Francesca Curbis
Lund University, MAX IV laboratory, Faculty Member
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Free Electron Laser Study of free carbon clusters / C. Spezzani, E. Allaria, M. Coreno, F. Curbis, B. Diviacco, G. De Ninno, L. Romanzin, S. Tileva, M. Trovò, Matteo Amati, Gero Bongiorno, Cristina Lenardi, Tommaso Mazza, Paolo Milani, TA... more
Free Electron Laser Study of free carbon clusters / C. Spezzani, E. Allaria, M. Coreno, F. Curbis, B. Diviacco, G. De Ninno, L. Romanzin, S. Tileva, M. Trovò, Matteo Amati, Gero Bongiorno, Cristina Lenardi, Tommaso Mazza, Paolo Milani, TA Mostefaoui, Paolo Piseri, ...
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A Soft X-ray free electron laser (FEL) for the MAX IV Laboratory is currently in the design phase and it will use the existing 3 GeV linac. Present stability limits in the RF and the photocathode laser will affect the performance of the... more
A Soft X-ray free electron laser (FEL) for the MAX IV Laboratory is currently in the design phase and it will use the existing 3 GeV linac. Present stability limits in the RF and the photocathode laser will affect the performance of the FEL. One of the critical elements for the design of a FEL is to have an estimation on jitter effects of the accelerator parameters on the X-ray radiation. In this regard, we implemented a start-to-end study using Astra, Elegant and Genesis in order to assess possible variations in pulse energy, photon pulse length and spectral width in the Soft X-ray Laser (SXL) radiation. This investigation provides insights on the final SXL performance variation due to RF and laser related jitter affecting the electron beam.
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We further the studies of the model-based optimization of tapered free-electron lasers presented in a recent publication [Phys. Rev. ST Accel. Beams 18, 040702 (2015)]. Departing from the ideal case, wherein the taper profile is a smooth... more
We further the studies of the model-based optimization of tapered free-electron lasers presented in a recent publication [Phys. Rev. ST Accel. Beams 18, 040702 (2015)]. Departing from the ideal case, wherein the taper profile is a smooth and continuous function, we consider the more realistic case, with individual undulator segments separated by break sections. Using the simulation code GENESIS, we apply our taper optimization method to a case, which closely resembles the FLASH2 facility in Hamburg, Germany. By comparing steady-state and time-dependent simulations, we examine how time-dependent effects alter the optimal taper scenario. From the simulation results, we also deduce that the "traditional" empirical method, whereby the intermediate radiation power is maximized after closing every undulator gap, does not necessarily produce the highest final power at the exit of the undulator line. (Less)
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In a free-electron laser equipped with variable-gap undulator modules, the technique of undulator tapering opens up the possibility to increase the radiation power beyond the initial saturation point, thus enhancing the efficiency of the... more
In a free-electron laser equipped with variable-gap undulator modules, the technique of undulator tapering opens up the possibility to increase the radiation power beyond the initial saturation point, thus enhancing the efficiency of the laser. The effectiveness of the enhancement relies on the proper optimization of the taper profile. In this work, a multidimensional optimization approach is implemented empirically in the x-ray free-electron laser FLASH2. The empirical results are compared with numerical simulations.
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We present a setup for producing and characterizing picosecond ultraviolet laser pulses for use in the MAX IV photocathode electron gun preinjector. Frequency-tripled laser pulses from a commercial laser system are shaped directly in the... more
We present a setup for producing and characterizing picosecond ultraviolet laser pulses for use in the MAX IV photocathode electron gun preinjector. Frequency-tripled laser pulses from a commercial laser system are shaped directly in the ultraviolet domain using a Fourier-domain pulse shaper. The pulses were characterized using a transient grating FROG. We discuss a proposed upgrade of the pulse shaper, as well as its limitations. INTRODUCTION AND MOTIVATION The MAX IV Laboratory is a synchrotron radiation facility. Its two storage rings reach electron energies of 1.5 and 3 GeV. In addition to the rings, the lab operates a short pulse facility [1], while a design study for a soft X-ray free electron laser (FEL) at 1-5nm is currently in progress. Both rings are injected by a full energy linac at 3 GeV [2]. The linac can use either a thermionic or a photocathode gun as a source of electrons, but only the photocathode gun can deliver the short electron bunches required for the short pu...
