FEL2014 - List of Keywords (plasma)

Paper	Title	Other Keywords	Page
MOP047	A 200 μm-period Laser-driven Undulator	undulator, laser, electron, alignment	131
	F. Toufexis, T. Tang, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515 and the DARPA AXiS program. To reduce the linac energy required for a given synchrotron radiation wavelength, and hence the size of the device, a smaller undulator period with sufficient field strength is needed. In this work, a microfabricated, laser-driven undulator with 200um undulator period is proposed. A TE wave that co-propagates with the electron beam is excited between two polysilicon thin films, having a gap of 16.5um. The mode that is excited is a deflecting mode and causes the electron beam to wiggle. The device is fabricated on a silicon wafer, using conventional silicon micromachining techniques. A single polysilicon thin film is supported on a silicon chip, which has a slit from the back to allow delivery of the laser beam. Two such chips are bonded together to form a 16.5um gap, within which the electron beam passes through. The final device has dimensions 1cm x 1cm x 1.1mm and has approximately 35 undulator periods. In this paper, the model, design, fabrication, and cold measurements of the device are reported.

TUP014	Forward X-Ray and Ultraviolet Smith-Purcell Radiation for FEL	radiation, target, electron, polarization	384
	A.A. Tishchenko, D.Yu. Sergeeva MEPhI, Moscow, Russia
	The scheme of Free Electron Lasers based on Smith-Purcell effect is well known to describe the process of interaction between an electron beam and evanescent wave, which bunches this beam. In this work we concentrate on the process of generation of the radiation propagating at small angles. In terms of approach described in detail in,, we investigate the Smith-Purcell radiation at oblique incidence of a single charged particle for X-Ray and UV frequency region. This forward radiation propagates through all the region of the beam moving and provides more close interaction between the beam and the radiation, than usual surface waves existing in FELs. Spectral and angular characteristics of the forward radiation are discussed from point of view its role in Smith-Purcell based FELs. A.P.Potylitsyn, M.I.Ryazanov, M.N.Strikhanov, A.A.Tishchenko, Diffraction Radiation from Relativistic Particles, Springer, 2011 **D.Yu.Sergeeva, A.A.Tishchenko, M.N.Strikhanov, NIM B 309 (2013) 189

THP008	Evolution of a Warm Bunched Electron Beam in a Free Drift Region	electron, space-charge, FEL, bunching	692
	B. Maly, A. Friedman Ariel University, Ariel, Israel
	The state of the art of FELs development at present is "Table-Top X Ray Free Electron Lasers". Almost any such scheme involves a pre-bunched electron beam. In this paper we will analyze the evolution and "survivability" of bunching introduced into the beam in the free drift region prior to the wiggler. We examined analytically the first order degradation in beam bunching due to space charge effect. It will be shown that there is a limited interaction region, characterized by an exponential decay of the bunching factor, having a length inversely proportional to the square of the electron beam normalized temperature, followed by a stable bunch region. We will present examples of the effect for several schemes of X Ray and Tera Hertz FELs considered or being constructed presently.

THP035	Relativistic Effects in Micro-bunching	bunching, electron, space-charge, dipole	790
	V. Litvinenko Stony Brook University, Stony Brook, USA G. Wang BNL, Upton, Long Island, New York, USA
	In this paper we present our theoretical studies of limits on bunching using magnetic systems. We discuss the connection of this limit with plasma oscillations in electron beams and present simple formulae for an additional limit of micro-bunching amplification.

THP087	Electron Beam Diagnostics for COXINEL	electron, diagnostics, undulator, FEL	937
	M. Labat, C. Bourassin-Bouchet, L. Cassinari, M.-E. Couprie, M.E. El Ajjouri, N. Hubert, A. Loulergue SOLEIL, Gif-sur-Yvette, France
	On the path towards more compact free electron lasers (FELs), the project COXINEL was recently funded: a transfer line will be installed to adapt a plasma accelerated beam (from LOA) into an in-vacuum undulator built by SOLEIL. This experiment should enable to demonstrate the first FEL based on a plasma accelerator. Because plasma beams are intrinsically very different from RF acceletor beams (much shorter, divergent and smaller with a higher energy spread and energy jitter), their transport and matching in the undulator is critical if willing to obtain a significant amplification. This is why special care has to be taken in the design of the beam diagnostics to be able to measure the transverse beam sizes, energy spread and jitter, emittance and bunch length. For these purposes, several diagnostics will be implemented from the plasma accelerator exit down to the undulator exit. In each station, several screen types will be available and associated to high resolution imaging screens. In this paper, we present the experimental layout and associated simulation of the diagnostics performances.

