multi-objective genetic algorithm, we are minimizing them at the exit of the injector to investigate the injector performance and its effect on the FEL generation. In this study, we describe the injector optimization strategies and possible options suited for the ERL-based EUV-FEL.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS025
About •	Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022
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WEPOMS028	Electron Beam Shaping Techniques Using Optical Stochastic Cooling	2303
	A.J. Dick, P. Piot Northern Illinois University, DeKalb, Illinois, USA P. Piot ANL, Lemont, Illinois, USA
	Optical Stochastic Cooling (OSC) has demonstrated its ability to reduce the three-dimensional phase-space emittance of an electron beam by applying a small corrective kick to the beam each turn. By modifying the shape and timing of these kicks we can produce specific longitudinal beam distributions. Two methods are introduced; single-pulse modulation, where the longitudinal profile of the OSC pulse is amplified by some function, as well as multiple-turn modulation, where the overall strength or phase is varied depending on the synchrotron oscillation phase. The shaping techniques are demonstrated using a model of OSC developed in the ELEGANT particle-tracking code program.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS028
About •	Received ※ 13 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 21 June 2022 — Issue date ※ 04 July 2022
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WEPOMS029	Modeling of the Optical Stochastic Cooling at the IOTA Storage Ring Using ELEGANT	2307
	A.J. Dick, P. Piot Northern Illinois University, DeKalb, Illinois, USA J.D. Jarvis Fermilab, Batavia, Illinois, USA P. Piot ANL, Lemont, Illinois, USA
	In support of the Optical Stochastic Cooling (OSC) experiment at IOTA, we implemented a high-fidelity model of OSC in ELEGANT. The element is generalizable to any OSC experiment and captures three main behaviors; (i) the longitudinal time of flight OSC, (ii) the effects between the transverse motion of particles in the beam and the transverse distribution of undulator radiation, and (iii) the incoherent contributions of neighboring particles. Together these produce a highly accurate model of OSC and were benchmarked using the results from the IOTA OSC experiment.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS029
About •	Received ※ 14 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 05 July 2022 — Issue date ※ 06 July 2022
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WEPOMS030	A Path-Length Stability Experiment for Optical Stochastic Cooling at the Cornell Electron Storage Ring	2311
SUSPMF077	use link to see paper's listing under its alternate paper code
	S.J. Levenson, M.B. Andorf, I.V. Bazarov, V. Khachatryan, J.M. Maxson, D.L. Rubin, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams and NYSTAR award C150153. To achieve sufficient particle delay with respect to the optical path in order to enable high gain amplification, the design of the Optical Stochastic Cooling (OSC) experiment in the Cornell Electron Storage Ring (CESR) places the pickup (PU) and kicker (KU) undulators approximately 80 m apart. The arrival times at the KU of particles and the light they produce in the PU must be synchronized to an accuracy of less than an optical wavelength, which for this experiment is 780 nm. To test this synchronization, a planned demonstration of the stability of the bypass in CESR is presented where, in lieu of undulators, an interference pattern formed with radiation from two dipoles flanking the bypass is used. In addition to demonstrating stability, the fringe visibility of the pattern is related to the cooling ranges, a critical parameter needed for OSC. We present progress on this stabilization experiment including the design of a second-order isochronous bypass, as well as optimizations of the Dynamic Aperture (DA) and injection efficiency.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS030
About •	Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 26 June 2022
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WEPOMS031	Light Path Construction for an Optical Stochastic Cooling Stability Test at the Cornell Electron Storage Ring	2315
	S.J. Levenson, M.B. Andorf, I.V. Bazarov, D.C. Burke, J.M. Maxson, D.L. Rubin, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams and NYSTAR award C150153. An experiment at the Cornell Electron Storage Ring (CESR) to test the optical path-length stability of a bypass suitable for Optical Stochastic Cooling (OSC) is being pursued. The approximately 80 m light path for this experiment has been assembled, and synchrotron light has been successfully propagated from both sources. A feedback system based on an Electro-Optic Modulator (EOM) to correct the path-error accumulated in both the light and particle path has been table-top tested. We present on the design and construction of the light optics for the OSC stability experiment at CESR.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS031
About •	Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 21 June 2022 — Issue date ※ 03 July 2022
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WEPOMS032	Simulations of Coherent Electron Cooling with Orbit Deviation	2319
	J. Ma, V. Litvinenko, G. Wang BNL, Upton, New York, USA V. Litvinenko Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy. Coherent electron cooling (CeC) is a novel technique for rapidly cooling high-energy, high-intensity hadron beam. Plasma cascade amplifier (PCA) has been proposed for the CeC experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Cooling performance of PCA based CeC has been predicted in 3D start-to-end CeC simulations using code SPACE. The dependence of the PCA gain and the cooling rate on the electron beam’s orbit deviation has been explored in the simulation studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS032
About •	Received ※ 16 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 29 June 2022
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Paper

