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

Paper	Title	Page
TUPB04	Status of the FEL User Facility FLASH	267
	S. Schreiber, B. Faatz, J. Feldhaus, K. Honkavaara, R. Treusch, M. Vogt DESY, Hamburg, Germany
	The free-electron laser FLASH at DESY, Germany has been upgraded in 2010 and extended its wavelength range down to 4.1 nm. Beside the increased electron beam energy to 1.25 GeV, an other important upgrade is the installation of 3.9 GHz superconducting RF cavities in the injector. They are used to shape the longitudinal electron beam phase space. Now, significantly more FEL radiation energy per pulse of up to several hundreds of microjoules are achieved. Moreover, the system allows to adjust the FEL pulse length, from long pulses of more than 200 fs to short pulses well below 50 fs. The upgraded FLASH facility shows an excellent performance in terms of FEL radiation quality and stability as well as in reliability of operation. The 3rd user period started as scheduled in September 2010.

TUPB06	Design of Shanghai High Power THz -FEL Source	271
	J.H. Dai, Z.M. Dai, H.X. Deng SINAP, Shanghai, People's Republic of China
	Funding: This work was supported by the CAS (29Y029011) and Shanghai NSF (09JC1416900). An ERL-based THz source with kW average power is proposed in Shanghai, which will serve as an effective tool in material and biological sciences. In this paper, the physical design of two FEL oscillators, in the frequency range of 2~10THz and 0.5~2THz respectively, are given. In the design strategy, three dimensional, time-dependent numerical modelling of GENESIS and paraxial optical propagation code (OPC) are used. The performances of THz oscillator, the detuning effects and the influence of the THz radiation to the electron beam are presented.

TUPB09	Free Electron Lasers in 2011	274
	J. Blau, K. R. Cohn, W.B. Colson, C.M. Pogue, M. Stanton, A.I. Yilmaz NPS, Monterey, California, USA
	Funding: This work has been supported by the Office of Naval Research. Thirty-five years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and discussed.

TUPB10	Echo Seeding Experiment at FLASH	279
	K.E. Hacker, S. Khan DELTA, Dortmund, Germany G. Angelova Hamberg, V.G. Ziemann Uppsala University, Uppsala, Sweden A. Azima Uni HH, Hamburg, Germany P. Salén, P. van der Meulen FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden H. Schlarb DESY, Hamburg, Germany
	Using the two perpendicularly oriented undulators and chicanes developed for an optical replica synthesizer (ORS) experiment together with the sFLASH 800 nm seed laser, radiator undulators and diagnostics, an echo seeding experiment will be conducted at FLASH in January 2012. For this experiment, the 800 nm laser pulse will be transported with a new, 12 meter long, in-vacuum laser transport line. On an in-vacuum optical breadboard, the 800 nm pulse will then be tripled in beta-BBO nonlinear crystals. The laser pulse will then be split longitudinally using a birefringent alpha BBO crystal into two pulses with orthogonal polarization states corresponding to the orthogonal orientations of the ORS undulators. These pulses will be focused to a 400 μm waist between the undulators with a Galileo telescope and steered with 4 motorized mirrors onto the electron beam axis in the ORS undulator section. The hardware layout and simulations of the echo seeding parameters will be described.

TUPB12	Combined Optimization of a Linac-based FEL Light Source Using a Multiobjective Genetic Algorithm	283
	C. F. Papadopoulos, D. Filippetto, G. Penn, J. Qiang, F. Sannibale, M. Venturini LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 We report on the development status and preliminary results of a combined optimization scheme for a linac-based, high repetition rate, soft X-ray FEL. The underlying model includes the injector and linac parts of the machine, and the scheme will integrate the design process of these components toward the optimization of the FEL performance. For this, a parallel, multi-objective genetic algorithm is used. We also discuss the beam dynamics considerations that lead to the choices of objectives, or figure-of-merit beam parameters, and describe numerical solutions compatible with the requirements of a high repetition rate user facility.