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The Short Pulse Facility (SPF) of the MAX IV Laboratory in Lund, Sweden features the production of ultrashort, incoherent x-ray pulses. It is driven by a 3-GeV linac and comprises two 5-metre undulator modules. While the SPF is designed... more
The Short Pulse Facility (SPF) of the MAX IV Laboratory in Lund, Sweden features the production of ultrashort, incoherent x-ray pulses. It is driven by a 3-GeV linac and comprises two 5-metre undulator modules. While the SPF is designed for spontaneous radiation, we explore alternative operation modes in which the SPF functions as a simple free-electron laser (FEL). In this article, we characterize two of them in time-dependent numerical simulations. We perform a sensitivity study on the electron beam parameters and examine the technique of single-step tapering.
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A Soft X-ray Laser (SXL) beamline utilising FEL technology is being designed for the Short Pulse Facility (SPF) at the MAX IV Laboratory. A conceptual design study has been started following on the scientific case already prepared in... more
A Soft X-ray Laser (SXL) beamline utilising FEL technology is being designed for the Short Pulse Facility (SPF) at the MAX IV Laboratory. A conceptual design study has been started following on the scientific case already prepared in collaboration between several Swedish Universities and driven by a strong (Swedish) user demand. The baseline goal of the SXL beamline is to generate intense and short pulses in the range 1-5 nm (0.2-1 keV). The system is building on the MAX IV linac system, already today providing 100 fs 3 GeV and pulses compressed to 100 fs for other applications within the SPF. As a special feature we foresee a variety of pump-probe capabilities. INTRODUCTION The Short Pulse Facility (SPF) at the MAX IV laboratory is designed to utilize compressed electron pulses directly from the S-band linear accelerator at energies up to 3 GeV. In this facility (fig. 1) there is at the moment one beamline, FemtoMAX, but there are available “slots” for another 2-3 stations or exper...
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Beam-driven plasma-wakefield acceleration is an acceleration scheme promising accelerating fields of at least two to three orders of magnitude higher than in conventional radiofrequency accelerating structures. The scheme relies on using... more
Beam-driven plasma-wakefield acceleration is an acceleration scheme promising accelerating fields of at least two to three orders of magnitude higher than in conventional radiofrequency accelerating structures. The scheme relies on using a charged particle bunch (driver) to drive a non-linear plasma wake, into which a second bunch (witness) can be injected at an appropriate distance behind the first, yielding a substantial energy gain of the witness bunch particles. This puts very special demands on the machine providing the particle beam. In this article, we use simulations to show that, if driver-witness-bunches can be generated in the photocathode electron gun, the MAX IV Linear Accelerator could be used for plasma-wakefield acceleration. (Less)
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A Soft X-ray Laser project (the SXL) aiming to produce FEL radiation in the range of 1 to 5 nm is currently in a conceptual design phase and a report on the design is expected to be delivered by March 2021. The FEL will be driven by the... more
A Soft X-ray Laser project (the SXL) aiming to produce FEL radiation in the range of 1 to 5 nm is currently in a conceptual design phase and a report on the design is expected to be delivered by March 2021. The FEL will be driven by the existing 3 GeV linac at MAX IV laboratory, which also serves as injector for the two storage rings. The science case has been pushed by a large group of mainly Swedish users and consists of experiments ranging from AMO physics to condensed matter, chemistry and imaging in life science. In this contribution, we will present the current conceptual design of the accelerator and the FEL operation modes together with a general overview of the beamline and experimental station. In particular design options for the FEL will be discussed in conjunction with the features of the electron beam from the MAX IV linac and the connection with the proposed experiments. (Less)
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The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). Recently a conceptual design report for a Soft X-ray Laser (SXL) beamline at the end of the... more
The MAX IV LINAC operates both as a full-energy injector for two electron storage rings, and as a driver for a Short Pulse Facility (SPF). Recently a conceptual design report for a Soft X-ray Laser (SXL) beamline at the end of the existing LINAC was started. For SPF and SXL operation, it is important to characterize beam parameters such as bunch profile, slice energy spread and slice emittance. For these measurements, two 3 m long transverse deflecting RF structures with a matching section are being developed. The structures are operating at S-band and have variable polarizations. When fed via a SLED pulse compressor, the two structures can generate a total integrated deflecting voltage higher than 100 MV which is sufficient for measurements with temporal resolutions down to 1 fs. This paper describes the initial RF design of the deflecting structures. (Less)