Title

Page

Longitudinal Bunch Shaping Using an X-Band Transverse Deflecting Cavity Powered by Wakefield Power Extractor at Argonne Wakefield Accelerator Facility

1655

S.Y. Kim, G. Chen, D.S. Doran, W. Liu, J.G. Power, E.E. Wisniewski
ANL, Lemont, Illinois, USA
A. Bibian, C.-J. Jing, E.W. Knight, S.V. Kuzikov
Euclid TechLabs, Solon, Ohio, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: This project is supported under DoE SBIR Phase I Grant No. DE-SC0021733. This work is also supported by Department of Energy, Office of Science, under contract No. DEAC02-06CH11357.
Longitudinal bunch shaping using transverse deflecting cavities (TDC) was recently proposed*. This configuration is well suited for shaping the current profile of high-charge bunches since it does not use dipole magnets, and therefore, is not prone to deleterious effects arising from coherent synchrotron radiation. An intercepting mask located downstream of the first TDC, which introduce a spatiotemporal correlation, transversely shape the beam. Downstream of the second TDC, upon removal of the cross-plane correlation, the bunch is temporally shaped. In this paper, we investigate longitudinal bunch shaping with an X-band TDC powered by an X-band, short-pulse wakefield Power Extraction and Transfer Structure (PETS), where the wakefield from the drive beam propagating through the PETS is the power source. We describe the RF designs of the X-band TDC and the configuration of the overall shaping system. Finally, we explore via beam-dynamics simulations the performances of the proposed shaper and its possible application to various bunch shapes relevant to beam-driven acceleration and coherent radiation generation.
*Gwanghui Ha et al., Phys. Rev. Accel. Beams 23, 072803, 2020

Slides WEOZSP1 [6.235 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP1

About •

Received ※ 14 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022

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WEPOPT025

Flat Beam Generation with the Phase Space Rotation Technique at KEK-STF

1897

M. Kuriki, Z.J. Liptak
HU/AdSM, Higashi-Hiroshima, Japan
S. Aramoto
Hiroshima University, Higashi-Hiroshima, Japan
H. Hayano, X.J. Jin, Y. Seimiya, N. Yamamoto, Y. Yamamoto
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
K. Sakaue
The University of Tokyo, Graduate School of Engineering, Bunkyo, Japan
M. Washio
RISE, Tokyo, Japan

Flat beam generation from angular momentum dominated beam with a phase-space rotation technique is an unique method to manipulate the phase-space distribution of beam. As an application, the asymmetric emittance beam generation for linear colliders is considered to compensate the Beamstrahlung effect at Interaction point. By using this technique, the asymmetric beam can be generated directly with the injector, instead of radiation damping with a huge damping ring. We present the result of a proof-of-principle experiment at KEK-STF.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT025

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Received ※ 07 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 23 June 2022

