FEL2011 - Table of Session: TUPA (FEL Experiments and Projects)

Paper	Title	Page
TUPA01	Tunable THz-pulse-train Photoinjector	187
	Y.-C. Huang, F.H. Chao, C.H. Chen, H.H. Chen, K.Y. Huang NTHU, Hsinchu, Taiwan
	Funding: This work is jointly supported by the National Science Council, under Contract NSC97-2112-M-007-018-MY2; the National Synchrotron Radiation Research Center,under Project 955LRF01N. A THz-pulse-train photoinjector is under construction at the High-energy OPtics and Electronics (HOPE) Laboratory at National Tsinghua University, Taiwan. This photoinjector is believed to be useful for generating high-power THz radiation, as well as for driving or loading a plasma-wave accelerator. A THz laser beat wave with full tunability in its beat frequency is employed to induce the emission of the THz electron pulses from the photoinjector. We show in our study that such a photoinjector is capable of generating periodically bunched MeV electrons with a bunching factor larger than 0.1 at THz frequencies for a total amount of 1 nC charges in a 10-ps time duration. We will also present a driver laser technology that can tune the electron bunch frequency with ease and help the growth of the high harmonics in the bunching spectrum of accelerated electrons. Experimental progress on this photoinjector will be reported in the conference.

TUPA02	Development of Material Analysis Facility in KU-FEL	190
	K. Yoshida, M. A. Bakr, Y.W. Choi, H. Imon, K. Ishida, T. Kii, N. Kimura, R. Kinjo, K. Komai, K. Masuda, H. Ohgaki, M. Omer, S. Shibata, K. Shimahashi, T. Sonobe, H. Zen Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A mid infrared-free electron laser (MIR-FEL) (5-20 μm) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed for contributing to researches on energy science at Institute of Advanced Energy, Kyoto University. Up to now 12-14 μm FEL beam has been generated. When MIR-FEL with the wavelength matched to the molecular vibration mode is irradiated to the material, a particular chemical bond in the material will be selectively excited, or dissociated [1]. The selective photochemical reaction can be applied for surface modification and the evaluation of material in biochemistry, chemistry, and solid physics. Therefore, material analysis facility in combination with MIR-FEL is constructed. In the material analysis facility, advanced analysis systems such as photoluminescence measurement system, photoelectron spectroscopy, super centrifuge and high performance liquids chromatography, ICP emission spectroscopy, and high speed atomic force spectroscopy are installed. In this meeting, the development of material analysis facility will be introduced. [1] Jhon C.Tully, Science, 312(2006) 1004

TUPA04	sFLASH - Present Status and Commisioning Results	194
	V. Miltchev, S. Ackermann, A. Azima, J. Bödewadt, F. Curbis, M. Drescher, E. Hass, Th. Maltezopoulos, M. Mittenzwey, J. Rönsch-Schulenburg, J. Roßbach, R. Tarkeshian Uni HH, Hamburg, Germany H. Delsim-Hashemi, K. Honkavaara, T. Laarmann, H. Schlarb, S. Schreiber, M. Tischer DESY, Hamburg, Germany R. Ischebeck Paul Scherrer Institut, Villigen, Switzerland
	The free-electron laser in Hamburg (FLASH) was previously being operated in the self-amplified spontaneous emission (SASE) mode, producing photons in the XUV wavelength range. Due to the start-up from noise the SASE-radiation consists of a number of uncorrelated modes, which results in a reduced coherence. One option to simultaneously improve both the coherence and the synchronisation between the FEL-pulse and an external laser is to operate FLASH as an amplifier of a seed produced using high harmonics generation (HHG). An experimental set-up - sFLASH, has been installed to test this concept for the wavelengths below 40 nm. The sFLASH installation took place during the planed FLASH shutdown in the winter of 2009/2010. The technical commissioning, which began in the spring of 2010, has been followed by FEL-characterization and seeded-FEL commissioning in 2011. In this contribution the present status and the sFLASH commissioning results will be discussed.

TUPA06	Seeding Schemes on the French FEL Project LUNEX5	198
	C. Evain, F. Briquez, M.-E. Couprie, M. Labat, A. Loulergue SOLEIL, Gif-sur-Yvette, France V. Malka LOA, Palaiseau, France
	LUNEX5 is a single pass FEL project producing coherent synchrotron radiation with, in a first step, an electron bunch accelerated in conventional RF cavities up to 300 MeV. It is planned to work in a seeded configuration where the longitudinal coherence of the emitted light is improved and the gain length reduced, compared to the SASE configuration (Self-Amplified Spontaneous Emission). Two seeding schemes are considered: High order Harmonic in Gas seeding and EEHG scheme (Echo Enabled Harmonic Generation). Preliminary simulation results indicate that these two schemes permit to reach the saturation below a wavelength of 7 nm, and with less undulator periods for the EEHG scheme. Finally, the feasibility of plasma acceleration based FEL will also be investigated on this facility.

TUPA07	Study of a Silicon Based XFELO for the European XFEL	202
	J. Zemella, D. Novikov, M. Tolkiehn DESY, Hamburg, Germany J. Roßbach Uni HH, Hamburg, Germany H. Sinn European XFEL GmbH, Hamburg, Germany
	For the European XFEL in Hamburg three different SASE undulators are planed whose radiation output have a high peak brilliance up to 5.4·10³³ photon/s/mm²/mrad²/0.1% BW at wavelengths down to below 5·10^-11 m. The radiation pulses are nearly fully coherent in transverse direction but have a poor longitudinal coherence of about 0.3 fs. Several schemes were developed to get a better longitudinal coherence. In this paper an X-ray Free Electron Laser Oscillator is presented whose radiation output is nearly fully coherent in all directions. In contrast to previous schemes it is based on Silicon crystals rather than Diamond. The use of Silicon has the advantage of the availability of perfect crystals in nearly any size and crystal geometry but with a lower reflectivity and heat conduction than Diamond. To overcome the lower round-trip reflectivity of a Silicon cavity a longer undulator has to be used to get a sufficiently large gain. To reduce the heat load an extremely asymmetric crystal geometry has to be used to enlarge the beam spot on the crystal.