TUPB13	Beam Dynamics Considerations for APEX a High Repetition Rate Photoinjector	287
	C. F. Papadopoulos, D. Filippetto, F. Sannibale, R.P. Wells LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 The Advanced Photoinjector EXperiment is a photo-injector project at Lawrence Berkeley National Lab, designed to test the performance of a high repetition rate (>1 MHz) VHF normal conducting electron gun. The requirements of high beam brightness, as well as significant compression at low energy determine the base setup for the injector transport line. The beam dynamics considerations for a high repetition rate injector are discussed and the potential to use multiple bunch charges that require different tunings of the base setup is explored.

TUPB14	Design Studies for Cascaded HGHG and EESHG Experiments Based on SDUV-FEL	291
	C. Feng, J.H. Chen, H.X. Deng, Q. Gu, D. Wang, M. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	Funding: This work was supported by the National Natural Science Foundation of China (Grant No. 10935011). As a test facility for modern FEL R&D, The Shanghai deep ultra-violent FEL (SDUV-FEL) is now under upgrading for the cascading two stage of HGHG experiment. It is found that this upgraded facility will be also well suited for the echo-enabled staged harmonic generation (EESHG) scheme demonstration. With help of 3D simulation codes, design studies on the FEL physics for both these two schemes based on the upgraded SDUV-FEL is presented in this paper.

TUPB18	Preliminary Studies of a Possible Normal-conducting Linac Option for the UK's New Light Sourc	295
	R.P. Walker, C. Christou, J.H. Han Diamond, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom
	A Conceptual Design Report for a major new soft-Xray light source facility for the UK, the New Light Source (NLS), based on high repetition rate free-electron lasers driven by a cw superconducting L-band linac was completed in May 2010. While the science case for such a facility was considered very strong, due to funding restrictions the NLS design project, supported by STFC and Diamond Light Source, was terminated after completion of the CDR. Since then we have been giving some preliminary considerations to a possible alternative option for the NLS which could provide similar performance but at reduced repetition rate, and potentially reduced cost, based on normal conducting technology. In this report we summarise the work done so far, including possible operating parameters and performance, as well as an assessment of relative costs of different frequency options.

TUPB19	Design and Beam Dynamics Simulation for the Photoinjector of Shanghai Soft X-ray Free Electron Laser Test Facility	299
	W.-H. Huang, Q. Du, Y.-C. Du, H.J. Qian, C.-X. Tang, L.X. Yan TUB, Beijing, People's Republic of China
	The Shanghai soft X-ray free electron laser test facility (SXFEL) aims to radiate at 9 nm based on the cascaded high-gain harmonic-generation (HGHG) scheme. The photoinjector of SXFEL consists of Ti-sapphire driving laser system, S-band photocathode RF gun, booster linacs, laser heater, beam diagnostics and matching section. It will produce ~130 MeV electron beam in high charge regime (~0.5 nC) with a baseline transverse emittance of 1.5 mm-mrad. This paper will present basic designs and beam dynamics simulations of SXFEL photoinjector.

TUPB21	Conceptual Design of a High Brightness and Fully Coherent Free Electron Laser in VUV Regime	302
	D. Wang, T. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China X.M. Yang DICP, Dalian, People's Republic of China
	In this paper we propose a new generation light source based on the High Gain Harmonic Generation (HGHG) Free Electron Laser (FEL) for scientific researches. This facility is designed to cover wavelength range from 50 nm to 150 nm with high brightness and full coherence by using the continuously tuning Optical Parametric Amplifier (OPA) seed laser system and variable gap undulators.

TUPB22	THz Pump and X-Ray Probe Development at LCLS	304
	A.S. Fisher, H.A. Durr, J.C. Frisch, M. Fuchs, S. Ghimire, J.J. Goodfellow, A. Lindenberg, H. Loos, M. Petree, D.A. Reis SLAC, Menlo Park, California, USA D.R. Daranciang Stanford University, Stanford, California, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under contract DE-AC02-76SF00515. We report on measurements of broadband, intense, coherent transition radiation at terahertz frequencies, generated as the highly compressed electron bunches in LCLS pass through a thin metal foil. The foil is inserted at 45 degrees to the electron beam, 30 m downstream of the undulator. The THz emission passes downward through a diamond window to an optical table below the beamline. A fully compressed 350-pC bunch produces over 0.5 mJ in a nearly half-cycle pulse of 50 fs FWHM with a spectrum peaking at 10 THz. We estimate a peak field at the focus of over 2.5 GV/m. Electro-optic measurements using a newly installed 20-fs Ti:sapphire oscillator will be presented. We will discuss plans to add a THz pump and x-ray probe setup, in which a thin silicon crystal diffracts FEL light onto the table with adjustable time delay from the THz. This will provide a rapid start to user studies of materials excited by intense single-cycle pulses and will serve as a step toward a THz transport line for LCLS-II.