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The MAX IV Linac is now in routine operation for injection into two storage rings, and as a high-brightness driver for a Short Pulse Facility (SPF). In short-pulse mode the electron bunch is created in a photo cathode gun and compressed... more
The MAX IV Linac is now in routine operation for injection into two storage rings, and as a high-brightness driver for a Short Pulse Facility (SPF). In short-pulse mode the electron bunch is created in a photo cathode gun and compressed in two double achromat bunch compressors that also linearise longitudinal phase space with the second order transfer matrix element T566. T566 in the compressors canbe tweaked with weak sextupoles located at high dispersion. In this paper we present the current experience from operating the bunch compressors at MAX IV and results from initial measurements of longitudinal phase space using our version of the the zero-crossing method.
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The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF). The linac has also been designed to handle the high demands of an FEL injector. In the... more
The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF). The linac has also been designed to handle the high demands of an FEL injector. In the storage ring injection mode, the linac is operated at 10 Hz with a thermionic RF gun and the electron bunches are kicked out from the linac at either 3 GeV or 1.5 GeV to reach the respective storage ring. For the Short Pulse mode the linac will operate at 100 Hz with a high brightness photo cathode gun. Compression is done in two double achromats with positive R56 and the natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a linearising harmonic cavity. The achromat design for bunch compression produces very short, high peak power electron pulses, while minimizing emittance increase. In this paper we present the MAX IV linac design and th...
The FemtoMAX beamline facilitates studies of the structural dynamics of materials. Such studies are of fundamental importance for key scientific problems related to programming materials using light, enabling new storage media and new... more
The FemtoMAX beamline facilitates studies of the structural dynamics of materials. Such studies are of fundamental importance for key scientific problems related to programming materials using light, enabling new storage media and new manufacturing techniques, obtaining sustainable energy by mimicking photosynthesis, and gleaning insights into chemical and biological functional dynamics. The FemtoMAX beamline utilizes the MAX IV linear accelerator as an electron source. The photon bursts have a pulse length of 100 fs, which is on the timescale of molecular vibrations, and have wavelengths matching interatomic distances (Å). The uniqueness of the beamline has called for special beamline components. This paper presents the beamline design including ultrasensitive X-ray beam-position monitors based on thin Ce:YAG screens, efficient harmonic separators and novel timing tools.
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The MAX IV facility in Lund, Sweden is currently under commissioning. There are two guns in the current MAX IV injector, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. There is a... more
The MAX IV facility in Lund, Sweden is currently under commissioning. There are two guns in the current MAX IV injector, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. There is a possibility of extending the facility to include a Free Electron Laser. To investigate how the beam from the injector can be improved and how to match it to the future requirements for a FEL, the emittance meter from SPARC has been recommissioned at the MAX IV gun test stand. In this paper we report on the progress of this work and results from the first measurements.
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The MAX IV injector design predicts a beam with 100 pC of charge and an emittance lower than 1 mm mrad. The photocathode pre-injector is based on the now close to standard 1.6-cell gun adapted to 2.9985 GHz, in combination with a... more
The MAX IV injector design predicts a beam with 100 pC of charge and an emittance lower than 1 mm mrad. The photocathode pre-injector is based on the now close to standard 1.6-cell gun adapted to 2.9985 GHz, in combination with a Ti:Sapphire laser system. This system reaches the requirements of the injector operation for the SPF, but can be tuned beyond specifications to open up new operation modes. During 2016 and 2017 several aspects where investigated to improve the emittance from the current gun, the goal was to meet the SPF specifications. In this paper we report on the progress, discuss the steps taken leading to a final emittance of ~ 1 mm mrad and beyond.
