NAPAC2019 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MOZBA1	LCLS-II SC Linac: Challenges and Status	cavity, cryomodule, SRF, linac	51
	M.C. Ross SLAC, Menlo Park, California, USA
	Funding: ∗ This work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515 The Linac Coherent Light Source II (LCLS-II) project requires the assembly, test, and installation of 37 cry-omodules (CM) in order to deliver a 4 GeV CW electron beam to the FEL undulators for production of both hard and soft X-ray pulses at a repetition rate of up to 1 MHz. All of the cryomodules will operation in continuous wave mode, with 35 operating at 1.3 GHz for acceleration and 2 operating at 3.9 GHz to linearize the longitudinal beam profile. The assembly and testing of the 1.3 GHz cry-omodules is nearing completion and the 3.9 GHz cry-omodules work is entering to assembly and testing phase. Roughly 60% of the cryomodules have been shipped to SLAC for installation in the accelerator enclosure. The status and challenges of these efforts will be reported in this paper.
	Slides MOZBA1 [80.533 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA1
About •	paper received ※ 02 September 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019
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MOZBA4	Recent Developments in High Power High Brightness Double Bunch Self-Seeding at LCLS-II	undulator, photon, electron, simulation	67
	A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, A.A. Lutman, G. Marcus, C. Pellegrini SLAC, Menlo Park, California, USA
	We discuss the power and spectral characteristics of an X-ray FEL, LCLS-II, operating in a double bunch self-seeding scheme (DBFEL). We show that it can reach very high power levels in the photon energy range of 4-8 keV. We discuss the system implementation on LCLS-II, including the design of a four-bounce crystal monochromator, and linac wakefields effects. Finally, we offer multiple applications of the DBFEL for high-field QED, AMO physics and single particle imaging.
	Slides MOZBA4 [3.175 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA4
About •	paper received ※ 02 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019
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MOPLO01	A Beam Spreader System for LCLS-II	kicker, septum, undulator, electron	236
	T.G. Beukers, J.W. Amann, Y.M. Nosochkov SLAC, Menlo Park, California, USA
	For the LCLS-II project, the SLAC National Accelerator Laboratory is installing a new superconducting RF linac capable of continuously delivering 4 GeV electron bunches spaced 1.1 microseconds apart. A spreader system is required to distribute the beam between a soft X-ray or hard X-ray undulator, and a beam dump. An additional beam diverter is required in the front end of the linac to divert 100 MeV electrons to a diagnostic line. Both the spreader and diagnostic diversion systems are designed to operate on a bunch by bunch basis via the combination of fast kickers and a Lambertson septum. This paper presents a summary of the optics, kicker, and septum design. Of specific interest is the unique challenge associated with building a high repetition, high stability, spreader capable of diverting a single bunch without disturbing neighboring bunches. Additional discussion includes the application of the spreader technology to the proposed DASEL/S30XL beamline. This beamline will acceptμbunches evenly spaced between the undulator bound bunches, thus requiring a kicker with the same repetition rate as LCLS-II but a pulse width extended to approximately 600 ns.
	Poster MOPLO01 [1.256 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO01
About •	paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019
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MOPLO23	Investigation of Various Fabrication Methods to Produce a 180GHz Corrugated Waveguide Structure in 2mm Diameter 0.5m Long Copper Tube for the Compact Wakefield Accelerator for FEL Facility	GUI, laser, electron, wakefield	286
	K.J. Suthar, D.S. Doran, W.G. Jansma, S.S. Sorsher, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents ANL, Lemont, Illinois, USA A.E. Siy UW-Madison/PD, Madison, Wisconsin, USA
	Funding: This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated by the Argonne National Laboratory under Contract No. DEAC0206CH11357. Argonne National Laboratory is developing a 180 GHz wakefield structure that will house in a co-linear array of accelerators to produce free-electron laser-based X-rays. The proposed corrugated waveguide structure will be fabricated on the internal wall of 0.5m long and 2mm nominal diameter copper tube. The estimated dimensions of these parallel corrugations are 200 µm in pitch with 100 µm side length (height and width). The length scale of the structure and requirements of the magnetic field-driven dimensional tolerances have made the structure challenging to produce. We have employed several method such as optical lithography, electroforming, electron discharge machining, laser ablation, and stamping to produce the initial structure from a sheet form. The successive fabrication steps, such as bending, brazing, and welding, were performed to achieve the long tubular-structure. This paper discusses various fabrication techniques, characterization, and associated technical challenges in detail. [1] A. Zholents et al., Proc. 9-th Intern. Part. Acc. Conf., IPAC2018, Vancouver, BC, Canada, p. 1266, (2018)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO23
About •	paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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TUPLH09	Thermal Effects on Bragg Diffraction of XFEL Optics	photon, optics, simulation, synchrotron	506