TUPA08	The Control System for CAEP FEL	206
	D. Zhang, M. Li, H.B. Wang, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	It describes a control system of CAEP Free Electron Laser (FEL), which is a distributed control system based on EPICS and Visual C++6.0. EPICS is popular in large accelerator laboratories in the world. It is a software toolkit for building process control system for a wide variety of experiment and industrial applications. The software tools in the kit provide independent and expandable modules for system configuration, distributed process control, run-time database, alarm manager, etc. It gives detailed description of the magnet power supply system , beam diagnostic system, including the hardware structure and software design. Other subsystems are also described in the paper. The control system has standard module, interoperability, and repeatability are available. The control system is simple direct, and stable.

TUPA09	LUNEX5: A FEL Project Towards the Fifth Generation in France	208
	M.-E. Couprie, C. Benabderrahmane, F. Briquez, J. Daillant, J.-C. Denard, C. Evain, P. Eymard, F. Ferrari, J.-M. Filhol, M. Labat, A. Loulergue, P. Marchand, C. Miron, P. Morin, F. Polack SOLEIL, Gif-sur-Yvette, France S. Bielawski, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France B. Carré CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France N. Delerue, R. Roux, A. Variola LAL, Orsay, France G. Lambert, V. Malka, A. Rousse LOA, Palaiseau, France J. Lüning CCPMR, Paris, France
	LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short intense and coherent pulses in the soft X rays region (down to 7 nm on the fifth harmonic). It comprises a free electron laser in the seeded configuration (High order Harmonic in Gas seeding and Echo Enable Harmonic Generation) using a conventional linear accelerator of 300 MeV. The FEL beamline including 15 m of in vacuum (potentially cryogenic undulators) of 15 and 30 mm period is designed so as to also accommodate a Laser Wake Field Accelerator (LWFA) ranging from 0.3 to 1 GeV, relying on electron beam parameters produced and accelerated by either the 60 TW laser of LOA or by the 10 PW APOLLON laser of ILE. After the completion and testing of the FEL with the conventional accelerator installed inside the SOLEIL booster inner area, the FEL line can be transported to a LWFA. A laser could alternatively be implemented at SOLEIL for starting testing the principles of a fifth generation light source.

TUPA11	Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II	212
	T. Tanikawa PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France M. Adachi, M. Katoh, J. Yamazaki, H. Zen UVSOR, Okazaki, Japan M. Hosaka, Y. Taira, N. Yamamoto Nagoya University, Nagoya, Japan
	Light source by using a laser seeding technique are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region, and also in generating CH with variable polarizations in deep UV [1]. In previous conferences, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependencies, and injection laser power dependencies on VUV CHs [2]. This time we have successfully observed saturation on CHs intensities and have found some interesting phenomena, which are the necessary power of injection laser to achieve the saturation of CHG is different in different harmonic orders, and the CH intensity is oscillated in deep saturated regime. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations. [1] M. Labat, et al., Phys. Rev. Lett. 101 (2008) 164803 [2] T. Tanikawa, et al., Prc. 1st Int. Particle Accelerator Conf., Kyoto, 2010. [3] T. Tanikawa, et al., Appl. Phys. Express 3 (2010) 122702

TUPA13	Present Status and Future Prospects of Project on Utilizing Coherent Light Sources for User Experiments at UVSOR-II	215
	H. Zen, K. Hayashi, S.I. Kimura, E. Nakamura, J. Yamazaki UVSOR, Okazaki, Japan M. Adachi, M. Katoh Sokendai - Okazaki, Okazaki, Aichi, Japan M. Hosaka, Y. Takashima, N. Yamamoto Nagoya University, Nagoya, Japan T. Takahashi Kyoto University, Research Reactor Institute, Osaka, Japan
	Funding: Quantum Beam Technology Program supported by JST/MEXT (Japan) We have been intensively developing coherent light sources utilizing electron bunches in the storage ring, UVSOR-II, by adding some external components to the ring. After successful generation of coherent synchrotron radiation (CSR) in THz range* and coherent harmonic generation (CHG) in DUV range** by using an intense driving laser, a 5-year new research project named as Quantum Beam Technology Program has been started from FY2008. The project includes introduction of new driving laser system, dedicated undulators and beamlines, and aims at utilizing those coherent radiations for user experiments. The new driving laser system has been installed last year. The undulators and beamlines are now under construction. Installation of those components will be finished before the conference. In the conference, we will report on the present status of system development and future plan of application experiments. M. Shimada et al., Japanese Journal of Applied Physics, vol. 46, pp. 7939-7944 (2007). *M. Labat et al., European Physical Journal D, vol. 44, pp. 187-200 (2007).

TUPA14	Conceptual Layout of a New Short-Pulse Radiation Source at DELTA Based on Echo-Enabled Harmonic Generation	219
	R. Molo, M. Bakr, H. Huck, M. Höner, S. Khan, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh DELTA, Dortmund, Germany
	As an upgrade of the present coherent harmonic generation (CHG) source at the DELTA storage ring, the installation of an additional undulator to implement and study the echo-enabled harmonic generation (EEHG) scheme [1] is planned. Compared to the CHG scheme, EEHG allows to produce radiation of shorter wavelengths, thus reaching more relevant absorption edges. In order to avoid dispersive distortions, all undulators should be placed along a straight line. This requires to increase the length of the present straight section by rearranging several magnets and vacuum components as well as a significant modification of the storage ring optics. [1] G. Stupakov, PRL 102, 074801 (2009)

TUPA15	Status of the SwissFEL Facility at the Paul Scherrer Institute	223
	S. Reiche Paul Scherrer Institut, Villigen, Switzerland
	SwissFEL is a X-ray Free-electron Laser facility with a soft and hard X-ray beamline, planned to be built at the Paul Scherrer Institute and to be finished in 2016. It covers the wavelength range from 1 Angstrom to 7 nm. In addition to the SASE operation at the entire wavelength, seeding is foreseen down to a wavelength of 1 nm. We report in this presentation the status of the SwissFEL facility, including the layout, the timeline of the project, the different operation modes and the expected performance of the FEL beamlines.