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The MAX IV facility in Lund, Sweden is currently under commissioning. In the MAX IV injector there are two guns, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. The commissioning of the... more
The MAX IV facility in Lund, Sweden is currently under commissioning. In the MAX IV injector there are two guns, one thermionic gun for storage ring injection and one photocathode gun for the Short Pulse Facility. The commissioning of the injector and the LINAC has been ongoing for the last year and ring commissioning is due to start shortly. In this paper we will present the results from beam performance experiments for the injector at the current stage of commissioning.
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The optical klystron installed on the Elettra storage-ring is normally used as interaction region for an oscillator freeelectron laser, but, removing the optical cavity and using an external seed laser, one obtains an effective scheme for... more
The optical klystron installed on the Elettra storage-ring is normally used as interaction region for an oscillator freeelectron laser, but, removing the optical cavity and using an external seed laser, one obtains an effective scheme for single-pass harmonic generation. In this configuration the high-power external laser is synchronizedwith the electron beam entering the first undulator of the optical klystron. The laser-electron beam interaction produces a spatial partition of electrons in micro-bunches separated by the seed wavelength. The micro-bunching is then exploited in the second undulator to produce coherent light at the harmonics of the seed wavelength. The Elettra radiator is an APPLE type undulator and this allows to explore different configurations of polarization. We present here numerical results obtained using the code Medusa for both planar and helical configurations. We also draw a comparison with predictions of the numerical code Genesis.
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The 3GeV linac for the MAX IV laboratory is currently under construction in Lund (Sweden). As full energy injector for the MAX IV rings, a thermionic gun will be used to create electrons. However a photocathode gun planned for a short... more
The 3GeV linac for the MAX IV laboratory is currently under construction in Lund (Sweden). As full energy injector for the MAX IV rings, a thermionic gun will be used to create electrons. However a photocathode gun planned for a short pulse facility will deliver small emittance and ultra-short electron bunches that will be suitable to also drive a Free-Electron Laser. Moreover extending the linac energy with 1 or 2GeV will give the opportunity to get closer to 1 ˚ A radiation with much more flexibility and better performances. Given these opportunities at the MAX IV laboratory, a free electron laser is envisaged in the long term perspective of the facility. In this study we investigate the case of a 5GeV machine which can produce radiation in the X-ray region. The FEL design will benefit from the implementation of self-seeding, to enhance stability of the central wavelength and spectral bandwidth. Tapering along variable gap undulators will help to extract the maximum photon flux an...
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The installation of the test FEL at MAX-lab has recently been completed. The system will be seeded by a tripled Ti:Sapphire laser (263 nm) synchronized to the RF system and the gun laser. Issues important for the seeding will be... more
The installation of the test FEL at MAX-lab has recently been completed. The system will be seeded by a tripled Ti:Sapphire laser (263 nm) synchronized to the RF system and the gun laser. Issues important for the seeding will be presented, ranging from the laser system via the layout of photon and electron optics to timing/synchronization and the theoretical approach.
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The sFLASH project at DESY is an experiment to study direct seeding using a source based on the high-harmonic generation (HHG) process. In contrast to SASE, a seeded FEL exhibits greatly improved longitudinal coherence and higher... more
The sFLASH project at DESY is an experiment to study direct seeding using a source based on the high-harmonic generation (HHG) process. In contrast to SASE, a seeded FEL exhibits greatly improved longitudinal coherence and higher shot-to-shot stability (both spectral and energetic). In addition, the output of the seeded FEL is intrinsically synchronized to the HHG drive laser, thus enabling pump-probe experiments with a resolution of the order of 10 fs. The installation and successful commissioning of the sFLASH components in 2010/2011 has been followed by a planned upgrade in autumn 2011. As a result of these improvements, in spring 2012 direct HHG seeding at 38 nm has been successfully demonstrated. In this contribution, we describe the experimental layout and announce the first seeding at 38 nm. (Less)
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The sFLASH-experiment has been built at the Free- Electron Laser in Hamburg (FLASH) to study the highgain- FEL amplification of a laser seed from a high harmonic generation (HHG) source. Ideally, the HHG seed can be amplified up to a... more
The sFLASH-experiment has been built at the Free- Electron Laser in Hamburg (FLASH) to study the highgain- FEL amplification of a laser seed from a high harmonic generation (HHG) source. Ideally, the HHG seed can be amplified up to a GW-power level, improving both the shot-to-shot stability and the longitudinal coherence of the FEL-pulse. In 2010/2011 the sFLASH-components and sub-systems have been fully installed and commissioned within about 300 hours FLASH beam time dedicated to the seeding project. Procedures to achieve a full six-dimensional overlap between the seed and the electron bunch have been developed and tested. An important milestone reached in the commissioning period is the sFLASH-SASE lasing mode, which was being achieved on a regular basis. A step forward towards the next milestone - The direct seeding in the XUV-wavelength range - is the sFLASH-upgrade during the planed FLASH-shutdown in autumn 2011. In this contribution the main commissioning results and highligh...