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

WEPOTK060

Prospects of Ultrafast Electron Diffraction Experiments at Sealab

2201

SUSPMF076

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

B. Alberdi-Esuain, J.-G. Hwang, T. Kamps, A. Neumann, J. Völker
HZB, Berlin, Germany
T. Kamps
HU Berlin, Berlin, Germany

Ultrafast Electron Diffraction (UED) is a pump-probe experimental technique that aims to image the structural changes that happen in a target structure due to photo-excitation. Development of MeV UED capabilities is one of the main objectives at Sealab, a superconducting RF accelerator facility being commissioned in Helmholtz-Zentrum Berlin. In order to perform UED experiments, the optimization of temporal resolution is of the utmost importance. The composition of the SRF Photoinjector, currently the main beam-line in Sealab, offers superb flexibility to manipulate the longitudinal phase-space of the electron bunch. At the same time, the CW operation of the accelerator provides an enhanced beam stability compared to warm guns, together with MHz repetition rates. This work aims to show the capacity of the SRF Photoinjector in Sealab to reach the required temporal resolution and explain the development and current status of the necessary tools to perform UED experiments at the facility.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK060

About •

Received ※ 08 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 03 July 2022

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WEPOMS018

Minimum Emittance Growth during RF-Phase Slip

2276

S.R. Koscielniak
TRIUMF, Vancouver, Canada

This paper is concerned with finding operations consistent with the absolute minimum emittance growth. The system is an RF bucket containing a bunch of hadrons in a synchrotron; and the operation performed is to sweep the RF phase. As a result, the bunch centroid moves from one value of position and momentum to another. For given start and end points, we shall find the ideal RF phase-slip time-variation that minimizes emittance growth of the bunch

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS018

About •

Received ※ 27 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 12 June 2022 — Issue date ※ 25 June 2022

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WEPOMS020

FAIR SIS100 Laser Cooling Pilot Facility

2284

S. Klammes, T. Kühl, P.J. Spiller, T. Stöhlker, D.F.A. Winters
GSI, Darmstadt, Germany
M.H. Bussmann, U. Schramm, M. Siebold
HZDR, Dresden, Germany
M.H. Bussmann
CASUS, Görlitz, Germany
J. Gumm, B. Langfeld, T. Walther
TU Darmstadt, Darmstadt, Germany
V. Hannen, K. Ueberholz
Westfälische Wilhelms-Universität Münster, Institut für Kernphysik, Münster, Germany
X. Ma, W.Q. Wen
IMP/CAS, Lanzhou, People’s Republic of China
U. Schramm
TU Dresden, Dresden, Germany
T. Stöhlker
HIJ, Jena, Germany
T. Stöhlker
IOQ, Jena, Germany
T. Walther
HFHF, Frankfurt am Main, Germany

We present new (preliminary) results from a recent (May 2021) beam experiment for laser cooling of bunched relativistic carbon ion beams at the ESR of the GSI Helmholtz Centre in Darmstadt, Germany. We were able to use the new pulsed UV laser system from the TU Darmstadt, which has a very high repetition rate, a variable pulse duration and high UV power (up to 250 mW @ 257 nm). Using this laser, we have - for the first time - demonstrated laser cooling of bunched relativistic ion beams for different laser pulse durations (166-740 ps) at a ~10 MHz repetition rate. In addition, we could use the moveable in-vacuo (X)UV detection system from Münster University to study the fluorescence from the laser-excited ions. Finally, we have observed clear effects in the amount of detected fluorescence from the ions using our new ion bunch - laser pulse timing scheme. These studies are also highly relevant for the SIS100 laser cooling pilot facility, which is currently being realized at FAIR.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS020

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 13 June 2022

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WEPOMS021

Entropy Production and Emittance Growth Due to the Imperfection in Long Periodical Acceleration Chains

2286

M. Droba, O. Meusel, H. Podlech, S. Reimann
IAP, Frankfurt am Main, Germany
H. Podlech
HFHF, Frankfurt am Main, Germany
S. Reimann
GSI, Darmstadt, Germany

Contemporary design of efficient linear accelerator is based on ideal periodical structures with an optimi-sation for perfect periodicity. However, practical reali-sation involves random errors in the structure (e.g. position of elements, off-sets, non-linearity of the fields etc.) which make prediction of emittance growth difficult. Error studies helps to understand critical points, but they are normally used at the end of the design process. The concept of beam entropy in very simple approximation (assumption of Ornstein-Uhlenbeck model) is used to evaluate emittance growth in perfect periodical chains. The analysis will be performed and differences in modern designs on some examples discussed. Focus will be laid on linac designs with short acceleration structures (RF-phase settings versus position error) and external transversal focusing magnets.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS021

