FEL2012 - List of Authors (Giannessi, L.)

Paper

Title

Page

Nonlinear Harmonic Selection in an FEL Undulator System

69

S. Biedron, L. Giannessi, K. Horovitz, S.V. Milton
CSU, Fort Collins, Colorado, USA

Sandra Biedron1, William Fawley1,2, Luca Giannessi1,2,3, Karen Horovitz1, Stephen Milton1 1Colorado State University, Department of Electrical and Computer Engineering, 1373 Campus Delivery, Fort Collins, Colorado 80523 2 and Sincrotrone Trieste 34149 Basovizza (Trieste) Italy 3and ENEA, C.R. Frascati Via Enrico Fermi, 45 - 00044 Frascati (Roma) Italy The area of harmonic selection in undulator magnets is an important area of free electron laser (FEL) research. Within the undulator section of an FEL system, a wiggling electron beam emits coherent radiation at multiple wavelengths (harmonics), but in some cases the output should only be in the desired region for application purposes. Dispersion sections and unique undulators can be tailored in order to select harmonics and control their power levels. GINGER and PERSEO code were used for simulations. This research will lead to a better understanding of the emission process as well as the interaction of beam density distribution, the frequency and phase relationship of emission, and the amplitude of the emission as a function of time. Furthermore, harmonic control has applications within oscillator or amplifier-based FEL systems.

MOOB06

First Lasing of FERMI FEL-2 (1° Stage) and FERMI FEL-1 Recent Results

13

L. Giannessi, E. Allaria, L. Badano, D. Castronovo, P. Cinquegrana, P. Craievich, G. D'Auria, M.B. Danailov, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, E. Ferrari, L. Fröhlich, G. Gaio, R. Ivanov, E. Karantzoulis, B. Mahieu, N. Mahne, I. Nikolov, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, M. Veronese, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
F. Parmigiani
Università degli Studi di Trieste, Trieste, Italy

The FERMI@Elettra seeded Free Electron Laser (FEL) is based on two complementary FEL lines, FEL-1 and FEL-2. FEL-1 is a single stage cascaded FEL delivering light in the 80-20nm wavelength range, while FEL-2 is a double stage cascaded FEL where the additional stage should extend the frequency up-conversion to the spectral range of 20-4nm. The FEL-1 beam line is in operation since the end of 2010, with user experiments carried on in 2011 and 2012. During 2012 the commissioning of the FEL-2 beam line has started and the first observation of coherent light from the first stage of the cascade has been demonstrated. In the meanwhile the commissioning of a number of key components of FERMI, as the laser heater, the X-Band cavity for the longitudinal phase space linearization and the high energy RF deflector has been completed. The additional control on the longitudinal phase space and a progressive improvement in the machine optics optimization had a significant impact of FEL-1 performances, which has reached the expected specifications. In addition, emission of radiation at very high order conversion factors (up to 29th) has been observed and double stage cascades have been preliminarily tested with the observation of coherent radiation in the water window, up to the 65th harmonic of the seed laser, at about 4 nm.

Slides MOOB06 [6.633 MB]

MOPD58

Commissioning of the FERMI@ELETTRA Laser Heater

177

S. Spampinati, E. Allaria, L. Badano, S. Bassanese, D. Castronovo, M.B. Danailov, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, L. Giannessi, G. Penco, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno, E. Ferrari
University of Nova Gorica, Nova Gorica, Slovenia

The linac of the FERMI seeded free electron laser includes a laser heater to control the longitudinal microbunching instability, which otherwise is expected to degrade the quality of high brightness electron beam sufficiently to reduce the FEL power. The laser heater consists of an short undulator located in a small magnetic chicane through which an external laser pulse enters to the electron beam both temporally and spatially. The resulting interaction within the undulator produces an energy modulation of the electron beam on the scale of the optical wavelength. This modulation together with the effective R52 transport term of the chicane increases the incoherent energy spread (i.e., e-beam heating). We present the first commissioning results of this system and its impact on the electron density and energy distribution and on FEL output quality.