TUPB28	Considerations for a Light Source Test Facility at Daresbury Laboratory	308
	N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom J.A. Clarke, D.J. Dunning, J.W. McKenzie Cockcroft Institute, Warrington, Cheshire, United Kingdom
	This paper considers design options for a dedicated light source test facility at Daresbury Laboratory in the United Kingdom. The facility layout should be easily configurable to enable exploration of many research themes including: ultrashort pulse generation; seeding and harmonic generation; direct laser/electron beam interactions; compact FELs; high brightness photoinjectors. The strategy is to develop and demonstrate novel concepts and expertise relevant to future generations of FEL-based light sources, significantly shortening the R&D phase of any future light source in the UK.

TUPB29	Status of the FERMI@Elettra Project	312
	M. Svandrlik, E. Allaria, E. Busetto, C. Callegari, D. Cocco, P. Craievich, I. Cudin, G. D'Auria, M.B. Danailov, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, M. Ferianis, R. Gobessi, E. Karantzoulis, M. Kiskinova, M. Lonza, C. Masciovecchio, S. Noè, F. Parmigiani, G. Penco, M. Trovò, A. Vascotto, R. Visintini, M. Zaccaria, D. Zangrando, M. Zangrando ELETTRA, Basovizza, Italy
	FERMI@Elettra is a seeded FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) located next to the third-generation synchrotron light source Elettra in Trieste, Italy. The facility is based on a normal conducting linac and covers the wavelength range with two FEL lines, FEL-1 and FEL-2. A photon distribution and diagnostic system transports the photons from the end of the two FEL lines to three experimental stations. Beneficial occupancy of the new undulator hall and experimental hall was given end of Summer 2010 when also all auxiliary systems were made available. The installation of the machine is now almost completed; commissioning of the linac has started in parallel to the installation activities and now commissioning of FEL-1 is in a well advanced status. The first seeded lasing from FEL-1 was actually observed in December 2010 and first experiments are starting in 2011. In this paper an overview of the facility will be given as well as the general status of installation and commissioning and a perspective into future developments and user programs.

TUPB30	Status of the Fritz Haber Institute THz FEL	315
	W. Schöllkopf, W. Erlebach, S. Gewinner, H. Junkes, A. Liedke, G. Meijer, W.Q. Zhang, G. von Helden FHI, Berlin, Germany H. Bluem, V. Christina, M.D. Cole, J. Ditta, D. Dowell, R. Lange, J.H. Park, J. Rathke, T. Schultheiss, A.M.M. Todd, L.M. Young AES, Princeton, New Jersey, USA S.C. Gottschalk STI, Washington, USA K. Jordan Kevin Jordan PE, Newport News, Virginia, USA U. Lehnert, P. Michel, W. Seidel, R. Wünsch FZD, Dresden, Germany
	The THz FEL at the Fritz Haber Institute (FHI) in Berlin is designed to deliver radiation from 4 to 400 microns. A single-plane-focusing undulator combined with a 5.4 m long cavity is used is the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2 m long cavity with a 1-d waveguide for the optical mode is used for the far-IR. A key aspect of the accelerator performance is low longitudinal emittance, < 50 keV-psec, at 200 pC bunch charge and 50 MeV from a gridded thermionic electron source. We utilize twin accelerating structures separated by a chicane to deliver the required performance over the < 20 - 50 MeV energy range. The first structure operates at near fixed field while the second structure controls the output energy, which, under some conditions, requires running in a decelerating mode. "First Light" is targeted for the centennial of the FHI in October 2011 and we will describe progress in the commissioning of this device. Specifically, the measured performance of the accelerated electron beam will be compared to design simulations and the observed matching of the beam to the mid-IR wiggler will be described.