TUPA16	A Simple Spectral Calibration Technique for Terahertz Free Electron Laser Radiation	227
	G. Berden FOM Rijnhuizen, Nieuwegein, The Netherlands R.T. Jongma, F.J.P. Wijnen, H.J.F.M. van der Pluijm Radboud University, Nijmegen, The Netherlands
	Upconversion of terahertz FEL radiation to the optical spectral region allows the use of highly efficient optical detection techniques (such as photo-diodes, spectrometers, array detectors) for sensitive characterization of the THz radiation. For online monitoring of the FEL radiation, a small fraction of the radiation is upconverted to the near-infrared region using a ZnTe crystal and a narrow bandwidth continuous wave (cw) laser operating at 780 nm. The ZnTe crystal does not need any angle tuning, and allows the efficient conversion of all wavelengths longer than 100 μm. Because the upconversion laser is cw, the FEL radiation is automatically temporally synchronized. Furthermore, its narrow bandwidth ensures that the spectral properties of the upconverted light can be directly related to the FEL radiation. In this contribution we demonstrate the upconversion technique for the spectral characterization of THz pulses of FELIX. In the near future, the upconversion spectrometer will be used as online wavelength spectrometer for FLARE, the THz FEL under construction at the Radboud University in Nijmegen which will operate in the 100-1500 μm spectral range.

TUPA18	Considerations about Optics-Based Phase-Space Measurements at Linac-Based FEL Facilities	231
	B. Beutner, E. Prat Paul Scherrer Institut, Villigen, Switzerland
	Transverse phase-space measurements are an essential issue for FEL facilities. After acceleration in the injector the energy is sufficiently high to bring the beam out of the space-charge dominated regime, thus optics based techniques are favored. The beam moments at a given point in the machine are fitted to beam size values downstream with different phase advances between the reconstruction and the measurement point. Two principle methods are possible. Beam sizes can be measured at different positions in the beam line keeping the lattice unchanged. The other possibility is to actively change quadrupoles and use only one screen. These two techniques are compared in this paper including monte-carlo studies on systematic errors using the SwissFEL Injector Test Facility as an example. On the other hand beam size measurements, which are done with OTR screens at SwissFEL Injector Test Facility, are critical for such measurements. An analysis of these images can be an issue, especially if the signal-to-noise is compromised for example by low bunch charges. This study on the phase-space measurement techniques will be completed by a discussion of the image post-processing procedures.

TUPA19	Operation Modes and Longitudinal Layout for the SwissFEL Hard X-Ray Facility	235
	B. Beutner, S. Reiche Paul Scherrer Institut, Villigen, Switzerland
	The SwissFEL facility will produce coherent, ultrabright, and ultra-short photon pulses covering a wavelength range from 0.1 nm to 7 nm, requiring an emittance between 0.18 to 0.43 mm mrad at bunch charges between 10pC and 200pC. In nominal operation continous changes between these two bunch charges will be offered to the users in order to allow them an individual tradeoff between photon power and pulse length depending on thier requirements. The facility consists of an S-band rf-gun and booster and a C-band main linac, which accelerates the beam up to 5.8 GeV. Two compression chicanes will provide a nominal peak current of about 1-3 kA depending on the charge. In addition special operation setups for ultra short single mode photon pulses and large bandwidth will be availiable to users. In this paper different operation modes including nominal operation as well as special modes are presented and discussed in terms of photon performance and machine stability requiremnts.

TUPA20	Third Harmonic Lasing in the NIJI-IV Storage Ring Free-Electron Lasers	239
	N. Sei, H. Ogawa, K. Yamada AIST, Tsukuba, Ibaraki, Japan
	Funding: This study was financially supported by the Budget for Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology. Studies of the storage ring free electron lasers (SRFELs) and their application experiments have progressed with the compact storage ring NIJI-IV at the National Institute of Advanced Industrial Science and Technology. We achieved SRFEL oscillations on the third harmonic in the near-infrared region. The measured gain and power of the third-harmonic FEL were consistent with those obtained by the storage ring FEL theory. The measured linewidth of the third-harmonic FEL was less than that of the fundamental FEL, and its pulse width was wider than that of the fundamental FEL. Our studies would be useful for a study of x-ray FEL oscillations with a resonator. In this presentation, characteristics of the higher-harmonic FELs with the NIJI-IV will be discussed in detail. : N. Sei et al., J. Phys. Soc. Jpn. 79 (2010) 093501.

TUPA21	Optical Synchronization of the SwissFEL 250 Mev Test Injector Gun Laser With the Optical Master Oscillator	243
	V.R. Arsov, S. Hunziker, M.G. Kaiser, V. Schlott Paul Scherrer Institut, Villigen, Switzerland F. Löhl CLASSE, Ithaca, New York, USA
	Funding: This work is partly supported by IRUVX-PP, an EU co-funded project under FP7 (Grant Agreement 211285) The SwissFEL gun laser stability is crucial for stable SASE operation in the hard X-ray regime. In 10 pC mode in which sub-10 fs photon pulses will be delivered for the users, the gun laser arrival time jitter at the cathode shouldn't exceed 30 fs (rms). In the present design it is foreseen that the gun oscillator is optically stabilized. It is also necessary to check the stability of the combination laser oscillator and transfer line with an optical reference. For this, the Ti:Sa oscillator was used as a master laser and its pulses were delivered through a ca. 5 m long free space transfer line to optically synchronize an Er-fiber oscillator via two color balanced optical cross correlator with a BBO crystal. The two lasers were placed on different optical tables, which didn't have a mechanical connection through the transfer line. Stable optical lock for at least 60 minutes was demonstrated with an in-loop stability in the range 3.7-17.6 fs. In the range 10 Hz-1 kHz the phase noise stability of the optically locked Er-fiber oscillator varied between 76.5 fs and 118.5 fs rms, 76 fs of which was the contribution of the 1.5 GHz PLO, to which the Ti:Sa oscillator was RF-locked.