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Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 23 June 2022

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WEPOMS022

Detailed Analysis of Transverse Emittance of the FLUTE Electron Bunch

2289

T. Schmelzer, E. Bründermann, A.-S. Müller, M.J. Nasse, R. Ruprecht, J. Schäfer, M. Schuh, N.J. Smale, P. Wesolowski
KIT, Karlsruhe, Germany

The compact and versatile linear accelerator-based test facility FLUTE (Ferninfrarot Linac- Und Test-Experiment) is operated at KIT. Its primary goal is to serve as a platform for a variety of accelerator R\&D studies like the generation of strong ultra-short terahertz pulses. The amplitude of the generated coherent THz pulses is proportional to the square number of particles in the bunch. With the transverse emittance a measure for the transverse particle density can be determined. It is therefore a vital parameter in the optimization for operation. In a systematic study, the transverse emittance of the electron beam was measured in the FLUTE injector. A detailed analysis considers different influences such as the bunch charge and compares this with particle tracking simulations carried out with ASTRA. In this contribution, the key findings of this analysis are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS022

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Received ※ 08 June 2022 — Revised ※ 23 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 28 June 2022

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WEPOMS024

Present Status of the Injector at the Compact ERL at KEK

2296

O.A. Tanaka, T. Miyajima, T. Tanikawa
KEK, Ibaraki, Japan

The Compact ERL at KEK is a test accelerator to develop ERL technologies and their possible applications. The first target of injector operation to demonstrate IR-FEL was to generate high bunch charge electron beams with low longitudinal emittance and short bunch length. In 2020, the injector was operated with the bunch charge of 60 pC, the DC gun voltage of 480 kV, the injector energy of 5 MeV and the bunch length of 2 ps rms, and the required beam quality for the IR-FEL has been achieved for a single-pass operation mode. The next target is to demonstrate IR-FEL generation for recirculation mode. The injector energy is decreased to 3.5 MeV due to a limitation of the energy ratio between injection and recirculation beams. Moreover, the DC gun voltage decreases to 390 kV due to the troubles of the DC gun. Therefore, control of the space charge effect is more important to design and optimize the beam transport condition of the injector. In this report, a strategy of the injector optimization together with its realization results and future prospects are summarized.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS024

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Received ※ 08 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 19 June 2022 — Issue date ※ 21 June 2022

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WEPOMS025

Injector Design Towards ERL-Based EUV-FEL for Lithography

2299

O.A. Tanaka, T. Miyajima, N. Nakamura, T. Tanikawa
KEK, Ibaraki, Japan

A high-power EUV light source using ERL-based FEL can supply multiple semiconductor exposure de-vices. There are some requirements in the whole and its injector, in particular, and their examination and necessary development are being carried out. The requirement for the injector was to generate high bunch charge beams at a high-repetition rate. In this regard, a space charge effect should be treated carefully in the design of the injector. For FEL operation, not only short bunch length and small transverse emittance but also small longitudinal emittance are required. By using a multi-objective genetic algorithm, we are minimizing them at the exit of the injector to investigate the injector performance and its effect on the FEL generation. In this study, we describe the injector optimization strategies and possible options suited for the ERL-based EUV-FEL.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS025

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Received ※ 08 June 2022 — Revised ※ 10 June 2022 — Accepted ※ 17 June 2022 — Issue date ※ 17 June 2022

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WEPOMS028

Electron Beam Shaping Techniques Using Optical Stochastic Cooling

2303

A.J. Dick, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
ANL, Lemont, Illinois, USA

Optical Stochastic Cooling (OSC) has demonstrated its ability to reduce the three-dimensional phase-space emittance of an electron beam by applying a small corrective kick to the beam each turn. By modifying the shape and timing of these kicks we can produce specific longitudinal beam distributions. Two methods are introduced; single-pulse modulation, where the longitudinal profile of the OSC pulse is amplified by some function, as well as multiple-turn modulation, where the overall strength or phase is varied depending on the synchrotron oscillation phase. The shaping techniques are demonstrated using a model of OSC developed in the ELEGANT particle-tracking code program.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS028