TUOB02

Spectral Characterization of the FERMI Pulses in the Presence of Electron-beam Phase-space Modulations

213

E. Allaria, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, B. Mahieu, G. Penco, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno, S. Spampinati
University of Nova Gorica, Nova Gorica, Slovenia

As a seeded FEL based on a single stage HGHG configuration, FERMI's FEL-1 has produced very narrow bandwidth FEL pulses in the XUV wavelength region relative to those typical of SASE devices. This important feature of seeded FELs relies however upon the capability to produce high quality electron beams and with clean longitudinal phase spaces. As has been predicted previously, the FEL output spectra can be modified from a simple, nearly transform-limited single spike by modulation and distortions of the longitudinal phase space of the electron beam. In this work we report a study of the FEL spectra recorded at FERMI for various situations showing the effects of phase-space modulation on the FEL properties.

Slides TUOB02 [4.376 MB]

WEPD20

Time-Sliced Emittance and Energy Spread Measurements at FERMI@Elettra

417

G. Penco, E. Allaria, P. Craievich, G. De Ninno, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Giannessi, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
S. Spampinati
SLAC, Menlo Park, California, USA

FERMI@Elettra is a single pass seeded FEL based on the high gain harmonic generation scheme, producing intense photon pulses at short wavelengths. For that, a high-brightness electron beam is required, with a small uncorrelated energy spread. In this paper, we present a detailed campaign of measurements aimed at characterizing the electron-beam time-sliced emittance and energy spread, both after the first magnetic compressor and at the end of the linac.

TUPD17

Seeding of SPARC-FEL with a Tunable Fibre-based Source

269

N.Y. Joly
University of Erlangen-Nuremberg, Erlangen-Nuremberg, Germany
S. Bielawski
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
W. Chang, P. Hölzer, K. Mak, P.St.J. Russell, F. Tani, J.C. Travers
Max Planck Institute for the Science of Light, Erlangen, Germany
F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini
ENEA C.R. Frascati, Frascati (Roma), Italy
M.-E. Couprie, M. Labat, T. Tanikawa
SOLEIL, Gif-sur-Yvette, France
G. De Ninno, B. Mahieu
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. Gatti
INFN/LNF, Frascati (Roma), Italy
V. Petrillo
Istituto Nazionale di Fisica Nucleare, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy

Instead of seeding a free electron laser in the UV-VUV with a frequency doubled or tripled laser or high order harmonics, here we investigate and present the first results on seeding SPARC-FEL with a fiber-based tunable ultraviolet source. The seed generation system consists of a kagomé hollow-core photonic crystal fiber filled with noble gas. Diffraction-limited DUV pulses of >50 nJ and fs-duration which are continuously tunable from below 200 nm to above 300 nm are generated. The process is based on soliton-effect self-compression of the pump pulse down to a few optical cycles, accompanied by the emission of a resonant dispersive wave in the DUV spectral region. The quality of the compression highly depends on the pump pulse duration, and ideally, pulses <60 fs should be used. Our experimental set-up and associated GENESIS simulations enable us to study the utility of the seed tunability, and the influence of the seed quality, on the performance of the SPARC-FEL in the 200-300 nm range.

THOC03

Measurement of the Transverse Coherence of the Sase FEL Radiation in The Optical Range Using an Heterodyne Speckle Method

551

M.D. Alaimo, M. Manfredda, M.A.C. Potenza, D. Redoglio
Universita' degli Studi di Milano & INFN, Milano, Italy
M. Artioli, F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, V. Surrenti, A. Torre
ENEA C.R. Frascati, Frascati (Roma), Italy
M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, A. Mostacci
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
V. Petrillo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy

An heterodyne speckle approach has been applied for measuring the transverse coherence of FEL radiation in SASE regime in the optical region (400nm) at SPARC (LNF, Frascati - Italy). It turned out that the coherence length is comparable with the beam size and only slight variations of the coherence properties have been observed after the 5th undulator section. The technique needs a very essential setup composed only by a water suspension of commercial colloidal particles and a CCD camera. The Complex Coherence Factor is retrieved from the Fourier analysis of the interference pattern generated by the stochastic superposition of the almost spherical waves scattered by the particles and the unperturbed transmitted beam (heterodyne speckles). This approach does not require the engineering of ad-hoc devices and provides a two-dimensional map of the transverse coherence without any a-priori assumption about its functional form. The method is suitable for one-shot characterization and it works in the X-ray wavelength as well. It has been previously developed and tested to be effective with synchrotron radiation [*,**] (ID02 and ID06 at ESRF, Grenoble).
* M.D. Alaimo, M.A.C. Potenza, M. Manfredda, G. Geloni, M. Sztucki, T. Narayanan & M. Giglio, Phys. Rev. Lett. 10³ (2009).
** M. Manfredda et al., in preparation

