LINAC2014 - List of Keywords (undulator)

Paper	Title	Other Keywords	Page
MOIOB04	Current Status of PAL-XFEL	gun, linac, electron, experiment	26
	I.S. Ko, J.H. Han PAL, Pohang, Kyungbuk, Republic of Korea
	The PAL-XFEL project aims to produce 0.1~nm coherent X-ray laser to photon beam users. In order to produce such photons, there are 10 GeV electron linac based on S-band normal conducting accelerating structures and a 150 m long out-vacuum undulator system. The project was already started in April 2011, and the 1.1 km long building is expected to be completed by December 2014. The injector test facility (ITF) which is for a test of the first 139 MeV section of the main linac has been installed and is in normal operation at the extension of the PLS linac building. In this paper, we introduce the project in general, a brief summary of site preparation and building construction, beam test results of ITF, and test results of subsystems produced by domestic manufacturers
	Slides MOIOB04 [9.901 MB]

MOPP083	Helical Waveguides for Short Wavelength Accelerators and RF Undulators	electron, FEL, focusing, radiation	248
	S.V. Kuzikov, A.V. Savilov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia A.V. Savilov NNGU, Nizhny Novgorod, Russia
	The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.
	Poster MOPP083 [2.139 MB]

MOPP098	Physical Starting of the First and Second Section of Accelerator Linac-800	electron, klystron, linac, gun	288
	V. Kobets, N. Balalykin, I.N. Meshkov, V. Minashkin, G. Shirkov JINR, Dubna, Moscow Region, Russia V. Shabratov JINR/VBLHEP, Moscow, Russia
	In the report discusses the modernization of linear electron accelerator MEA (Medium Energy Accelerator). The aim is to develop a set of MEAs based free-electron lasers, imposed a number of emission wavelengths from infrared to ultraviolet. In work presents the results of the physical starting of the first and second stations accelerating electron linear accelerator LINAC-800, as well as start infrared undulator. We discuss the work program for this accelerator.

MOPP127	Wakefield Effects of the Bypass Line in LCLS-II	dipole, wakefield, operation, acceleration	355
	K.L.F. Bane, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE–AC02–76SF00515. In LCLS-II, after acceleration and compression and just before entering the undulator, the beam passes through roughly 2.5 km of 24.5 mm (radius) stainless steel pipe. The bunch that passes through the pipe is extremely short with an rms of 8 um for the nominal 100 pC case. Thus, even though the pipe has a large aperture, the wake that applies is the short-range resistive wall wakefield. It turns out that the wake supplies needed dechirping to the LCLS-II beam before it enters the undulator. The LCLS-II bunch distribution is approximately uniform, and therefore the wake induced voltage is characterized by a rather linear voltage chirp for short bunches. However for bunches longer than 25 um (300 pC at 1 kA) the wake starts to become nonlinear, effectively limiting the maximum charge with which the LCLS-II can operate. In this note we calculate the wake, discuss the confidence in the calculation, and investigate how to improve the induced chirp linearity and/or strength. Finally, we also study the strength and effects of the transverse (dipole) resistive wall wakefield.

TUIOA04	The New LCLS-II Project : Status and Challenges	linac, cryomodule, electron, operation	404
	J.N. Galayda SLAC, Menlo Park, California, USA
	The LCLS-II was an upgrade of the LCLS which essentially replicated the LCLS in another tunnel using the middle 1/3 of the SLAC S-band linac. In August 2013, the project was doubled in scope and redirected towards providing MHz-rate X-ray pulses from 0.2 to 5.0 keV while still supporting the ongoing program at the LCLS. The accelerator is now based on a 4.0 GeV SCRF linac installed in the front of the SLAC linac tunnel. Status and challenges of LCLS-II in context of July 2013 recommendation of DOE BESAC for a fully coherent, cw, FEL with photon energies up to ~5 keV.
	Slides TUIOA04 [6.386 MB]

TUPP020	Beam Dynamics Simulation for FLASH2 HGHG Option	simulation, FEL, radiation, electron	471
	G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov DESY, Hamburg, Germany K.E. Hacker DELTA, Dortmund, Germany T. Plath Uni HH, Hamburg, Germany
	The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP122	Roughness Tolerances in the Undulator Vacuum Chamber of LCLS-II	impedance, vacuum, wakefield, FEL	708
	K.L.F. Bane, G.V. Stupakov SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE–AC02–76SF00515. In LCLS-II, after acceleration and compression and just before entering the undulator, the beam passes through roughly 2.5 km of 24.5 mm (radius) stainless steel pipe. The bunch that passes through the pipe is extremely short with an rms of 8 um for the nominal 100 pC case. Thus, even though the pipe has a large aperture, the wake that applies is the short-range resistive wall wakefield. It turns out that the wake supplies needed dechirping to the LCLS-II beam before it enters the undulator. The LCLS-II bunch distribution is approximately uniform, and therefore the wake induced voltage is characterized by a rather linear voltage chirp for short bunches. However for bunches longer than 25 um (300 pC at 1 kA) the wake starts to become nonlinear, effectively limiting the maximum charge with which the LCLS-II can operate. In this note we calculate the wake, discuss the confidence in the calculation, and investigate how to improve the induced chirp linearity and/or strength. Finally, we also study the strength and effects of the transverse (dipole) resistive wall wakefield.