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Received ※ 13 June 2022 — Revised ※ 14 June 2022 — Accepted ※ 21 June 2022 — Issue date ※ 04 July 2022

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WEPOMS029

Modeling of the Optical Stochastic Cooling at the IOTA Storage Ring Using ELEGANT

2307

A.J. Dick, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J.D. Jarvis
Fermilab, Batavia, Illinois, USA
P. Piot
ANL, Lemont, Illinois, USA

In support of the Optical Stochastic Cooling (OSC) experiment at IOTA, we implemented a high-fidelity model of OSC in ELEGANT. The element is generalizable to any OSC experiment and captures three main behaviors; (i) the longitudinal time of flight OSC, (ii) the effects between the transverse motion of particles in the beam and the transverse distribution of undulator radiation, and (iii) the incoherent contributions of neighboring particles. Together these produce a highly accurate model of OSC and were benchmarked using the results from the IOTA OSC experiment.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS029

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Received ※ 14 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 05 July 2022 — Issue date ※ 06 July 2022

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WEPOMS030

A Path-Length Stability Experiment for Optical Stochastic Cooling at the Cornell Electron Storage Ring

2311

SUSPMF077

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S.J. Levenson, M.B. Andorf, I.V. Bazarov, V. Khachatryan, J.M. Maxson, D.L. Rubin, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams and NYSTAR award C150153.
To achieve sufficient particle delay with respect to the optical path in order to enable high gain amplification, the design of the Optical Stochastic Cooling (OSC) experiment in the Cornell Electron Storage Ring (CESR) places the pickup (PU) and kicker (KU) undulators approximately 80 m apart. The arrival times at the KU of particles and the light they produce in the PU must be synchronized to an accuracy of less than an optical wavelength, which for this experiment is 780 nm. To test this synchronization, a planned demonstration of the stability of the bypass in CESR is presented where, in lieu of undulators, an interference pattern formed with radiation from two dipoles flanking the bypass is used. In addition to demonstrating stability, the fringe visibility of the pattern is related to the cooling ranges, a critical parameter needed for OSC. We present progress on this stabilization experiment including the design of a second-order isochronous bypass, as well as optimizations of the Dynamic Aperture (DA) and injection efficiency.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS030

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Received ※ 08 June 2022 — Revised ※ 17 June 2022 — Accepted ※ 23 June 2022 — Issue date ※ 26 June 2022

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WEPOMS031

Light Path Construction for an Optical Stochastic Cooling Stability Test at the Cornell Electron Storage Ring

2315

S.J. Levenson, M.B. Andorf, I.V. Bazarov, D.C. Burke, J.M. Maxson, D.L. Rubin, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: This work was supported by the U.S. National Science Foundation under Award PHY-1549132, the Center for Bright Beams and NYSTAR award C150153.
An experiment at the Cornell Electron Storage Ring (CESR) to test the optical path-length stability of a bypass suitable for Optical Stochastic Cooling (OSC) is being pursued. The approximately 80 m light path for this experiment has been assembled, and synchrotron light has been successfully propagated from both sources. A feedback system based on an Electro-Optic Modulator (EOM) to correct the path-error accumulated in both the light and particle path has been table-top tested. We present on the design and construction of the light optics for the OSC stability experiment at CESR.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS031

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Received ※ 08 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 21 June 2022 — Issue date ※ 03 July 2022

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WEPOMS032

Simulations of Coherent Electron Cooling with Orbit Deviation

2319

J. Ma, V. Litvinenko, G. Wang
BNL, Upton, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
Coherent electron cooling (CeC) is a novel technique for rapidly cooling high-energy, high-intensity hadron beam. Plasma cascade amplifier (PCA) has been proposed for the CeC experiment in the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL). Cooling performance of PCA based CeC has been predicted in 3D start-to-end CeC simulations using code SPACE. The dependence of the PCA gain and the cooling rate on the electron beam’s orbit deviation has been explored in the simulation studies.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOMS032

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Received ※ 16 May 2022 — Revised ※ 11 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 29 June 2022

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