	Z. Qu, J. Wu, G. Zhou SLAC, Menlo Park, California, USA Y. Ma, Z. Qu UC Merced, Merced, California, USA B. Yang Western Digital, Milpitas, California, USA
	Funding: The US Department of Energy (DOE) (DE-AC02-76SF00515); The US DOE Office of Science Early Career Research Program grant (FWP-2013-SLAC-100164). Crystal optical devices are widely used in X-ray free electron laser (XFEL) systems, monochromators, beam splitters, high-reflectance backscattering mirrors, lenses, phase plates, diffraction gratings, and spectrometers. The absorption of X-ray in these optical devices can cause increase of temperature and consequent thermal deformation, which can dynamic change in optic output. In self-seeding XFEL, the thermal deformation and strain in monochromator could cause significant seed quality degradation: central energy shift, band broadening and reduction in seed power. To quantitatively estimate the impact of thermomechanical effects on seed quality, we conduct thermomechanical simulations combined with diffraction to evaluate the seed quality with residual temperature field in a pump-probe manner. With our results, we show that a critical repetition rate could be determined, once the criteria for deviation of the seed quality are selected. This tool shows great potential for the design of XFEL optics for stable operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH09
About •	paper received ※ 28 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019
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TUPLH10	Fabrication Progress of a Superconducting Helical Undulator with Superimposed Focusing Gradient for High Efficiency Tapered X-Ray FELs	undulator, quadrupole, vacuum, focusing	509
	S.M. Lynam, R.B. Agustsson, I.I. Gadjev, A.Yu. Smirnov RadiaBeam, Santa Monica, California, USA F.H. O’Shea Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Funding: This work is supported by DOE grant no. DE-SC0017072, "Superconducting Helical Undulator with Superimposed Focusing Gradient for High Efficiency Tapered X-Ray FELs" The Advanced Gradient Undulator (AGU) represents a potentially significant advancement in x-ray conversion efficiency for x-ray FELs. This increase in efficiency would have broad implications on the capabilities of x-ray light sources. To achieve this high conversion efficiency, the inner diameter of the undulator coil is a mere 7mm, even with the use of superconducting coils. To accommodate the beamline at the Advanced Photon Source this yields in a chamber with a wall thickness of 0.5mm fabricated from Aluminum. With a period of 2cm and a conductor position tolerance of <100 µm over a length of >80cm at 4.2K, the engineering and fabrication challenges for the undulator alone are substantial. We will discuss these fabrication challenges and present solutions to meet the tolerances required for desired performance, and provide an update on current progress of the construction of a section of the AGU insertion device.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH10
About •	paper received ※ 28 August 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019
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TUPLH24	Performance of CeC PoP Accelerator	electron, gun, SRF, hadron	526
	I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, I. Petrushina, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman BNL, Upton, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Coherent electron cooling experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed.
	Poster TUPLH24 [11.180 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH24
About •	paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019
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TUPLE13	Analytical Thermal Analysis of Thin Diamond in High-Intensity High-Repetition-Rate Application	laser, electron, operation, free-electron-laser	587
	Y. Hong, B. Yang University of Texas at Arlington, Arlington, USA J. Wu, G. Zhou SLAC, Menlo Park, California, USA
	Thin diamond plates are used in monochromator for X-ray Free-Electron Laser self-seeding scheme. To function properly, they must endure high-intensity and high-repetition-rate laser pulses without crossing thresholds set by various adverse effects, such as thermal strain-induced diffraction distortion and graphitization. In this work, a theoretical model is developed, and an analytical solution is derived to elucidate potential thermal runaway under edge cooling condition. It is shown that the crystal edge cooling can effectively mitigate the issue to a certain extent. The analytical solution can be used as an efficient tool for XFEL operation parameter setup.
	Poster TUPLE13 [0.939 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLE13
About •	paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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WEXBB1	Adaptive Machine Learning and Automatic Tuning of Intense Electron Bunches in Particle Accelerators	electron, controls, feedback, target	609
	A. Scheinker LANL, Los Alamos, New Mexico, USA
	Machine learning and in particular neural networks, have been around for a very long time. In recent years, thanks to growth in computing power, neural networks have reshaped many fields of research, including self driving cars, computers playing complex video games, image identification, and even particle accelerators. In this tutorial, I will first present an introduction to machine learning for beginners and will also touch on a few aspects of adaptive control theory. I will then introduce some problems in particle accelerators and present how they have been approached utilizing machine learning techniques as well as adaptive machine learning approaches, for automatically tuning extremely short and high intensity electron bunches in free electron lasers.