Slides THOC03 [8.489 MB]

FROBI01

Towards Compact Short FEL Sources : Seeding and LWFA based FEL

M. Labat, M.-E. Couprie, A. Loulergue
SOLEIL, Gif-sur-Yvette, France
S. Bielawski
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
G. De Ninno
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
N.Y. Joly
University of Erlangen-Nuremberg, Erlangen-Nuremberg, Germany
P.St.J. Russell
Max Planck Institute for the Science of Light, Erlangen, Germany

The seeding technique, proposed to improve the FEL temporal coherence and to enable more compact schemes, progressed significantly during this last decade. After conventionnal laser sources, eventually doubled or tripled in crystal, high order harmonics generated in gas were successfully used, bringing FELs in the XUV range. We are now involved in the demonstration of a new scheme, using fiber based tunable ultraviolet source. Its output power and tunability are of high interest. Last results obtained with the MaxPlanck Institute and the SPARC teams are presented. Seeding can lead to complex dynamics between the electron and the light pulse. Numerical studies revealed possible pulse splitting effects. We will report on their possible observation in collaboration with the FERMI team. Future FELs may also rely on emerging accelerators generated by laser wakefiled acceleration. Recently, the LUNEX5 project was proposed in France. It consists in one undulator line, fed by either a conventionnal LINAC or a laser wakefield accelerator (LWFA), to deliver XUV fs pulses to pilot user experiments. Preliminary work on radiation optimization of an FEL based on a LWFA will be also presented.

Paper	Title	Page
MOPD10	Nonlinear Harmonic Selection in an FEL Undulator System	69
	S. Biedron, L. Giannessi, K. Horovitz, S.V. Milton CSU, Fort Collins, Colorado, USA
	Sandra Biedron1, William Fawley1,2, Luca Giannessi1,2,3, Karen Horovitz1, Stephen Milton1 1Colorado State University, Department of Electrical and Computer Engineering, 1373 Campus Delivery, Fort Collins, Colorado 80523 2 and Sincrotrone Trieste 34149 Basovizza (Trieste) Italy 3and ENEA, C.R. Frascati Via Enrico Fermi, 45 - 00044 Frascati (Roma) Italy The area of harmonic selection in undulator magnets is an important area of free electron laser (FEL) research. Within the undulator section of an FEL system, a wiggling electron beam emits coherent radiation at multiple wavelengths (harmonics), but in some cases the output should only be in the desired region for application purposes. Dispersion sections and unique undulators can be tailored in order to select harmonics and control their power levels. GINGER and PERSEO code were used for simulations. This research will lead to a better understanding of the emission process as well as the interaction of beam density distribution, the frequency and phase relationship of emission, and the amplitude of the emission as a function of time. Furthermore, harmonic control has applications within oscillator or amplifier-based FEL systems.