TUPA22	FLASH II: A Project Update	247
	B. Faatz, V. Ayvazyan, N. Baboi, V. Balandin, W. Decking, S. Düsterer, H.-J. Eckoldt, M. Felber, J. Feldhaus, N. Golubeva, K. Honkavaara, M. Körfer, T. Laarmann, A. Leuschner, L. Lilje, T. Limberg, D. Nölle, F. Obier, A. Petrov, E. Plönjes, K. Rehlich, H. Schlarb, B. Schmidt, M. Schmitz, S. Schreiber, H. Schulte-Schrepping, J. Spengler, M. Staack, K.I. Tiedtke, M. Tischer, R. Treusch, M. Vogt, H.C. Weddig DESY, Hamburg, Germany J. Bahrdt, R. Follath, K. Holldack, A. Meseck, R. Mitzner HZB, Berlin, Germany J. Chen, H.X. Deng, B. Liu SINAP, Shanghai, People's Republic of China M. Drescher, A. Hage, V. Miltchev, R. Riedel, J. Rönsch-Schulenburg, J. Roßbach, M. Schulz, A. Willner Uni HH, Hamburg, Germany M. Gensch HZDR, Dresden, Germany F. Tavella HIJ, Jena, Germany
	FLASH II is an extension of the existing FLASH facility by an undulator line and an experimental Hall of which the construction will start before the end of the year. Aims are to increase beamtime for users and implement HHG seeding for the longer wavelength range from 10 to 40 nm at a reduced repetition rate of 100 kHz. Additional seeding schemes are under discussion as a future option. We will present a progress report of FLASH II.

TUPA25	EEHG Seeding Design for SwissFEL	251
	E. Prat, S. Reiche Paul Scherrer Institut, Villigen, Switzerland
	The SwissFEL facility, planned at the Paul Scherrer Institute, is based on the SASE operation of a hard (1-7 Å) and a soft (7-70 Å) X-ray FEL beamline. In addition, seeding is foreseen for the soft X-ray beamline, down to a wavelength of 1 nm. The Echo-Enabled Harmonic Generation (EEHG) scheme, which utilizes a rather complex manipulation of the longitudinal phase space distribution of the electron beam to generate high harmonic density modulation, is presently considered the first choice for seeding at SwissFEL. However, EEHG is highly demanding and complex at 1 nm, therefore other strategies like High-Harmonic Generation (HHG) and self-seeding are also evaluated. This paper presents the current status of the seeding design for SwissFEL based on EEHG.

TUPA26	Beam Commissioning of the SACLA Accelerator	255
	T. Hara, H. Tanaka, K. Togawa RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Hasegawa, Y. Kano, T. Morinaga, Y. Tajiri, S. Tanaka, R. Yamamoto SES, Hyogo-pref., Japan
	The commissioning of the X-ray FEL facility of SPring-8, which is named SACLA (SPring-8 Angstrom Compact free-electron LAser), has been started since February 2011. During the beam commissioning, beam diagnostic system and control system are also tested and improved to enable fine tuning of the machine. The position and energy of the electron beam shows excellent stability and the fault rate of the RF system per hour is currently decreased to less than one. Since coherent OTR hinders the beam profile measurement after full bunch compression, several OTR screens are changed to YAG screens with a partial mask installed in its optics. So far the electron beam is successfully accelerated up to 8 GeV and spontaneous emission was observed with weak bunch compression. For the lasing, the RF parameters are first set so that a 0.1 nC bunch is compressed to 30 fs to obtain 3 kA beam current. Then the transverse beam profile is adjusted to match the focusing condition of the undulator section. In the conference, we will report the beam commissioning of the SACLA accelerator.

TUPA30	Multi-stage Bunch Compression at the Japanese X-ray Free Electron Laser SACLA	259
	K. Togawa, T. Hara, H. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	The Japanese x-ray free electron laser facility, named as SACLA (Spring-8 Angstrom Compact free electron LAser), was constructed at SPring-8 site. After finishing installation of all accelerator components, beam commissioning started on February 21, 2011. In order to produce a high-quality electron beam with extremely low-emittance and high-peak current, SACLA adopts multi-stage bunch compression scheme that uses an injector velocity bunching system and following three magnetic bunch compressors. A design bunch compression factor reaches to 3000, namely the peak current of 1 A at the CeB6 thermionic gun increases up to 3 kA at the exit of the final bunch compressor at 1.4 GeV. A longitudinal bunch profile was measured using a transverse beam deflector cavity that was located at the exit of the final bunch compressor. After step-by-step beam commissioning from the injector, we have accomplished a peak current of 3 kA and a short bunch length less than 100 fs. In this conference, we will report the commissioning of the multi-stage bunch compression system at SACLA.

TUPA31	Transverse Phase-space Studies for the Electron Optics at the Direct XUV-seeding Experiment at FLASH (DESY)	263
	S. Ackermann, V. Miltchev, J. Roßbach Uni HH, Hamburg, Germany
	Funding: BMBF under contract No. 05 ES7GU1 - DFG GrK 1355 - Joachim Herz Stiftung During the shutdown in 2009/2010 the Free-Electron Laser in Hamburg (FLASH) was upgraded with an experiment to study the high-gain-FEL amplification of a laser ‘‘seed'' from a high harmonic generation (HHG) source in the XUV wavelength range-sFLASH. For an optimal FEL-performance knowledge of the electron bunch transverse phase-space as well as control on the electron optics parameters is required. In this contribution the technical design, the present status and the commissioning results of the sFLASH diagnostic stations will be presented. The possible options for transverse phase space characterization will be discussed. An emphasis will be put on the error analysis and the tolerance estimations. Analysis of experimental data from both OTR-screens and wire scanners will be presented and discussed.