Research Interests: Engineering and Physics
A Soft X-ray FEL (the SXL) is currently being designed at the MAX IV Laboratory. In the work to adapt the FEL to the scientific cases several advanced options are being studied for coherence enhancement, generation of short pulses and... more
A Soft X-ray FEL (the SXL) is currently being designed at the MAX IV Laboratory. In the work to adapt the FEL to the scientific cases several advanced options are being studied for coherence enhancement, generation of short pulses and two-color pulses. We will discuss the current status and initial results of the schemes studied, especially regarding the FEL performance with the features of the MAX IV linac, including a positive energy chirp.
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Ultra-short electron pulses suffer from transverse wake fields resulting in a degradation of the beam quality. Since transverse emittance is a crucial parameter for FEL drivers, a careful characterization of wakefields is necessary in the... more
Ultra-short electron pulses suffer from transverse wake fields resulting in a degradation of the beam quality. Since transverse emittance is a crucial parameter for FEL drivers, a careful characterization of wakefields is necessary in the design and commissioning phase of a high-brightness linear accelerator. In thispaperwe investigatethe effectoftransversewakefields in the MAX IV linac. Estimations of the wakepotentials have been done with 2D modeling of the accelerating structures as well as with analytical models. In addition, electron beam effects caused by transverse wakes were studied at FERMI@Elettra [1] to verify the accuracy of the corresponding wakefield model in elegant [2].
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The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (phase 2) [1]. Compression is done in two double achromats with positive... more
The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (phase 2) [1]. Compression is done in two double achromats with positive R56. The natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a harmonic cavity for linearisation of longitudinal phase space. In this proceeding we present results from particle tracking through the MAX IV linac in high brightness mode. We also investigate emittance dilution due to CSR, in the achromat compressors, and transverse wakefields in a high beta function lattice. From the light-source point of view, we present preliminary simulation of the expected spontaneous emission in the x-ray range of the SPF electron beam.
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The linear accelerator at MAX IV was constructed for injection and top-up to the two storage rings and as a high brightness driver for the Short Pulse Facility. It is also prepared to be used as an injector for a possible future Free... more
The linear accelerator at MAX IV was constructed for injection and top-up to the two storage rings and as a high brightness driver for the Short Pulse Facility. It is also prepared to be used as an injector for a possible future Free Electron Laser. Installations were completed and beam commissioning started in the early fall of 2014. In this paper we present the progress during the first phase of commissioning along with results from initial measurements of optics, emittance, beam energy and charge. BACKGROUND The MAX IV facility [1] is the successor of the MAX-lab accelerators at Lund University and includes two storage rings, a full energy linac and a Short Pulse Facility (SPF). The rings will be operated at 1.5 and 3 GeV. The SPF will be a single pass spontaneous linac lightsource, producing subps spontaneous X-ray pulses. The injector will be flexible enough to drive both injection and top-up for the storage rings, and produce high brightness pulses for the SPF. The long term s...