MOOB06	First Lasing of FERMI FEL-2 (1° Stage) and FERMI FEL-1 Recent Results	13
	L. Giannessi, E. Allaria, L. Badano, D. Castronovo, P. Cinquegrana, P. Craievich, G. D'Auria, M.B. Danailov, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, E. Ferrari, L. Fröhlich, G. Gaio, R. Ivanov, E. Karantzoulis, B. Mahieu, N. Mahne, I. Nikolov, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, M. Veronese, D. Zangrando, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno University of Nova Gorica, Nova Gorica, Slovenia F. Parmigiani Università degli Studi di Trieste, Trieste, Italy
	The FERMI@Elettra seeded Free Electron Laser (FEL) is based on two complementary FEL lines, FEL-1 and FEL-2. FEL-1 is a single stage cascaded FEL delivering light in the 80-20nm wavelength range, while FEL-2 is a double stage cascaded FEL where the additional stage should extend the frequency up-conversion to the spectral range of 20-4nm. The FEL-1 beam line is in operation since the end of 2010, with user experiments carried on in 2011 and 2012. During 2012 the commissioning of the FEL-2 beam line has started and the first observation of coherent light from the first stage of the cascade has been demonstrated. In the meanwhile the commissioning of a number of key components of FERMI, as the laser heater, the X-Band cavity for the longitudinal phase space linearization and the high energy RF deflector has been completed. The additional control on the longitudinal phase space and a progressive improvement in the machine optics optimization had a significant impact of FEL-1 performances, which has reached the expected specifications. In addition, emission of radiation at very high order conversion factors (up to 29th) has been observed and double stage cascades have been preliminarily tested with the observation of coherent radiation in the water window, up to the 65th harmonic of the seed laser, at about 4 nm.
	Slides MOOB06 [6.633 MB]

MOPD58	Commissioning of the FERMI@ELETTRA Laser Heater	177
	S. Spampinati, E. Allaria, L. Badano, S. Bassanese, D. Castronovo, M.B. Danailov, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, L. Giannessi, G. Penco, C. Spezzani, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno, E. Ferrari University of Nova Gorica, Nova Gorica, Slovenia
	The linac of the FERMI seeded free electron laser includes a laser heater to control the longitudinal microbunching instability, which otherwise is expected to degrade the quality of high brightness electron beam sufficiently to reduce the FEL power. The laser heater consists of an short undulator located in a small magnetic chicane through which an external laser pulse enters to the electron beam both temporally and spatially. The resulting interaction within the undulator produces an energy modulation of the electron beam on the scale of the optical wavelength. This modulation together with the effective R52 transport term of the chicane increases the incoherent energy spread (i.e., e-beam heating). We present the first commissioning results of this system and its impact on the electron density and energy distribution and on FEL output quality.

TUOB02	Spectral Characterization of the FERMI Pulses in the Presence of Electron-beam Phase-space Modulations	213
	E. Allaria, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, B. Mahieu, G. Penco, C. Spezzani, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno, S. Spampinati University of Nova Gorica, Nova Gorica, Slovenia
	As a seeded FEL based on a single stage HGHG configuration, FERMI's FEL-1 has produced very narrow bandwidth FEL pulses in the XUV wavelength region relative to those typical of SASE devices. This important feature of seeded FELs relies however upon the capability to produce high quality electron beams and with clean longitudinal phase spaces. As has been predicted previously, the FEL output spectra can be modified from a simple, nearly transform-limited single spike by modulation and distortions of the longitudinal phase space of the electron beam. In this work we report a study of the FEL spectra recorded at FERMI for various situations showing the effects of phase-space modulation on the FEL properties.
	Slides TUOB02 [4.376 MB]

WEPD20	Time-Sliced Emittance and Energy Spread Measurements at FERMI@Elettra	417
	G. Penco, E. Allaria, P. Craievich, G. De Ninno, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Giannessi, C. Spezzani, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy S. Spampinati SLAC, Menlo Park, California, USA
	FERMI@Elettra is a single pass seeded FEL based on the high gain harmonic generation scheme, producing intense photon pulses at short wavelengths. For that, a high-brightness electron beam is required, with a small uncorrelated energy spread. In this paper, we present a detailed campaign of measurements aimed at characterizing the electron-beam time-sliced emittance and energy spread, both after the first magnetic compressor and at the end of the linac.