FRA04	Optimization of High Average Power FEL Beam for EUV Lithography Application	FEL, laser, electron, optics	990
	A. Endo, K. Sakaue, M. Washio Waseda University, Tokyo, Japan H. Mizoguchi Gigaphoton Inc, Hiratsuka, Kanagawa, Japan
	Extreme Ultraviolet Lithography (EUVL) is realized with 100W plasma EUV source at 13.5nm. It is recommended by the EUVL community to evaluate an alternative approach based on high repetition rate FEL, to avoid the power limit of the plasma source. Several papers discuss on the possibility to realize superconducting FEL to generate multiple kW 13.5nm light. We must notice that the present SASE FEL pulse has higher beam fluence than the resist ablation threshold, and high spatial coherence which results in speckle patterns, and random longitudinal mode beat which leads to high peak powerμspikes. An expanding mirror is installed after the undulator to reduce the beam fluence, external-seeding configuration is employed to reduce the longitudinal mode beat, and total reflection beam homogenizer is used for spatial mode mixing. Pulse repetition rate is more than 3MHz to cancel the speckle patter formation by averaging illumination. This paper discusses on the lowest risk approach to construct a prototype to demonstrate a high average power 13.5nm FEL for the best optimization in EUVL application, including the scaling to 6.7nm wavelength. J. Chalupský, L. Juha et.al, “Characteristics of focused soft X-ray free-electron laser beam determined by ablation of organic molecular solids”, OPTICS EXPRESS 15, 6036 (2007)
	Slides FRA04 [1.413 MB]

FRB04	Divergence Reduction and Emittance Conservation in a Laser Plasma Acceleration Stage	laser, emittance, acceleration, extraction	999
	A.R. Maier, I. Dornmair CFEL, Hamburg, Germany K. Flöttmann DESY, Hamburg, Germany
	Plasma accelerators promise a compact source of highly relativistic electron beams. Driven by high-intensity lasers or high-energetic electron beams, the longitudinal and transverse electric fields inside the plasma cavitiy support the generation of GeV electron beams over m-scale distances, while measured emittances on the order of 0.1 mm.mrad have been reported from plasma-driven accelerators. However, it remains challenging to conserve this excellent emittance when coupling from the plasma into vacuum and a subsequent beam optics, especially when considering the large energy spread, typically accumulated during the off-crest acceleration inside the plasma. Recently, we presented an analytical solution [1] to describe an adiabatic matching from the plasma into vacuum. Further elaborating this concept [2], we will discuss the generation of low-divergence electron beams from a tailored plasma target in order to preserve the emittance generated within the plasma. We will apply our concept to an externally injected electron bunch, that is matched in and out of a tailored plasma target, generating a GeV-level electron beam with low divergence and good emittance. * K. Floettmann, Phys. Rev. ST - Accel. Beams 17, 054402 (2014) ** I. Dornmair, K. Floettmann, and A. R. Maier, submitted (2014)

Paper

Title

Other Keywords

Page

MOP047

A 200 μm-period Laser-driven Undulator

undulator, laser, electron, alignment

131

F. Toufexis, T. Tang, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515 and the DARPA AXiS program.
To reduce the linac energy required for a given synchrotron radiation wavelength, and hence the size of the device, a smaller undulator period with sufficient field strength is needed. In this work, a microfabricated, laser-driven undulator with 200um undulator period is proposed. A TE wave that co-propagates with the electron beam is excited between two polysilicon thin films, having a gap of 16.5um. The mode that is excited is a deflecting mode and causes the electron beam to wiggle. The device is fabricated on a silicon wafer, using conventional silicon micromachining techniques. A single polysilicon thin film is supported on a silicon chip, which has a slit from the back to allow delivery of the laser beam. Two such chips are bonded together to form a 16.5um gap, within which the electron beam passes through. The final device has dimensions 1cm x 1cm x 1.1mm and has approximately 35 undulator periods. In this paper, the model, design, fabrication, and cold measurements of the device are reported.

TUP014

Forward X-Ray and Ultraviolet Smith-Purcell Radiation for FEL

radiation, target, electron, polarization

384

A.A. Tishchenko, D.Yu. Sergeeva
MEPhI, Moscow, Russia

The scheme of Free Electron Lasers based on Smith-Purcell effect is well known to describe the process of interaction between an electron beam and evanescent wave, which bunches this beam. In this work we concentrate on the process of generation of the radiation propagating at small angles. In terms of approach described in detail in*,**, we investigate the Smith-Purcell radiation at oblique incidence of a single charged particle for X-Ray and UV frequency region. This forward radiation propagates through all the region of the beam moving and provides more close interaction between the beam and the radiation, than usual surface waves existing in FELs. Spectral and angular characteristics of the forward radiation are discussed from point of view its role in Smith-Purcell based FELs.
*A.P.Potylitsyn, M.I.Ryazanov, M.N.Strikhanov, A.A.Tishchenko, Diffraction Radiation from Relativistic Particles, Springer, 2011
**D.Yu.Sergeeva, A.A.Tishchenko, M.N.Strikhanov, NIM B 309 (2013) 189

THP008

Evolution of a Warm Bunched Electron Beam in a Free Drift Region

electron, space-charge, FEL, bunching

692

B. Maly, A. Friedman
Ariel University, Ariel, Israel

The state of the art of FELs development at present is "Table-Top X Ray Free Electron Lasers". Almost any such scheme involves a pre-bunched electron beam. In this paper we will analyze the evolution and "survivability" of bunching introduced into the beam in the free drift region prior to the wiggler. We examined analytically the first order degradation in beam bunching due to space charge effect. It will be shown that there is a limited interaction region, characterized by an exponential decay of the bunching factor, having a length inversely proportional to the square of the electron beam normalized temperature, followed by a stable bunch region. We will present examples of the effect for several schemes of X Ray and Tera Hertz FELs considered or being constructed presently.