Paper

Title

Page

Tunable THz-pulse-train Photoinjector

187

Y.-C. Huang, F.H. Chao, C.H. Chen, H.H. Chen, K.Y. Huang
NTHU, Hsinchu, Taiwan

Funding: This work is jointly supported by the National Science Council, under Contract NSC97-2112-M-007-018-MY2; the National Synchrotron Radiation Research Center,under Project 955LRF01N.
A THz-pulse-train photoinjector is under construction at the High-energy OPtics and Electronics (HOPE) Laboratory at National Tsinghua University, Taiwan. This photoinjector is believed to be useful for generating high-power THz radiation, as well as for driving or loading a plasma-wave accelerator. A THz laser beat wave with full tunability in its beat frequency is employed to induce the emission of the THz electron pulses from the photoinjector. We show in our study that such a photoinjector is capable of generating periodically bunched MeV electrons with a bunching factor larger than 0.1 at THz frequencies for a total amount of 1 nC charges in a 10-ps time duration. We will also present a driver laser technology that can tune the electron bunch frequency with ease and help the growth of the high harmonics in the bunching spectrum of accelerated electrons. Experimental progress on this photoinjector will be reported in the conference.

TUPA02

Development of Material Analysis Facility in KU-FEL

190

K. Yoshida, M. A. Bakr, Y.W. Choi, H. Imon, K. Ishida, T. Kii, N. Kimura, R. Kinjo, K. Komai, K. Masuda, H. Ohgaki, M. Omer, S. Shibata, K. Shimahashi, T. Sonobe, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A mid infrared-free electron laser (MIR-FEL) (5-20 μm) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed for contributing to researches on energy science at Institute of Advanced Energy, Kyoto University. Up to now 12-14 μm FEL beam has been generated. When MIR-FEL with the wavelength matched to the molecular vibration mode is irradiated to the material, a particular chemical bond in the material will be selectively excited, or dissociated [1]. The selective photochemical reaction can be applied for surface modification and the evaluation of material in biochemistry, chemistry, and solid physics. Therefore, material analysis facility in combination with MIR-FEL is constructed. In the material analysis facility, advanced analysis systems such as photoluminescence measurement system, photoelectron spectroscopy, super centrifuge and high performance liquids chromatography, ICP emission spectroscopy, and high speed atomic force spectroscopy are installed. In this meeting, the development of material analysis facility will be introduced.
[1] Jhon C.Tully, Science, 312(2006) 1004

TUPA04

sFLASH - Present Status and Commisioning Results

194

V. Miltchev, S. Ackermann, A. Azima, J. Bödewadt, F. Curbis, M. Drescher, E. Hass, Th. Maltezopoulos, M. Mittenzwey, J. Rönsch-Schulenburg, J. Roßbach, R. Tarkeshian
Uni HH, Hamburg, Germany
H. Delsim-Hashemi, K. Honkavaara, T. Laarmann, H. Schlarb, S. Schreiber, M. Tischer
DESY, Hamburg, Germany
R. Ischebeck
Paul Scherrer Institut, Villigen, Switzerland

The free-electron laser in Hamburg (FLASH) was previously being operated in the self-amplified spontaneous emission (SASE) mode, producing photons in the XUV wavelength range. Due to the start-up from noise the SASE-radiation consists of a number of uncorrelated modes, which results in a reduced coherence. One option to simultaneously improve both the coherence and the synchronisation between the FEL-pulse and an external laser is to operate FLASH as an amplifier of a seed produced using high harmonics generation (HHG). An experimental set-up - sFLASH, has been installed to test this concept for the wavelengths below 40 nm. The sFLASH installation took place during the planed FLASH shutdown in the winter of 2009/2010. The technical commissioning, which began in the spring of 2010, has been followed by FEL-characterization and seeded-FEL commissioning in 2011. In this contribution the present status and the sFLASH commissioning results will be discussed.

TUPA06

Seeding Schemes on the French FEL Project LUNEX5

198

C. Evain, F. Briquez, M.-E. Couprie, M. Labat, A. Loulergue
SOLEIL, Gif-sur-Yvette, France
V. Malka
LOA, Palaiseau, France

LUNEX5 is a single pass FEL project producing coherent synchrotron radiation with, in a first step, an electron bunch accelerated in conventional RF cavities up to 300 MeV. It is planned to work in a seeded configuration where the longitudinal coherence of the emitted light is improved and the gain length reduced, compared to the SASE configuration (Self-Amplified Spontaneous Emission). Two seeding schemes are considered: High order Harmonic in Gas seeding and EEHG scheme (Echo Enabled Harmonic Generation). Preliminary simulation results indicate that these two schemes permit to reach the saturation below a wavelength of 7 nm, and with less undulator periods for the EEHG scheme. Finally, the feasibility of plasma acceleration based FEL will also be investigated on this facility.

TUPA07

Study of a Silicon Based XFELO for the European XFEL

202

J. Zemella, D. Novikov, M. Tolkiehn
DESY, Hamburg, Germany
J. Roßbach
Uni HH, Hamburg, Germany
H. Sinn
European XFEL GmbH, Hamburg, Germany

For the European XFEL in Hamburg three different SASE undulators are planed whose radiation output have a high peak brilliance up to 5.4·10³³ photon/s/mm²/mrad²/0.1% BW at wavelengths down to below 5·10^-11 m. The radiation pulses are nearly fully coherent in transverse direction but have a poor longitudinal coherence of about 0.3 fs. Several schemes were developed to get a better longitudinal coherence. In this paper an X-ray Free Electron Laser Oscillator is presented whose radiation output is nearly fully coherent in all directions. In contrast to previous schemes it is based on Silicon crystals rather than Diamond. The use of Silicon has the advantage of the availability of perfect crystals in nearly any size and crystal geometry but with a lower reflectivity and heat conduction than Diamond. To overcome the lower round-trip reflectivity of a Silicon cavity a longer undulator has to be used to get a sufficiently large gain. To reduce the heat load an extremely asymmetric crystal geometry has to be used to enlarge the beam spot on the crystal.