	Slides WEXBB1 [58.913 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEXBB1
About •	paper received ※ 28 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019
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WEYBA3	Tolerances for Plasma Wakefield Acceleration Drivers	plasma, luminosity, emittance, acceleration	614
	G.R. White, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	Transverse jitter tolerances are considered for beam-driven plasma accelerators. A simple model for jitter transfer from the drive to witness beam was developed and con-crete examples were studied for: high-brightness witness bunch injectors; high-energy boosters for FEL’s; and future Linear Colliders. For the LC application, we con-sider a superconducting Linac designed to minimize the jitter conditions of the drive beam. We use a start-to-end tracking model to simulate expected jitter performance. The tolerances on each subsystem of the driver Linac are found to be very tight, especially for magnet vibration which must be controlled at the sub-nm level. Work supported by the Department of Energy under Contract Number: DE-AC02-76SF00515.
	Slides WEYBA3 [6.178 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBA3
About •	paper received ※ 27 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019
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THXBA3	Adaptive Machine Learning and Feedback Control for Automatic Particle Accelerator Tuning	electron, controls, target, laser	916
	A. Scheinker LANL, Los Alamos, New Mexico, USA
	Free electron lasers (FEL) and plasma wakefield accelerators (PWA) are creating more and more complicated electron bunch configurations, including multi-color modes for FELs such as LCLS and LCLS-II and custom tailored bunch current profiles for PWAs such as FACET-II. These accelerators are also producing shorter and higher intensity bunches than before and require an ability to quickly switch between many different users with various specific phase space requirements. For some very exotic setups it can take hours of tuning to provide the beams that users require. In this work, we present results adaptive machine learning and model independent feedback techniques and their application in both the LCLS and European XFEL to 1) control electron bunch phase space to create desired current profiles and energy spreads by tuning FEL components automatically, 2) maximize the average pulse output energy of FELs by automatically tuning over 100 components simultaneously, 3) preliminary results on utilizing these techniques for non-invasive electron bunch longitudinal phase space diagnostics at PWAs.
	Slides THXBA3 [8.110 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THXBA3
About •	paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019
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FRXBA5	The Role of Laser Shaping in Microbunching Instability Suppression and Seeded X-Ray Free Electron Emission	laser, bunching, electron, experiment	990
	J. Tang, S. Carbajo, F.-J. Decker, Z. Huang, J. Krzywiński, R.A. Lemons, W. Liu, A.A. Lutman, G. Marcus, T.J. Maxwell, S.P. Moeller, D.F. Ratner, S. Vetter SLAC, Menlo Park, California, USA
	Microbunching instability (MBI) driven by collective effects in an accelerator is known to be detrimental for the performance of X-ray free electron lasers. At the Linac Coherent Light Source (LCLS), laser heater (LH) system was installed to suppress the microbunching instability by inducing a small amount of slice energy spread to the electron beam. The distribution of the induced energy spread greatly effects MBI suppression and can be controlled by shaping the transverse profile of the heater laser. In this paper, we present theoretical and experimental results on utilizing a Laguerre-Gaussian 01 Mode (LG01) laser at LCLS to obtain better suppression of the instability. We demonstrate experimentally that Gaussian-shaped energy distribution is induced by LG01 mode LH and final microbunching gain is better suppressed. We finally discuss the role of LH spatial shaping in soft X-ray self-seeded (SXRSS) FEL emission and demonstrate that this LH configuration is capable of generating high spectral brightness FEL pulses.
	Slides FRXBA5 [3.162 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBA5
About •	paper received ※ 28 August 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019
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FRCHC2	Possibilities for Future Synchrotron Radiation Sources	electron, laser, free-electron-laser, radiation	1000
	M.-E. Couprie SOLEIL, Gif-sur-Yvette, France
	The landscape of present accelerator based light sources is drawn. The photon beam brightness increases opens new areas of user applications, both with the arrival of low emittance rings getting closer to diffraction limit and the advent of X-ray Free Electron Lasers, providing agility in terms of performance (two colors, attosecond pulse…). Finally, the path towards light sources using alternate accelerator schemes, such as plasma acceleration is discussed.
	Slides FRCHC2 [76.897 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRCHC2
About •	paper received ※ 04 September 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019
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Paper