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The MAX IV facility in Lund, Sweden consists of two storage rings for production of synchrotron radiation, and a short-pulse-facility (SPF). The two rings are designed for 3 GeV and 1.5 GeV, respectively, where the initial beam... more
The MAX IV facility in Lund, Sweden consists of two storage rings for production of synchrotron radiation, and a short-pulse-facility (SPF). The two rings are designed for 3 GeV and 1.5 GeV, respectively, where the initial beam commissioning of the former has recently been completed, and commissioning of the latter was started in September 2016. Both rings will be operating with top-up injections delivered by a full-energy injector. In order to reduce losses of high-energy electrons along the injector and in the rings during injection, only electrons that are within a time structure where they can be accumulated in the ring buckets are accelerated. Electrons outside this time structure are dumped before they reach the first LINAC structure by a chopper system. The performance of the chopper system during commissioning of the 3 GeV ring is presented in this paper.
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The test-FEL at MAX-lab is a development set-up for seeding techniques. After the successful demonstration of coherent harmonic generation from a conventional laser, the new layout now presents a gas target for generation of harmonics.... more
The test-FEL at MAX-lab is a development set-up for seeding techniques. After the successful demonstration of coherent harmonic generation from a conventional laser, the new layout now presents a gas target for generation of harmonics. The drive laser will be up-converted and the low harmonics (around 100nm) will seed the electron beam. The energy modulated electrons will then be bunchedin thedispersivesection andwill radiateinthe second undulator. We will detect the second harmonic of the HHG radiation around 50nm. This experiment has several challenges never tried before: co-propagation of the electron beam and the drive laser, interaction of the electron beam with the gas in the target, no-focusingof the harmonics and no drive laser removal. The commissioning will show if this kind of in-line chamber has advantages with respect to more traditional approaches with optical beam transport. The results are relevant for many facilities that are planning to implement HHG seeding in the...
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The design of the pre-injector, including the new gun, for the SXL project [1] is being finalised for the desired modes of operation, 100 pC and 10 pC with short bunches. The photocathode gun is currently being manufactured and... more
The design of the pre-injector, including the new gun, for the SXL project [1] is being finalised for the desired modes of operation, 100 pC and 10 pC with short bunches. The photocathode gun is currently being manufactured and experiments in the MAX IV guntest facility are under preparation to verify the design. In this paper we present the design of the gun and the pre-injector and show some results from simulations using MOGA indicating an emittance less than 0.3 mm mrad.
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The test-FEL at MAX-lab already demonstrated seeded coherent harmonic generation down to 40 nm [1]. As a step further in the development of our seeding techniques, we plan to use a gas target to generate harmonics of the drive laser and... more
The test-FEL at MAX-lab already demonstrated seeded coherent harmonic generation down to 40 nm [1]. As a step further in the development of our seeding techniques, we plan to use a gas target to generate harmonics of the drive laser and seed the electron beam with them. In order to optimize the injection process, our aim is to place the gas target for harmonic generation as close as possible to the first undulator. In order to minimize the losses the transport of the drive laser is done with a minimal number of mirrors and there are neither focusing nor filtering elements between the harmonic chamber and the first undulator. The goal is to test whether the harmonic intensity in the undulator is high enough to induce full energy modulation of the electron beam. The wavelength range of the harmonics that will be used as seed is around 100 nm and we plan to detect the coherent harmonic signal of the second harmonic generated in the radiator. The flexibility of the setup will allow us t...
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There is an increasing demand from the user community for high quality FEL radiation. The spectrum of this radiation can prove to be a useful tool in characterizing the FEL process. Starting from a tool initially developed at FERMI we... more
There is an increasing demand from the user community for high quality FEL radiation. The spectrum of this radiation can prove to be a useful tool in characterizing the FEL process. Starting from a tool initially developed at FERMI we extend its capabilities to be able to analyze the modal components of the FEL spectrum. In this paper we will describe and compare two different figures of merit and offer initial bench-marking with respect to classic figure of merit for spectra such as FWHM and RMS.