THIOB03	Results From the LCLS X-Band Transverse Deflector With Femtosecond Temporal Resolution	electron, FEL, photon, diagnostics	819
	Y. Ding, F.-J. Decker, V.A. Dolgashev, J.C. Frisch, Z. Huang, P. Krejcik, H. Loos, A. Lutmann, A. Marinelli, T.J. Maxwell, D.F. Ratner, J.L. Turner, J.W. Wang, M.-H. Wang, J.J. Welch, J. Wu SLAC, Menlo Park, California, USA C. Behrens DESY, Hamburg, Germany
	An X-band RF transverse deflector composed of two 1-m-long X-band deflecting structures has been recently commissioned at the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory. Located downstream of the FEL undulator, this device provides electron beam longitudinal phase space diagnostics in both time and energy which enables reconstruction of the X-ray FEL power profiles with an unprecedented resolution. This talk reports on the progress of this new LCLS X-band transverse deflector, first usage experience and measured results.
	Slides THIOB03 [3.508 MB]

THPP084	Cyclotron-Undulator Cooling of Electron Beams	electron, cyclotron, FEL, simulation	1041
	S.V. Kuzikov, I.V. Bandurkin, A.V. Savilov IAP/RAS, Nizhny Novgorod, Russia A.V. Savilov NNGU, Nizhny Novgorod, Russia
	XFELs require high-quality electron beams which can be produced in damping rings. For XFEL, based on Compton scattering of laser light, instead of the damping ring we consider a new compact device where electrons move in the undulator with axial DC magnetic field. In this undulator electrons move near resonant condition, rotating with cyclotron frequency and wiggling at similar bounce frequency. Such undulator allows compensation of the initial velocity spread by perturbations of the longitudinal velocities caused by transverse wiggling. Calculation show that ~1% velocity spread of 5 MeV electron beam (typical for photoinjectors) can be reduced to ~0.01% at distance as long as 20 undulator periods. In the advanced scheme, where the described undulators alternate with sections of the cyclotron radiation, energy spread as small as 0.001% is reachable. Calculations show that this principle works also for high energy beams (100 MeV and more), where RF undulator instead of DC-magnet undulator is preferable.
	Poster THPP084 [0.713 MB]

Paper

Title

Other Keywords

Page

MOIOB04

Current Status of PAL-XFEL

gun, linac, electron, experiment

26

I.S. Ko, J.H. Han
PAL, Pohang, Kyungbuk, Republic of Korea

The PAL-XFEL project aims to produce 0.1~nm coherent X-ray laser to photon beam users. In order to produce such photons, there are 10 GeV electron linac based on S-band normal conducting accelerating structures and a 150 m long out-vacuum undulator system. The project was already started in April 2011, and the 1.1 km long building is expected to be completed by December 2014. The injector test facility (ITF) which is for a test of the first 139 MeV section of the main linac has been installed and is in normal operation at the extension of the PLS linac building. In this paper, we introduce the project in general, a brief summary of site preparation and building construction, beam test results of ITF, and test results of subsystems produced by domestic manufacturers

Slides MOIOB04 [9.901 MB]

MOPP083

Helical Waveguides for Short Wavelength Accelerators and RF Undulators

electron, FEL, focusing, radiation

248

S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
A.V. Savilov
NNGU, Nizhny Novgorod, Russia

The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.

Poster MOPP083 [2.139 MB]

MOPP098

Physical Starting of the First and Second Section of Accelerator Linac-800

electron, klystron, linac, gun

288

V. Kobets, N. Balalykin, I.N. Meshkov, V. Minashkin, G. Shirkov
JINR, Dubna, Moscow Region, Russia
V. Shabratov
JINR/VBLHEP, Moscow, Russia

In the report discusses the modernization of linear electron accelerator MEA (Medium Energy Accelerator). The aim is to develop a set of MEAs based free-electron lasers, imposed a number of emission wavelengths from infrared to ultraviolet. In work presents the results of the physical starting of the first and second stations accelerating electron linear accelerator LINAC-800, as well as start infrared undulator. We discuss the work program for this accelerator.

MOPP127

Wakefield Effects of the Bypass Line in LCLS-II

dipole, wakefield, operation, acceleration

355

K.L.F. Bane, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE–AC02–76SF00515.
In LCLS-II, after acceleration and compression and just before entering the undulator, the beam passes through roughly 2.5 km of 24.5 mm (radius) stainless steel pipe. The bunch that passes through the pipe is extremely short with an rms of 8 um for the nominal 100 pC case. Thus, even though the pipe has a large aperture, the wake that applies is the short-range resistive wall wakefield. It turns out that the wake supplies needed dechirping to the LCLS-II beam before it enters the undulator. The LCLS-II bunch distribution is approximately uniform, and therefore the wake induced voltage is characterized by a rather linear voltage chirp for short bunches. However for bunches longer than 25 um (300 pC at 1 kA) the wake starts to become nonlinear, effectively limiting the maximum charge with which the LCLS-II can operate. In this note we calculate the wake, discuss the confidence in the calculation, and investigate how to improve the induced chirp linearity and/or strength. Finally, we also study the strength and effects of the transverse (dipole) resistive wall wakefield.