Title

Other Keywords

Page

MOZBA1

LCLS-II SC Linac: Challenges and Status

cavity, cryomodule, SRF, linac

51

M.C. Ross
SLAC, Menlo Park, California, USA

Funding: ∗ This work was supported by the US Department of Energy (DOE) under contract DE-AC02-76SF00515
The Linac Coherent Light Source II (LCLS-II) project requires the assembly, test, and installation of 37 cry-omodules (CM) in order to deliver a 4 GeV CW electron beam to the FEL undulators for production of both hard and soft X-ray pulses at a repetition rate of up to 1 MHz. All of the cryomodules will operation in continuous wave mode, with 35 operating at 1.3 GHz for acceleration and 2 operating at 3.9 GHz to linearize the longitudinal beam profile. The assembly and testing of the 1.3 GHz cry-omodules is nearing completion and the 3.9 GHz cry-omodules work is entering to assembly and testing phase. Roughly 60% of the cryomodules have been shipped to SLAC for installation in the accelerator enclosure. The status and challenges of these efforts will be reported in this paper.

Slides MOZBA1 [80.533 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA1

About •

paper received ※ 02 September 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019

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MOZBA4

Recent Developments in High Power High Brightness Double Bunch Self-Seeding at LCLS-II

undulator, photon, electron, simulation

67

A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, A.A. Lutman, G. Marcus, C. Pellegrini
SLAC, Menlo Park, California, USA

We discuss the power and spectral characteristics of an X-ray FEL, LCLS-II, operating in a double bunch self-seeding scheme (DBFEL). We show that it can reach very high power levels in the photon energy range of 4-8 keV. We discuss the system implementation on LCLS-II, including the design of a four-bounce crystal monochromator, and linac wakefields effects. Finally, we offer multiple applications of the DBFEL for high-field QED, AMO physics and single particle imaging.

Slides MOZBA4 [3.175 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOZBA4

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paper received ※ 02 September 2019 paper accepted ※ 05 September 2019 issue date ※ 08 October 2019

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MOPLO01

A Beam Spreader System for LCLS-II

kicker, septum, undulator, electron

236

T.G. Beukers, J.W. Amann, Y.M. Nosochkov
SLAC, Menlo Park, California, USA

For the LCLS-II project, the SLAC National Accelerator Laboratory is installing a new superconducting RF linac capable of continuously delivering 4 GeV electron bunches spaced 1.1 microseconds apart. A spreader system is required to distribute the beam between a soft X-ray or hard X-ray undulator, and a beam dump. An additional beam diverter is required in the front end of the linac to divert 100 MeV electrons to a diagnostic line. Both the spreader and diagnostic diversion systems are designed to operate on a bunch by bunch basis via the combination of fast kickers and a Lambertson septum. This paper presents a summary of the optics, kicker, and septum design. Of specific interest is the unique challenge associated with building a high repetition, high stability, spreader capable of diverting a single bunch without disturbing neighboring bunches. Additional discussion includes the application of the spreader technology to the proposed DASEL/S30XL beamline. This beamline will acceptμbunches evenly spaced between the undulator bound bunches, thus requiring a kicker with the same repetition rate as LCLS-II but a pulse width extended to approximately 600 ns.