TUPA08

The Control System for CAEP FEL

206

D. Zhang, M. Li, H.B. Wang, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

It describes a control system of CAEP Free Electron Laser (FEL), which is a distributed control system based on EPICS and Visual C++6.0. EPICS is popular in large accelerator laboratories in the world. It is a software toolkit for building process control system for a wide variety of experiment and industrial applications. The software tools in the kit provide independent and expandable modules for system configuration, distributed process control, run-time database, alarm manager, etc. It gives detailed description of the magnet power supply system , beam diagnostic system, including the hardware structure and software design. Other subsystems are also described in the paper. The control system has standard module, interoperability, and repeatability are available. The control system is simple direct, and stable.

TUPA09

LUNEX5: A FEL Project Towards the Fifth Generation in France

208

M.-E. Couprie, C. Benabderrahmane, F. Briquez, J. Daillant, J.-C. Denard, C. Evain, P. Eymard, F. Ferrari, J.-M. Filhol, M. Labat, A. Loulergue, P. Marchand, C. Miron, P. Morin, F. Polack
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
B. Carré
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
N. Delerue, R. Roux, A. Variola
LAL, Orsay, France
G. Lambert, V. Malka, A. Rousse
LOA, Palaiseau, France
J. Lüning
CCPMR, Paris, France

LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short intense and coherent pulses in the soft X rays region (down to 7 nm on the fifth harmonic). It comprises a free electron laser in the seeded configuration (High order Harmonic in Gas seeding and Echo Enable Harmonic Generation) using a conventional linear accelerator of 300 MeV. The FEL beamline including 15 m of in vacuum (potentially cryogenic undulators) of 15 and 30 mm period is designed so as to also accommodate a Laser Wake Field Accelerator (LWFA) ranging from 0.3 to 1 GeV, relying on electron beam parameters produced and accelerated by either the 60 TW laser of LOA or by the 10 PW APOLLON laser of ILE. After the completion and testing of the FEL with the conventional accelerator installed inside the SOLEIL booster inner area, the FEL line can be transported to a LWFA. A laser could alternatively be implemented at SOLEIL for starting testing the principles of a fifth generation light source.

TUPA11

Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II

212

T. Tanikawa
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
M. Adachi, M. Katoh, J. Yamazaki, H. Zen
UVSOR, Okazaki, Japan
M. Hosaka, Y. Taira, N. Yamamoto
Nagoya University, Nagoya, Japan

Light source by using a laser seeding technique are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region, and also in generating CH with variable polarizations in deep UV [1]. In previous conferences, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependencies, and injection laser power dependencies on VUV CHs [2]. This time we have successfully observed saturation on CHs intensities and have found some interesting phenomena, which are the necessary power of injection laser to achieve the saturation of CHG is different in different harmonic orders, and the CH intensity is oscillated in deep saturated regime. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations.
[1] M. Labat, et al., Phys. Rev. Lett. 101 (2008) 164803
[2] T. Tanikawa, et al., Prc. 1st Int. Particle Accelerator Conf., Kyoto, 2010.
[3] T. Tanikawa, et al., Appl. Phys. Express 3 (2010) 122702

TUPA13

Present Status and Future Prospects of Project on Utilizing Coherent Light Sources for User Experiments at UVSOR-II

215

H. Zen, K. Hayashi, S.I. Kimura, E. Nakamura, J. Yamazaki
UVSOR, Okazaki, Japan
M. Adachi, M. Katoh
Sokendai - Okazaki, Okazaki, Aichi, Japan
M. Hosaka, Y. Takashima, N. Yamamoto
Nagoya University, Nagoya, Japan
T. Takahashi
Kyoto University, Research Reactor Institute, Osaka, Japan

Funding: Quantum Beam Technology Program supported by JST/MEXT (Japan)
We have been intensively developing coherent light sources utilizing electron bunches in the storage ring, UVSOR-II, by adding some external components to the ring. After successful generation of coherent synchrotron radiation (CSR) in THz range* and coherent harmonic generation (CHG) in DUV range** by using an intense driving laser, a 5-year new research project named as Quantum Beam Technology Program has been started from FY2008. The project includes introduction of new driving laser system, dedicated undulators and beamlines, and aims at utilizing those coherent radiations for user experiments. The new driving laser system has been installed last year. The undulators and beamlines are now under construction. Installation of those components will be finished before the conference. In the conference, we will report on the present status of system development and future plan of application experiments.
*M. Shimada et al., Japanese Journal of Applied Physics, vol. 46, pp. 7939-7944 (2007).
**M. Labat et al., European Physical Journal D, vol. 44, pp. 187-200 (2007).

TUPA14

Conceptual Layout of a New Short-Pulse Radiation Source at DELTA Based on Echo-Enabled Harmonic Generation

219

R. Molo, M. Bakr, H. Huck, M. Höner, S. Khan, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh
DELTA, Dortmund, Germany

As an upgrade of the present coherent harmonic generation (CHG) source at the DELTA storage ring, the installation of an additional undulator to implement and study the echo-enabled harmonic generation (EEHG) scheme [1] is planned. Compared to the CHG scheme, EEHG allows to produce radiation of shorter wavelengths, thus reaching more relevant absorption edges. In order to avoid dispersive distortions, all undulators should be placed along a straight line. This requires to increase the length of the present straight section by rearranging several magnets and vacuum components as well as a significant modification of the storage ring optics.
[1] G. Stupakov, PRL 102, 074801 (2009)

TUPA15

Status of the SwissFEL Facility at the Paul Scherrer Institute

223

S. Reiche
Paul Scherrer Institut, Villigen, Switzerland

SwissFEL is a X-ray Free-electron Laser facility with a soft and hard X-ray beamline, planned to be built at the Paul Scherrer Institute and to be finished in 2016. It covers the wavelength range from 1 Angstrom to 7 nm. In addition to the SASE operation at the entire wavelength, seeding is foreseen down to a wavelength of 1 nm. We report in this presentation the status of the SwissFEL facility, including the layout, the timeline of the project, the different operation modes and the expected performance of the FEL beamlines.