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It is well known that the few X-ray FELs around the world are severely overbooked by users. Having a medium energy linac, such as the one now being installed at the MAX IV laboratory, it becomes natural to think about slightly increasing... more
It is well known that the few X-ray FELs around the world are severely overbooked by users. Having a medium energy linac, such as the one now being installed at the MAX IV laboratory, it becomes natural to think about slightly increasing the electron energy to drive an X-ray FEL. This development is now included in the long term strategic plan for the MAX IV laboratory. We will present the current FEL studies based on an extension of the MAX IV linac to 5GeV to reach the ˚ Angstrom region. The injector for the MAX IV accelerator complex is also equipped with a photocathode gun, capable of producing low emittance electronbeam. Thebunchcompressionandlinearization of the beam is taken care by two double achromats. The basic FEL layout would consist of short period undulators with tapering for extracting all the power from the electron beam. Self-seeding is considered as an option for increasing the spectral and intensity stability.
The installation of the MAX IV linear accelerator is in full progress, and commissioning is planned to start in the second quarter of 2014. The 3 GeV linac will be used as a full energy injector for the two storage rings, and as a high... more
The installation of the MAX IV linear accelerator is in full progress, and commissioning is planned to start in the second quarter of 2014. The 3 GeV linac will be used as a full energy injector for the two storage rings, and as a high brightness driver for a Short Pulse linac light source. The linac has been deigned to also handle the high demands of an FEL injector. The long term strategic plan for the MAX IV laboratory includes an extension of the linac to 5 GeV and an X-ray FEL. In this paper we present the both design concept and status of the MAX IV linac along with parameters of the 3 GeV high quality electron pulses. We also present the first design and simulation results of the upgrade to a 5 GeV X-ray FEL driver
The output power of a free-electron laser (FEL) can be greatly enhanced by tapering the undulator line. In this work, a sensitivity study of a tapered FEL is presented. The study is conducted using the numerical simulation code GENESIS... more
The output power of a free-electron laser (FEL) can be greatly enhanced by tapering the undulator line. In this work, a sensitivity study of a tapered FEL is presented. The study is conducted using the numerical simulation code GENESIS and a taper optimization method. Starting from a possible case for the future X-ray FEL at the MAX IV Laboratory in Lund, Sweden, a number of parameters are varied systematically and the impact on the FEL power is investigated. These parameters include the electron beam's initial energy, current, emittance, energy spread, as well as the seed radiation power.
A motivation for the development of a versatile, programmable source of shaped picosecond pulses for use in photocathode electron gun preinjectors is presented. We present the experimental setup for arbitrary longitudinal pusle shaping of... more
A motivation for the development of a versatile, programmable source of shaped picosecond pulses for use in photocathode electron gun preinjectors is presented. We present the experimental setup for arbitrary longitudinal pusle shaping of the MAX IV photocathode gun laser. The setup consists of a grating-based Fourier-domain shaper capable of stretching the pulses directly in the UV domain. Preliminary results are presented and discussed. INTRODUCTION AND MOTIVATION The MAX IV Laboratory is a facility for production of synchrotron radiation. It includes two storage rings, which operate at electron energies of 1.5 and 3GeV. The facility operates a short pulse facility, while plans to build a soft X-ray Free Electron Laser (FEL) are at an initial stage. Both rings, the Short Pulse Facility (SPF) [1], and the possible future FEL make use of a 3GeV LINAC [2] for injection. There are two preinjectors at the LINAC, a thermionic and a photocathode electron gun. While either of the guns can...
The need of coherent and intense pulsed radiation is spread among many research disciplines, such as biology, nanotechnology, physics, chemistry and medicine. The synchrotron light from traditional sources only partially meets these... more
The need of coherent and intense pulsed radiation is spread among many research disciplines, such as biology, nanotechnology, physics, chemistry and medicine. The synchrotron light from traditional sources only partially meets these characteristics. A new kind of light source has been conceived and developed in the last decades: the Free-Electron Laser (FEL). The FEL process relies on the interaction between a relativistic electron beam and an electromagnetic wave in presence of a static and periodic magnetic field, produced by a device called undulator. This interaction generates coherent radiation at a fundamental frequency and its higher harmonics. In the standard configuration, the electron beam is generated by a linear accelerator and the interaction occurs in a single passage through one or several undulators. An alternative configuration can be obtained if the electrons are supplied by a storage ring. This work has been carried out at the Elettra laboratory within the “new li...