Poster MOPLO01 [1.256 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO01

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paper received ※ 27 August 2019 paper accepted ※ 31 August 2019 issue date ※ 08 October 2019

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MOPLO23

Investigation of Various Fabrication Methods to Produce a 180GHz Corrugated Waveguide Structure in 2mm Diameter 0.5m Long Copper Tube for the Compact Wakefield Accelerator for FEL Facility

GUI, laser, electron, wakefield

286

K.J. Suthar, D.S. Doran, W.G. Jansma, S.S. Sorsher, E. Trakhtenberg, G.J. Waldschmidt, A. Zholents
ANL, Lemont, Illinois, USA
A.E. Siy
UW-Madison/PD, Madison, Wisconsin, USA

Funding: This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated by the Argonne National Laboratory under Contract No. DEAC0206CH11357.
Argonne National Laboratory is developing a 180 GHz wakefield structure that will house in a co-linear array of accelerators to produce free-electron laser-based X-rays. The proposed corrugated waveguide structure will be fabricated on the internal wall of 0.5m long and 2mm nominal diameter copper tube. The estimated dimensions of these parallel corrugations are 200 µm in pitch with 100 µm side length (height and width). The length scale of the structure and requirements of the magnetic field-driven dimensional tolerances have made the structure challenging to produce. We have employed several method such as optical lithography, electroforming, electron discharge machining, laser ablation, and stamping to produce the initial structure from a sheet form. The successive fabrication steps, such as bending, brazing, and welding, were performed to achieve the long tubular-structure. This paper discusses various fabrication techniques, characterization, and associated technical challenges in detail.
[1] A. Zholents et al., Proc. 9-th Intern. Part. Acc. Conf., IPAC2018, Vancouver, BC, Canada, p. 1266, (2018)

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-MOPLO23

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paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019

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TUPLH09

Thermal Effects on Bragg Diffraction of XFEL Optics

photon, optics, simulation, synchrotron

506

Z. Qu, J. Wu, G. Zhou
SLAC, Menlo Park, California, USA
Y. Ma, Z. Qu
UC Merced, Merced, California, USA
B. Yang
Western Digital, Milpitas, California, USA

Funding: The US Department of Energy (DOE) (DE-AC02-76SF00515); The US DOE Office of Science Early Career Research Program grant (FWP-2013-SLAC-100164).
Crystal optical devices are widely used in X-ray free electron laser (XFEL) systems, monochromators, beam splitters, high-reflectance backscattering mirrors, lenses, phase plates, diffraction gratings, and spectrometers. The absorption of X-ray in these optical devices can cause increase of temperature and consequent thermal deformation, which can dynamic change in optic output. In self-seeding XFEL, the thermal deformation and strain in monochromator could cause significant seed quality degradation: central energy shift, band broadening and reduction in seed power. To quantitatively estimate the impact of thermomechanical effects on seed quality, we conduct thermomechanical simulations combined with diffraction to evaluate the seed quality with residual temperature field in a pump-probe manner. With our results, we show that a critical repetition rate could be determined, once the criteria for deviation of the seed quality are selected. This tool shows great potential for the design of XFEL optics for stable operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH09

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paper received ※ 28 August 2019 paper accepted ※ 13 September 2019 issue date ※ 08 October 2019