TUPD17	Seeding of SPARC-FEL with a Tunable Fibre-based Source	269
	N.Y. Joly University of Erlangen-Nuremberg, Erlangen-Nuremberg, Germany S. Bielawski PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France W. Chang, P. Hölzer, K. Mak, P.St.J. Russell, F. Tani, J.C. Travers Max Planck Institute for the Science of Light, Erlangen, Germany F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini ENEA C.R. Frascati, Frascati (Roma), Italy M.-E. Couprie, M. Labat, T. Tanikawa SOLEIL, Gif-sur-Yvette, France G. De Ninno, B. Mahieu Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. Gatti INFN/LNF, Frascati (Roma), Italy V. Petrillo Istituto Nazionale di Fisica Nucleare, Milano, Italy J.V. Rau ISM-CNR, Rome, Italy
	Instead of seeding a free electron laser in the UV-VUV with a frequency doubled or tripled laser or high order harmonics, here we investigate and present the first results on seeding SPARC-FEL with a fiber-based tunable ultraviolet source. The seed generation system consists of a kagomé hollow-core photonic crystal fiber filled with noble gas. Diffraction-limited DUV pulses of >50 nJ and fs-duration which are continuously tunable from below 200 nm to above 300 nm are generated. The process is based on soliton-effect self-compression of the pump pulse down to a few optical cycles, accompanied by the emission of a resonant dispersive wave in the DUV spectral region. The quality of the compression highly depends on the pump pulse duration, and ideally, pulses <60 fs should be used. Our experimental set-up and associated GENESIS simulations enable us to study the utility of the seed tunability, and the influence of the seed quality, on the performance of the SPARC-FEL in the 200-300 nm range.

THOC03	Measurement of the Transverse Coherence of the Sase FEL Radiation in The Optical Range Using an Heterodyne Speckle Method	551
	M.D. Alaimo, M. Manfredda, M.A.C. Potenza, D. Redoglio Universita' degli Studi di Milano & INFN, Milano, Italy M. Artioli, F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, V. Surrenti, A. Torre ENEA C.R. Frascati, Frascati (Roma), Italy M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, A. Mostacci INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy V. Petrillo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy J.V. Rau ISM-CNR, Rome, Italy
	An heterodyne speckle approach has been applied for measuring the transverse coherence of FEL radiation in SASE regime in the optical region (400nm) at SPARC (LNF, Frascati - Italy). It turned out that the coherence length is comparable with the beam size and only slight variations of the coherence properties have been observed after the 5th undulator section. The technique needs a very essential setup composed only by a water suspension of commercial colloidal particles and a CCD camera. The Complex Coherence Factor is retrieved from the Fourier analysis of the interference pattern generated by the stochastic superposition of the almost spherical waves scattered by the particles and the unperturbed transmitted beam (heterodyne speckles). This approach does not require the engineering of ad-hoc devices and provides a two-dimensional map of the transverse coherence without any a-priori assumption about its functional form. The method is suitable for one-shot characterization and it works in the X-ray wavelength as well. It has been previously developed and tested to be effective with synchrotron radiation [,] (ID02 and ID06 at ESRF, Grenoble). M.D. Alaimo, M.A.C. Potenza, M. Manfredda, G. Geloni, M. Sztucki, T. Narayanan & M. Giglio, Phys. Rev. Lett. 10³ (2009). ** M. Manfredda et al., in preparation
	Slides THOC03 [8.489 MB]

FROBI01	Towards Compact Short FEL Sources : Seeding and LWFA based FEL
	M. Labat, M.-E. Couprie, A. Loulergue SOLEIL, Gif-sur-Yvette, France S. Bielawski PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France G. De Ninno Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy N.Y. Joly University of Erlangen-Nuremberg, Erlangen-Nuremberg, Germany P.St.J. Russell Max Planck Institute for the Science of Light, Erlangen, Germany
	The seeding technique, proposed to improve the FEL temporal coherence and to enable more compact schemes, progressed significantly during this last decade. After conventionnal laser sources, eventually doubled or tripled in crystal, high order harmonics generated in gas were successfully used, bringing FELs in the XUV range. We are now involved in the demonstration of a new scheme, using fiber based tunable ultraviolet source. Its output power and tunability are of high interest. Last results obtained with the MaxPlanck Institute and the SPARC teams are presented. Seeding can lead to complex dynamics between the electron and the light pulse. Numerical studies revealed possible pulse splitting effects. We will report on their possible observation in collaboration with the FERMI team. Future FELs may also rely on emerging accelerators generated by laser wakefiled acceleration. Recently, the LUNEX5 project was proposed in France. It consists in one undulator line, fed by either a conventionnal LINAC or a laser wakefield accelerator (LWFA), to deliver XUV fs pulses to pilot user experiments. Preliminary work on radiation optimization of an FEL based on a LWFA will be also presented.