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The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running... more
The MAXIV injector has two guns - a thermionic used for ring injections, and a photocathode used for short pulse facility operation. A commercial Ti:sapphire laser from KMLabs drives the copper based photocathode gun. It has been running without major issues for more than 3 years. The laser delivers up to §I{500}{\textmu J} on the cathode at the third harmonic, §I{263}{nm}, via a vacuum laser transport system. To achieve the desired pulse duration of 2–§I10{ps} the laser pulses, originally ~§I{100}{fs} long, are stretched with a prism pair and the resulting §I{1.5}{ps} pulses stacked by a series of birefringent \textalpha -BBO crystals. Diagnostics consist of photodiodes, spectrometers, and cameras. Longitudinal pulse characterization is done with a cross correlator and a UV FROG.
Thanks to an intensive technological effort in the framework of the EUFELE collaboration, the European FEL at ELETTRA was able to break the previous record for the shortest wavelength of an FEL oscillator. Novel solutions were adopted for... more
Thanks to an intensive technological effort in the framework of the EUFELE collaboration, the European FEL at ELETTRA was able to break the previous record for the shortest wavelength of an FEL oscillator. Novel solutions were adopted for multilayer mirrors to allow FEL operation in the wavelength region between 160 and 190 nm, which is one of the main targets of the project. The characteristics of the FEL pulses measured at 176 nm (spectral profiles, high intensity, meV bandpass, MHz repetition rate) make it a competitive light source for spectroscopy, in particular for fluorescence and Raman studies in the VUV spectral range. Proof of principle experiments have been performed on different types of silica glasses, yielding information on the mechanisms of light absorption in this material. (Less)
sFLASH is a seeded experiment at the Free-Electron Laser FLASH in Hamburg. It uses a 38 nm HighHarmonic-Generation (HHG) scheme to seed the FELprocess in a 10 m long variable-gap undulator. The temporal overlap between the electron and... more
sFLASH is a seeded experiment at the Free-Electron Laser FLASH in Hamburg. It uses a 38 nm HighHarmonic-Generation (HHG) scheme to seed the FELprocess in a 10 m long variable-gap undulator. The temporal overlap between the electron and HHG pulses is critical to the seeding process. The use of a 3 rd harmonic accelerating module provides a high current electron beam with ∼400 fs bunch duration. The duration of the HHG laser pulse is ∼20 fs. The desired overlap is achieved in two steps. Firstly, the HHG drive laser is synchronized to the incoherent spontaneous radiation from an upstream undulator with picosecond resolution. Next, the coherent radiation from an undulator is used to determine the exact overlap of the electron beam in a modulator-radiator set-up.
A Soft X-ray FEL (the SXL) using the existing 3 GeV linac at the MAX IV Laboratory is currently in the design phase. In this contribution, start-to-end simulations, including the photo-injector simulations using ASTRA, the linac... more
A Soft X-ray FEL (the SXL) using the existing 3 GeV linac at the MAX IV Laboratory is currently in the design phase. In this contribution, start-to-end simulations, including the photo-injector simulations using ASTRA, the linac simulations using ELEGANT and the FEL simulations using GENESIS, are presented for 100 pC and 10 pC operation modes. The features of the electron beam from the MAX IV linac and their impact on the FEL performance are discussed.
In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the resonator wavelength can be naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in singlepass linac-based... more
In a storage-ring free-electron laser (FEL), the onset and growth of intra-cavity power at the resonator wavelength can be naturally accompanied by coherent emission at higher harmonics. Contrary to what happens in singlepass linac-based devices, the electron beam is re-circulated in the storage ring and, while the microbunching becomes "thermalized" from turn to turn, the evolution of other bunch properties has to be considered. As a consequence, a correct theoretical understanding of the process requires a proper modeling of turn-by-turn evolution of the electronbeam phase-space, both inside the undulators, where the FEL interaction takes place, and along the ring. To simulate this process we have coupled a modified version of the 3D numerical code Ginger, which models the FEL interaction, together with a linear one-turn map, which propagates the electron beam along the ring. We present our results and a first benchmarking with experiments carried out using the Elettra s...