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TUPLH10

Fabrication Progress of a Superconducting Helical Undulator with Superimposed Focusing Gradient for High Efficiency Tapered X-Ray FELs

undulator, quadrupole, vacuum, focusing

509

S.M. Lynam, R.B. Agustsson, I.I. Gadjev, A.Yu. Smirnov
RadiaBeam, Santa Monica, California, USA
F.H. O’Shea
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Funding: This work is supported by DOE grant no. DE-SC0017072, "Superconducting Helical Undulator with Superimposed Focusing Gradient for High Efficiency Tapered X-Ray FELs"
The Advanced Gradient Undulator (AGU) represents a potentially significant advancement in x-ray conversion efficiency for x-ray FELs. This increase in efficiency would have broad implications on the capabilities of x-ray light sources. To achieve this high conversion efficiency, the inner diameter of the undulator coil is a mere 7mm, even with the use of superconducting coils. To accommodate the beamline at the Advanced Photon Source this yields in a chamber with a wall thickness of 0.5mm fabricated from Aluminum. With a period of 2cm and a conductor position tolerance of <100 µm over a length of >80cm at 4.2K, the engineering and fabrication challenges for the undulator alone are substantial. We will discuss these fabrication challenges and present solutions to meet the tolerances required for desired performance, and provide an update on current progress of the construction of a section of the AGU insertion device.

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH10

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paper received ※ 28 August 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019

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TUPLH24

Performance of CeC PoP Accelerator

electron, gun, SRF, hadron

526

I. Pinayev, Z. Altinbas, J.C. Brutus, A.J. Curcio, A. Di Lieto, T. Hayes, R.L. Hulsart, P. Inacker, Y.C. Jing, V. Litvinenko, J. Ma, G.J. Mahler, M. Mapes, K. Mernick, K. Mihara, T.A. Miller, M.G. Minty, G. Narayan, I. Petrushina, F. Severino, K. Shih, Z. Sorrell, J.E. Tuozzolo, E. Wang, G. Wang, A. Zaltsman
BNL, Upton, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling experiment is aimed for demonstration of the proof-of-principle demonstration of reduction energy spread of a single hadron bunch circulating in RHIC. The electron beam should have the required parameters and its orbit and energy should be matched to the hadron beam. In this paper we present the achieved electron beam parameters including emittance, energy spread, and other critical indicators. The operational issues as well as future plans are also discussed.

Poster TUPLH24 [11.180 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLH24

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paper received ※ 29 August 2019 paper accepted ※ 03 September 2019 issue date ※ 08 October 2019

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TUPLE13

Analytical Thermal Analysis of Thin Diamond in High-Intensity High-Repetition-Rate Application

laser, electron, operation, free-electron-laser

587

Y. Hong, B. Yang
University of Texas at Arlington, Arlington, USA
J. Wu, G. Zhou
SLAC, Menlo Park, California, USA

Thin diamond plates are used in monochromator for X-ray Free-Electron Laser self-seeding scheme. To function properly, they must endure high-intensity and high-repetition-rate laser pulses without crossing thresholds set by various adverse effects, such as thermal strain-induced diffraction distortion and graphitization. In this work, a theoretical model is developed, and an analytical solution is derived to elucidate potential thermal runaway under edge cooling condition. It is shown that the crystal edge cooling can effectively mitigate the issue to a certain extent. The analytical solution can be used as an efficient tool for XFEL operation parameter setup.

Poster TUPLE13 [0.939 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-TUPLE13

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paper received ※ 27 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019

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WEXBB1

Adaptive Machine Learning and Automatic Tuning of Intense Electron Bunches in Particle Accelerators

electron, controls, feedback, target

609

A. Scheinker
LANL, Los Alamos, New Mexico, USA

Machine learning and in particular neural networks, have been around for a very long time. In recent years, thanks to growth in computing power, neural networks have reshaped many fields of research, including self driving cars, computers playing complex video games, image identification, and even particle accelerators. In this tutorial, I will first present an introduction to machine learning for beginners and will also touch on a few aspects of adaptive control theory. I will then introduce some problems in particle accelerators and present how they have been approached utilizing machine learning techniques as well as adaptive machine learning approaches, for automatically tuning extremely short and high intensity electron bunches in free electron lasers.

Slides WEXBB1 [58.913 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEXBB1

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paper received ※ 28 August 2019 paper accepted ※ 06 September 2019 issue date ※ 08 October 2019

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WEYBA3

Tolerances for Plasma Wakefield Acceleration Drivers

plasma, luminosity, emittance, acceleration

614

G.R. White, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Transverse jitter tolerances are considered for beam-driven plasma accelerators. A simple model for jitter transfer from the drive to witness beam was developed and con-crete examples were studied for: high-brightness witness bunch injectors; high-energy boosters for FEL’s; and future Linear Colliders. For the LC application, we con-sider a superconducting Linac designed to minimize the jitter conditions of the drive beam. We use a start-to-end tracking model to simulate expected jitter performance. The tolerances on each subsystem of the driver Linac are found to be very tight, especially for magnet vibration which must be controlled at the sub-nm level.
Work supported by the Department of Energy under Contract Number: DE-AC02-76SF00515.