Paper

Title

Page

Status of the FEL User Facility FLASH

267

S. Schreiber, B. Faatz, J. Feldhaus, K. Honkavaara, R. Treusch, M. Vogt
DESY, Hamburg, Germany

The free-electron laser FLASH at DESY, Germany has been upgraded in 2010 and extended its wavelength range down to 4.1 nm. Beside the increased electron beam energy to 1.25 GeV, an other important upgrade is the installation of 3.9 GHz superconducting RF cavities in the injector. They are used to shape the longitudinal electron beam phase space. Now, significantly more FEL radiation energy per pulse of up to several hundreds of microjoules are achieved. Moreover, the system allows to adjust the FEL pulse length, from long pulses of more than 200 fs to short pulses well below 50 fs. The upgraded FLASH facility shows an excellent performance in terms of FEL radiation quality and stability as well as in reliability of operation. The 3rd user period started as scheduled in September 2010.

TUPB06

Design of Shanghai High Power THz -FEL Source

271

J.H. Dai, Z.M. Dai, H.X. Deng
SINAP, Shanghai, People's Republic of China

Funding: This work was supported by the CAS (29Y029011) and Shanghai NSF (09JC1416900).
An ERL-based THz source with kW average power is proposed in Shanghai, which will serve as an effective tool in material and biological sciences. In this paper, the physical design of two FEL oscillators, in the frequency range of 2~10THz and 0.5~2THz respectively, are given. In the design strategy, three dimensional, time-dependent numerical modelling of GENESIS and paraxial optical propagation code (OPC) are used. The performances of THz oscillator, the detuning effects and the influence of the THz radiation to the electron beam are presented.

TUPB09

Free Electron Lasers in 2011

274

J. Blau, K. R. Cohn, W.B. Colson, C.M. Pogue, M. Stanton, A.I. Yilmaz
NPS, Monterey, California, USA

Funding: This work has been supported by the Office of Naval Research.
Thirty-five years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and discussed.

TUPB10

Echo Seeding Experiment at FLASH

279

K.E. Hacker, S. Khan
DELTA, Dortmund, Germany
G. Angelova Hamberg, V.G. Ziemann
Uppsala University, Uppsala, Sweden
A. Azima
Uni HH, Hamburg, Germany
P. Salén, P. van der Meulen
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
H. Schlarb
DESY, Hamburg, Germany

Using the two perpendicularly oriented undulators and chicanes developed for an optical replica synthesizer (ORS) experiment together with the sFLASH 800 nm seed laser, radiator undulators and diagnostics, an echo seeding experiment will be conducted at FLASH in January 2012. For this experiment, the 800 nm laser pulse will be transported with a new, 12 meter long, in-vacuum laser transport line. On an in-vacuum optical breadboard, the 800 nm pulse will then be tripled in beta-BBO nonlinear crystals. The laser pulse will then be split longitudinally using a birefringent alpha BBO crystal into two pulses with orthogonal polarization states corresponding to the orthogonal orientations of the ORS undulators. These pulses will be focused to a 400 μm waist between the undulators with a Galileo telescope and steered with 4 motorized mirrors onto the electron beam axis in the ORS undulator section. The hardware layout and simulations of the echo seeding parameters will be described.

TUPB12

Combined Optimization of a Linac-based FEL Light Source Using a Multiobjective Genetic Algorithm

283

C. F. Papadopoulos, D. Filippetto, G. Penn, J. Qiang, F. Sannibale, M. Venturini
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
We report on the development status and preliminary results of a combined optimization scheme for a linac-based, high repetition rate, soft X-ray FEL. The underlying model includes the injector and linac parts of the machine, and the scheme will integrate the design process of these components toward the optimization of the FEL performance. For this, a parallel, multi-objective genetic algorithm is used. We also discuss the beam dynamics considerations that lead to the choices of objectives, or figure-of-merit beam parameters, and describe numerical solutions compatible with the requirements of a high repetition rate user facility.