THP035

Relativistic Effects in Micro-bunching

bunching, electron, space-charge, dipole

790

V. Litvinenko
Stony Brook University, Stony Brook, USA
G. Wang
BNL, Upton, Long Island, New York, USA

In this paper we present our theoretical studies of limits on bunching using magnetic systems. We discuss the connection of this limit with plasma oscillations in electron beams and present simple formulae for an additional limit of micro-bunching amplification.

THP087

Electron Beam Diagnostics for COXINEL

electron, diagnostics, undulator, FEL

937

M. Labat, C. Bourassin-Bouchet, L. Cassinari, M.-E. Couprie, M.E. El Ajjouri, N. Hubert, A. Loulergue
SOLEIL, Gif-sur-Yvette, France

On the path towards more compact free electron lasers (FELs), the project COXINEL was recently funded: a transfer line will be installed to adapt a plasma accelerated beam (from LOA) into an in-vacuum undulator built by SOLEIL. This experiment should enable to demonstrate the first FEL based on a plasma accelerator. Because plasma beams are intrinsically very different from RF acceletor beams (much shorter, divergent and smaller with a higher energy spread and energy jitter), their transport and matching in the undulator is critical if willing to obtain a significant amplification. This is why special care has to be taken in the design of the beam diagnostics to be able to measure the transverse beam sizes, energy spread and jitter, emittance and bunch length. For these purposes, several diagnostics will be implemented from the plasma accelerator exit down to the undulator exit. In each station, several screen types will be available and associated to high resolution imaging screens. In this paper, we present the experimental layout and associated simulation of the diagnostics performances.

FRA04

Optimization of High Average Power FEL Beam for EUV Lithography Application

FEL, laser, electron, optics

990

A. Endo, K. Sakaue, M. Washio
Waseda University, Tokyo, Japan
H. Mizoguchi
Gigaphoton Inc, Hiratsuka, Kanagawa, Japan

Extreme Ultraviolet Lithography (EUVL) is realized with 100W plasma EUV source at 13.5nm. It is recommended by the EUVL community to evaluate an alternative approach based on high repetition rate FEL, to avoid the power limit of the plasma source. Several papers discuss on the possibility to realize superconducting FEL to generate multiple kW 13.5nm light. We must notice that the present SASE FEL pulse has higher beam fluence than the resist ablation threshold*, and high spatial coherence which results in speckle patterns, and random longitudinal mode beat which leads to high peak powerμspikes. An expanding mirror is installed after the undulator to reduce the beam fluence, external-seeding configuration is employed to reduce the longitudinal mode beat, and total reflection beam homogenizer is used for spatial mode mixing. Pulse repetition rate is more than 3MHz to cancel the speckle patter formation by averaging illumination. This paper discusses on the lowest risk approach to construct a prototype to demonstrate a high average power 13.5nm FEL for the best optimization in EUVL application, including the scaling to 6.7nm wavelength.
*J. Chalupský, L. Juha et.al, “Characteristics of focused soft X-ray free-electron laser beam determined by ablation of organic molecular solids”, OPTICS EXPRESS 15, 6036 (2007)

Slides FRA04 [1.413 MB]

FRB04

Divergence Reduction and Emittance Conservation in a Laser Plasma Acceleration Stage

laser, emittance, acceleration, extraction

999

A.R. Maier, I. Dornmair
CFEL, Hamburg, Germany
K. Flöttmann
DESY, Hamburg, Germany

Plasma accelerators promise a compact source of highly relativistic electron beams. Driven by high-intensity lasers or high-energetic electron beams, the longitudinal and transverse electric fields inside the plasma cavitiy support the generation of GeV electron beams over m-scale distances, while measured emittances on the order of 0.1 mm.mrad have been reported from plasma-driven accelerators. However, it remains challenging to conserve this excellent emittance when coupling from the plasma into vacuum and a subsequent beam optics, especially when considering the large energy spread, typically accumulated during the off-crest acceleration inside the plasma. Recently, we presented an analytical solution [1] to describe an adiabatic matching from the plasma into vacuum. Further elaborating this concept [2], we will discuss the generation of low-divergence electron beams from a tailored plasma target in order to preserve the emittance generated within the plasma. We will apply our concept to an externally injected electron bunch, that is matched in and out of a tailored plasma target, generating a GeV-level electron beam with low divergence and good emittance.
* K. Floettmann, Phys. Rev. ST - Accel. Beams 17, 054402 (2014)
** I. Dornmair, K. Floettmann, and A. R. Maier, submitted (2014)