Slides WEYBA3 [6.178 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-WEYBA3

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paper received ※ 27 August 2019 paper accepted ※ 02 September 2019 issue date ※ 08 October 2019

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THXBA3

Adaptive Machine Learning and Feedback Control for Automatic Particle Accelerator Tuning

electron, controls, target, laser

916

A. Scheinker
LANL, Los Alamos, New Mexico, USA

Free electron lasers (FEL) and plasma wakefield accelerators (PWA) are creating more and more complicated electron bunch configurations, including multi-color modes for FELs such as LCLS and LCLS-II and custom tailored bunch current profiles for PWAs such as FACET-II. These accelerators are also producing shorter and higher intensity bunches than before and require an ability to quickly switch between many different users with various specific phase space requirements. For some very exotic setups it can take hours of tuning to provide the beams that users require. In this work, we present results adaptive machine learning and model independent feedback techniques and their application in both the LCLS and European XFEL to 1) control electron bunch phase space to create desired current profiles and energy spreads by tuning FEL components automatically, 2) maximize the average pulse output energy of FELs by automatically tuning over 100 components simultaneously, 3) preliminary results on utilizing these techniques for non-invasive electron bunch longitudinal phase space diagnostics at PWAs.

Slides THXBA3 [8.110 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-THXBA3

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paper received ※ 27 August 2019 paper accepted ※ 15 September 2019 issue date ※ 08 October 2019

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FRXBA5

The Role of Laser Shaping in Microbunching Instability Suppression and Seeded X-Ray Free Electron Emission

laser, bunching, electron, experiment

990

J. Tang, S. Carbajo, F.-J. Decker, Z. Huang, J. Krzywiński, R.A. Lemons, W. Liu, A.A. Lutman, G. Marcus, T.J. Maxwell, S.P. Moeller, D.F. Ratner, S. Vetter
SLAC, Menlo Park, California, USA

Microbunching instability (MBI) driven by collective effects in an accelerator is known to be detrimental for the performance of X-ray free electron lasers. At the Linac Coherent Light Source (LCLS), laser heater (LH) system was installed to suppress the microbunching instability by inducing a small amount of slice energy spread to the electron beam. The distribution of the induced energy spread greatly effects MBI suppression and can be controlled by shaping the transverse profile of the heater laser. In this paper, we present theoretical and experimental results on utilizing a Laguerre-Gaussian 01 Mode (LG01) laser at LCLS to obtain better suppression of the instability. We demonstrate experimentally that Gaussian-shaped energy distribution is induced by LG01 mode LH and final microbunching gain is better suppressed. We finally discuss the role of LH spatial shaping in soft X-ray self-seeded (SXRSS) FEL emission and demonstrate that this LH configuration is capable of generating high spectral brightness FEL pulses.

Slides FRXBA5 [3.162 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRXBA5

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paper received ※ 28 August 2019 paper accepted ※ 12 September 2019 issue date ※ 08 October 2019

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FRCHC2

Possibilities for Future Synchrotron Radiation Sources

electron, laser, free-electron-laser, radiation

1000

M.-E. Couprie
SOLEIL, Gif-sur-Yvette, France

The landscape of present accelerator based light sources is drawn. The photon beam brightness increases opens new areas of user applications, both with the arrival of low emittance rings getting closer to diffraction limit and the advent of X-ray Free Electron Lasers, providing agility in terms of performance (two colors, attosecond pulse…). Finally, the path towards light sources using alternate accelerator schemes, such as plasma acceleration is discussed.

Slides FRCHC2 [76.897 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2019-FRCHC2

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paper received ※ 04 September 2019 paper accepted ※ 16 November 2020 issue date ※ 08 October 2019

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