TUPB13

Beam Dynamics Considerations for APEX a High Repetition Rate Photoinjector

287

C. F. Papadopoulos, D. Filippetto, F. Sannibale, R.P. Wells
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The Advanced Photoinjector EXperiment is a photo-injector project at Lawrence Berkeley National Lab, designed to test the performance of a high repetition rate (>1 MHz) VHF normal conducting electron gun. The requirements of high beam brightness, as well as significant compression at low energy determine the base setup for the injector transport line. The beam dynamics considerations for a high repetition rate injector are discussed and the potential to use multiple bunch charges that require different tunings of the base setup is explored.

TUPB14

Design Studies for Cascaded HGHG and EESHG Experiments Based on SDUV-FEL

291

C. Feng, J.H. Chen, H.X. Deng, Q. Gu, D. Wang, M. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Funding: This work was supported by the National Natural Science Foundation of China (Grant No. 10935011).
As a test facility for modern FEL R&D, The Shanghai deep ultra-violent FEL (SDUV-FEL) is now under upgrading for the cascading two stage of HGHG experiment. It is found that this upgraded facility will be also well suited for the echo-enabled staged harmonic generation (EESHG) scheme demonstration. With help of 3D simulation codes, design studies on the FEL physics for both these two schemes based on the upgraded SDUV-FEL is presented in this paper.

TUPB18

Preliminary Studies of a Possible Normal-conducting Linac Option for the UK's New Light Sourc

295

R.P. Walker, C. Christou, J.H. Han
Diamond, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

A Conceptual Design Report for a major new soft-Xray light source facility for the UK, the New Light Source (NLS), based on high repetition rate free-electron lasers driven by a cw superconducting L-band linac was completed in May 2010. While the science case for such a facility was considered very strong, due to funding restrictions the NLS design project, supported by STFC and Diamond Light Source, was terminated after completion of the CDR. Since then we have been giving some preliminary considerations to a possible alternative option for the NLS which could provide similar performance but at reduced repetition rate, and potentially reduced cost, based on normal conducting technology. In this report we summarise the work done so far, including possible operating parameters and performance, as well as an assessment of relative costs of different frequency options.

TUPB19

Design and Beam Dynamics Simulation for the Photoinjector of Shanghai Soft X-ray Free Electron Laser Test Facility

299

W.-H. Huang, Q. Du, Y.-C. Du, H.J. Qian, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China

The Shanghai soft X-ray free electron laser test facility (SXFEL) aims to radiate at 9 nm based on the cascaded high-gain harmonic-generation (HGHG) scheme. The photoinjector of SXFEL consists of Ti-sapphire driving laser system, S-band photocathode RF gun, booster linacs, laser heater, beam diagnostics and matching section. It will produce ~130 MeV electron beam in high charge regime (~0.5 nC) with a baseline transverse emittance of 1.5 mm-mrad. This paper will present basic designs and beam dynamics simulations of SXFEL photoinjector.

TUPB21

Conceptual Design of a High Brightness and Fully Coherent Free Electron Laser in VUV Regime

302

D. Wang, T. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
X.M. Yang
DICP, Dalian, People's Republic of China

In this paper we propose a new generation light source based on the High Gain Harmonic Generation (HGHG) Free Electron Laser (FEL) for scientific researches. This facility is designed to cover wavelength range from 50 nm to 150 nm with high brightness and full coherence by using the continuously tuning Optical Parametric Amplifier (OPA) seed laser system and variable gap undulators.

TUPB22

THz Pump and X-Ray Probe Development at LCLS

304

A.S. Fisher, H.A. Durr, J.C. Frisch, M. Fuchs, S. Ghimire, J.J. Goodfellow, A. Lindenberg, H. Loos, M. Petree, D.A. Reis
SLAC, Menlo Park, California, USA
D.R. Daranciang
Stanford University, Stanford, California, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under contract DE-AC02-76SF00515.
We report on measurements of broadband, intense, coherent transition radiation at terahertz frequencies, generated as the highly compressed electron bunches in LCLS pass through a thin metal foil. The foil is inserted at 45 degrees to the electron beam, 30 m downstream of the undulator. The THz emission passes downward through a diamond window to an optical table below the beamline. A fully compressed 350-pC bunch produces over 0.5 mJ in a nearly half-cycle pulse of 50 fs FWHM with a spectrum peaking at 10 THz. We estimate a peak field at the focus of over 2.5 GV/m. Electro-optic measurements using a newly installed 20-fs Ti:sapphire oscillator will be presented. We will discuss plans to add a THz pump and x-ray probe setup, in which a thin silicon crystal diffracts FEL light onto the table with adjustable time delay from the THz. This will provide a rapid start to user studies of materials excited by intense single-cycle pulses and will serve as a step toward a THz transport line for LCLS-II.