TUPA16

A Simple Spectral Calibration Technique for Terahertz Free Electron Laser Radiation

227

G. Berden
FOM Rijnhuizen, Nieuwegein, The Netherlands
R.T. Jongma, F.J.P. Wijnen, H.J.F.M. van der Pluijm
Radboud University, Nijmegen, The Netherlands

Upconversion of terahertz FEL radiation to the optical spectral region allows the use of highly efficient optical detection techniques (such as photo-diodes, spectrometers, array detectors) for sensitive characterization of the THz radiation. For online monitoring of the FEL radiation, a small fraction of the radiation is upconverted to the near-infrared region using a ZnTe crystal and a narrow bandwidth continuous wave (cw) laser operating at 780 nm. The ZnTe crystal does not need any angle tuning, and allows the efficient conversion of all wavelengths longer than 100 μm. Because the upconversion laser is cw, the FEL radiation is automatically temporally synchronized. Furthermore, its narrow bandwidth ensures that the spectral properties of the upconverted light can be directly related to the FEL radiation. In this contribution we demonstrate the upconversion technique for the spectral characterization of THz pulses of FELIX. In the near future, the upconversion spectrometer will be used as online wavelength spectrometer for FLARE, the THz FEL under construction at the Radboud University in Nijmegen which will operate in the 100-1500 μm spectral range.

TUPA18

Considerations about Optics-Based Phase-Space Measurements at Linac-Based FEL Facilities

231

B. Beutner, E. Prat
Paul Scherrer Institut, Villigen, Switzerland

Transverse phase-space measurements are an essential issue for FEL facilities. After acceleration in the injector the energy is sufficiently high to bring the beam out of the space-charge dominated regime, thus optics based techniques are favored. The beam moments at a given point in the machine are fitted to beam size values downstream with different phase advances between the reconstruction and the measurement point. Two principle methods are possible. Beam sizes can be measured at different positions in the beam line keeping the lattice unchanged. The other possibility is to actively change quadrupoles and use only one screen. These two techniques are compared in this paper including monte-carlo studies on systematic errors using the SwissFEL Injector Test Facility as an example. On the other hand beam size measurements, which are done with OTR screens at SwissFEL Injector Test Facility, are critical for such measurements. An analysis of these images can be an issue, especially if the signal-to-noise is compromised for example by low bunch charges. This study on the phase-space measurement techniques will be completed by a discussion of the image post-processing procedures.

TUPA19

Operation Modes and Longitudinal Layout for the SwissFEL Hard X-Ray Facility

235

B. Beutner, S. Reiche
Paul Scherrer Institut, Villigen, Switzerland

The SwissFEL facility will produce coherent, ultrabright, and ultra-short photon pulses covering a wavelength range from 0.1 nm to 7 nm, requiring an emittance between 0.18 to 0.43 mm mrad at bunch charges between 10pC and 200pC. In nominal operation continous changes between these two bunch charges will be offered to the users in order to allow them an individual tradeoff between photon power and pulse length depending on thier requirements. The facility consists of an S-band rf-gun and booster and a C-band main linac, which accelerates the beam up to 5.8 GeV. Two compression chicanes will provide a nominal peak current of about 1-3 kA depending on the charge. In addition special operation setups for ultra short single mode photon pulses and large bandwidth will be availiable to users. In this paper different operation modes including nominal operation as well as special modes are presented and discussed in terms of photon performance and machine stability requiremnts.

TUPA20

Third Harmonic Lasing in the NIJI-IV Storage Ring Free-Electron Lasers

239

N. Sei, H. Ogawa, K. Yamada
AIST, Tsukuba, Ibaraki, Japan

Funding: This study was financially supported by the Budget for Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology.
Studies of the storage ring free electron lasers (SRFELs) and their application experiments have progressed with the compact storage ring NIJI-IV at the National Institute of Advanced Industrial Science and Technology. We achieved SRFEL oscillations on the third harmonic in the near-infrared region*. The measured gain and power of the third-harmonic FEL were consistent with those obtained by the storage ring FEL theory. The measured linewidth of the third-harmonic FEL was less than that of the fundamental FEL, and its pulse width was wider than that of the fundamental FEL. Our studies would be useful for a study of x-ray FEL oscillations with a resonator. In this presentation, characteristics of the higher-harmonic FELs with the NIJI-IV will be discussed in detail.
*: N. Sei et al., J. Phys. Soc. Jpn. 79 (2010) 093501.

TUPA21

Optical Synchronization of the SwissFEL 250 Mev Test Injector Gun Laser With the Optical Master Oscillator

243

V.R. Arsov, S. Hunziker, M.G. Kaiser, V. Schlott
Paul Scherrer Institut, Villigen, Switzerland
F. Löhl
CLASSE, Ithaca, New York, USA

Funding: This work is partly supported by IRUVX-PP, an EU co-funded project under FP7 (Grant Agreement 211285)
The SwissFEL gun laser stability is crucial for stable SASE operation in the hard X-ray regime. In 10 pC mode in which sub-10 fs photon pulses will be delivered for the users, the gun laser arrival time jitter at the cathode shouldn't exceed 30 fs (rms). In the present design it is foreseen that the gun oscillator is optically stabilized. It is also necessary to check the stability of the combination laser oscillator and transfer line with an optical reference. For this, the Ti:Sa oscillator was used as a master laser and its pulses were delivered through a ca. 5 m long free space transfer line to optically synchronize an Er-fiber oscillator via two color balanced optical cross correlator with a BBO crystal. The two lasers were placed on different optical tables, which didn't have a mechanical connection through the transfer line. Stable optical lock for at least 60 minutes was demonstrated with an in-loop stability in the range 3.7-17.6 fs. In the range 10 Hz-1 kHz the phase noise stability of the optically locked Er-fiber oscillator varied between 76.5 fs and 118.5 fs rms, 76 fs of which was the contribution of the 1.5 GHz PLO, to which the Ti:Sa oscillator was RF-locked.