TUIOA04

The New LCLS-II Project : Status and Challenges

linac, cryomodule, electron, operation

404

J.N. Galayda
SLAC, Menlo Park, California, USA

The LCLS-II was an upgrade of the LCLS which essentially replicated the LCLS in another tunnel using the middle 1/3 of the SLAC S-band linac. In August 2013, the project was doubled in scope and redirected towards providing MHz-rate X-ray pulses from 0.2 to 5.0 keV while still supporting the ongoing program at the LCLS. The accelerator is now based on a 4.0 GeV SCRF linac installed in the front of the SLAC linac tunnel. Status and challenges of LCLS-II in context of July 2013 recommendation of DOE BESAC for a fully coherent, cw, FEL with photon energies up to ~5 keV.

Slides TUIOA04 [6.386 MB]

TUPP020

Beam Dynamics Simulation for FLASH2 HGHG Option

simulation, FEL, radiation, electron

471

G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov
DESY, Hamburg, Germany
K.E. Hacker
DELTA, Dortmund, Germany
T. Plath
Uni HH, Hamburg, Germany

The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP122

Roughness Tolerances in the Undulator Vacuum Chamber of LCLS-II

impedance, vacuum, wakefield, FEL

708

K.L.F. Bane, G.V. Stupakov
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE–AC02–76SF00515.
In LCLS-II, after acceleration and compression and just before entering the undulator, the beam passes through roughly 2.5 km of 24.5 mm (radius) stainless steel pipe. The bunch that passes through the pipe is extremely short with an rms of 8 um for the nominal 100 pC case. Thus, even though the pipe has a large aperture, the wake that applies is the short-range resistive wall wakefield. It turns out that the wake supplies needed dechirping to the LCLS-II beam before it enters the undulator. The LCLS-II bunch distribution is approximately uniform, and therefore the wake induced voltage is characterized by a rather linear voltage chirp for short bunches. However for bunches longer than 25 um (300 pC at 1 kA) the wake starts to become nonlinear, effectively limiting the maximum charge with which the LCLS-II can operate. In this note we calculate the wake, discuss the confidence in the calculation, and investigate how to improve the induced chirp linearity and/or strength. Finally, we also study the strength and effects of the transverse (dipole) resistive wall wakefield.

THIOB03

Results From the LCLS X-Band Transverse Deflector With Femtosecond Temporal Resolution

electron, FEL, photon, diagnostics

819

Y. Ding, F.-J. Decker, V.A. Dolgashev, J.C. Frisch, Z. Huang, P. Krejcik, H. Loos, A. Lutmann, A. Marinelli, T.J. Maxwell, D.F. Ratner, J.L. Turner, J.W. Wang, M.-H. Wang, J.J. Welch, J. Wu
SLAC, Menlo Park, California, USA
C. Behrens
DESY, Hamburg, Germany

An X-band RF transverse deflector composed of two 1-m-long X-band deflecting structures has been recently commissioned at the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory. Located downstream of the FEL undulator, this device provides electron beam longitudinal phase space diagnostics in both time and energy which enables reconstruction of the X-ray FEL power profiles with an unprecedented resolution. This talk reports on the progress of this new LCLS X-band transverse deflector, first usage experience and measured results.

Slides THIOB03 [3.508 MB]

THPP084

Cyclotron-Undulator Cooling of Electron Beams

electron, cyclotron, FEL, simulation

1041

S.V. Kuzikov, I.V. Bandurkin, A.V. Savilov
IAP/RAS, Nizhny Novgorod, Russia
A.V. Savilov
NNGU, Nizhny Novgorod, Russia

XFELs require high-quality electron beams which can be produced in damping rings. For XFEL, based on Compton scattering of laser light, instead of the damping ring we consider a new compact device where electrons move in the undulator with axial DC magnetic field. In this undulator electrons move near resonant condition, rotating with cyclotron frequency and wiggling at similar bounce frequency. Such undulator allows compensation of the initial velocity spread by perturbations of the longitudinal velocities caused by transverse wiggling. Calculation show that ~1% velocity spread of 5 MeV electron beam (typical for photoinjectors) can be reduced to ~0.01% at distance as long as 20 undulator periods. In the advanced scheme, where the described undulators alternate with sections of the cyclotron radiation, energy spread as small as 0.001% is reachable. Calculations show that this principle works also for high energy beams (100 MeV and more), where RF undulator instead of DC-magnet undulator is preferable.

Poster THPP084 [0.713 MB]