TUPB28

Considerations for a Light Source Test Facility at Daresbury Laboratory

308

N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.A. Clarke, D.J. Dunning, J.W. McKenzie
Cockcroft Institute, Warrington, Cheshire, United Kingdom

This paper considers design options for a dedicated light source test facility at Daresbury Laboratory in the United Kingdom. The facility layout should be easily configurable to enable exploration of many research themes including: ultrashort pulse generation; seeding and harmonic generation; direct laser/electron beam interactions; compact FELs; high brightness photoinjectors. The strategy is to develop and demonstrate novel concepts and expertise relevant to future generations of FEL-based light sources, significantly shortening the R&D phase of any future light source in the UK.

TUPB29

Status of the FERMI@Elettra Project

312

M. Svandrlik, E. Allaria, E. Busetto, C. Callegari, D. Cocco, P. Craievich, I. Cudin, G. D'Auria, M.B. Danailov, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, M. Ferianis, R. Gobessi, E. Karantzoulis, M. Kiskinova, M. Lonza, C. Masciovecchio, S. Noè, F. Parmigiani, G. Penco, M. Trovò, A. Vascotto, R. Visintini, M. Zaccaria, D. Zangrando, M. Zangrando
ELETTRA, Basovizza, Italy

FERMI@Elettra is a seeded FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) located next to the third-generation synchrotron light source Elettra in Trieste, Italy. The facility is based on a normal conducting linac and covers the wavelength range with two FEL lines, FEL-1 and FEL-2. A photon distribution and diagnostic system transports the photons from the end of the two FEL lines to three experimental stations. Beneficial occupancy of the new undulator hall and experimental hall was given end of Summer 2010 when also all auxiliary systems were made available. The installation of the machine is now almost completed; commissioning of the linac has started in parallel to the installation activities and now commissioning of FEL-1 is in a well advanced status. The first seeded lasing from FEL-1 was actually observed in December 2010 and first experiments are starting in 2011. In this paper an overview of the facility will be given as well as the general status of installation and commissioning and a perspective into future developments and user programs.

TUPB30

Status of the Fritz Haber Institute THz FEL

315

W. Schöllkopf, W. Erlebach, S. Gewinner, H. Junkes, A. Liedke, G. Meijer, W.Q. Zhang, G. von Helden
FHI, Berlin, Germany
H. Bluem, V. Christina, M.D. Cole, J. Ditta, D. Dowell, R. Lange, J.H. Park, J. Rathke, T. Schultheiss, A.M.M. Todd, L.M. Young
AES, Princeton, New Jersey, USA
S.C. Gottschalk
STI, Washington, USA
K. Jordan
Kevin Jordan PE, Newport News, Virginia, USA
U. Lehnert, P. Michel, W. Seidel, R. Wünsch
FZD, Dresden, Germany

The THz FEL at the Fritz Haber Institute (FHI) in Berlin is designed to deliver radiation from 4 to 400 microns. A single-plane-focusing undulator combined with a 5.4 m long cavity is used is the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2 m long cavity with a 1-d waveguide for the optical mode is used for the far-IR. A key aspect of the accelerator performance is low longitudinal emittance, < 50 keV-psec, at 200 pC bunch charge and 50 MeV from a gridded thermionic electron source. We utilize twin accelerating structures separated by a chicane to deliver the required performance over the < 20 - 50 MeV energy range. The first structure operates at near fixed field while the second structure controls the output energy, which, under some conditions, requires running in a decelerating mode. "First Light" is targeted for the centennial of the FHI in October 2011 and we will describe progress in the commissioning of this device. Specifically, the measured performance of the accelerated electron beam will be compared to design simulations and the observed matching of the beam to the mid-IR wiggler will be described.