TUPA22

FLASH II: A Project Update

247

B. Faatz, V. Ayvazyan, N. Baboi, V. Balandin, W. Decking, S. Düsterer, H.-J. Eckoldt, M. Felber, J. Feldhaus, N. Golubeva, K. Honkavaara, M. Körfer, T. Laarmann, A. Leuschner, L. Lilje, T. Limberg, D. Nölle, F. Obier, A. Petrov, E. Plönjes, K. Rehlich, H. Schlarb, B. Schmidt, M. Schmitz, S. Schreiber, H. Schulte-Schrepping, J. Spengler, M. Staack, K.I. Tiedtke, M. Tischer, R. Treusch, M. Vogt, H.C. Weddig
DESY, Hamburg, Germany
J. Bahrdt, R. Follath, K. Holldack, A. Meseck, R. Mitzner
HZB, Berlin, Germany
J. Chen, H.X. Deng, B. Liu
SINAP, Shanghai, People's Republic of China
M. Drescher, A. Hage, V. Miltchev, R. Riedel, J. Rönsch-Schulenburg, J. Roßbach, M. Schulz, A. Willner
Uni HH, Hamburg, Germany
M. Gensch
HZDR, Dresden, Germany
F. Tavella
HIJ, Jena, Germany

FLASH II is an extension of the existing FLASH facility by an undulator line and an experimental Hall of which the construction will start before the end of the year. Aims are to increase beamtime for users and implement HHG seeding for the longer wavelength range from 10 to 40 nm at a reduced repetition rate of 100 kHz. Additional seeding schemes are under discussion as a future option. We will present a progress report of FLASH II.

TUPA25

EEHG Seeding Design for SwissFEL

251

E. Prat, S. Reiche
Paul Scherrer Institut, Villigen, Switzerland

The SwissFEL facility, planned at the Paul Scherrer Institute, is based on the SASE operation of a hard (1-7 Å) and a soft (7-70 Å) X-ray FEL beamline. In addition, seeding is foreseen for the soft X-ray beamline, down to a wavelength of 1 nm. The Echo-Enabled Harmonic Generation (EEHG) scheme, which utilizes a rather complex manipulation of the longitudinal phase space distribution of the electron beam to generate high harmonic density modulation, is presently considered the first choice for seeding at SwissFEL. However, EEHG is highly demanding and complex at 1 nm, therefore other strategies like High-Harmonic Generation (HHG) and self-seeding are also evaluated. This paper presents the current status of the seeding design for SwissFEL based on EEHG.

TUPA26

Beam Commissioning of the SACLA Accelerator

255

T. Hara, H. Tanaka, K. Togawa
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Hasegawa, Y. Kano, T. Morinaga, Y. Tajiri, S. Tanaka, R. Yamamoto
SES, Hyogo-pref., Japan

The commissioning of the X-ray FEL facility of SPring-8, which is named SACLA (SPring-8 Angstrom Compact free-electron LAser), has been started since February 2011. During the beam commissioning, beam diagnostic system and control system are also tested and improved to enable fine tuning of the machine. The position and energy of the electron beam shows excellent stability and the fault rate of the RF system per hour is currently decreased to less than one. Since coherent OTR hinders the beam profile measurement after full bunch compression, several OTR screens are changed to YAG screens with a partial mask installed in its optics. So far the electron beam is successfully accelerated up to 8 GeV and spontaneous emission was observed with weak bunch compression. For the lasing, the RF parameters are first set so that a 0.1 nC bunch is compressed to 30 fs to obtain 3 kA beam current. Then the transverse beam profile is adjusted to match the focusing condition of the undulator section. In the conference, we will report the beam commissioning of the SACLA accelerator.

TUPA30

Multi-stage Bunch Compression at the Japanese X-ray Free Electron Laser SACLA

259

K. Togawa, T. Hara, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The Japanese x-ray free electron laser facility, named as SACLA (Spring-8 Angstrom Compact free electron LAser), was constructed at SPring-8 site. After finishing installation of all accelerator components, beam commissioning started on February 21, 2011. In order to produce a high-quality electron beam with extremely low-emittance and high-peak current, SACLA adopts multi-stage bunch compression scheme that uses an injector velocity bunching system and following three magnetic bunch compressors. A design bunch compression factor reaches to 3000, namely the peak current of 1 A at the CeB6 thermionic gun increases up to 3 kA at the exit of the final bunch compressor at 1.4 GeV. A longitudinal bunch profile was measured using a transverse beam deflector cavity that was located at the exit of the final bunch compressor. After step-by-step beam commissioning from the injector, we have accomplished a peak current of 3 kA and a short bunch length less than 100 fs. In this conference, we will report the commissioning of the multi-stage bunch compression system at SACLA.

TUPA31

Transverse Phase-space Studies for the Electron Optics at the Direct XUV-seeding Experiment at FLASH (DESY)

263

S. Ackermann, V. Miltchev, J. Roßbach
Uni HH, Hamburg, Germany

Funding: BMBF under contract No. 05 ES7GU1 - DFG GrK 1355 - Joachim Herz Stiftung
During the shutdown in 2009/2010 the Free-Electron Laser in Hamburg (FLASH) was upgraded with an experiment to study the high-gain-FEL amplification of a laser ‘‘seed'' from a high harmonic generation (HHG) source in the XUV wavelength range-sFLASH. For an optimal FEL-performance knowledge of the electron bunch transverse phase-space as well as control on the electron optics parameters is required. In this contribution the technical design, the present status and the commissioning results of the sFLASH diagnostic stations will be presented. The possible options for transverse phase space characterization will be discussed. An emphasis will be put on the error analysis and the tolerance estimations. Analysis of experimental data from both OTR-screens and wire scanners will be presented and discussed.