Generation of ultra-short, high brightness electron beams for single-spike SASE FEL operation

Rosenzweig, James; Alesini, D.; Andonian, G.; Boscolo, M.; Dunning, M.; Faillace, L.; Ferrario, M.; Fukusawa, A.; Giannessi, L.; Hemsing, E.; Marcus, Gabriel; Marinelli, Agostino; Musumeci, P.; O’Shea, Brendan; Palumbo, L.; Pellegrini, C.; Petrillo, V.; Reiche, S.; Ronsivalle, C.; Spataro, B.; Vaccarezza, C.

doi:10.1016/j.nima.2008.04.083

Cited by 92 publications

(51 citation statements)

References 19 publications

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“…High brightness electron beam sources play a fundamental role in high-gain free-electron lasers (FEL) development as well as for linear colliders designed to study the electron-positron collisions [1,2]. For example, the SPARC project of INFN for generating 500 nm of wavelength has required laser-driven rf photocathode guns capable of producing 1 nC bunches of a few picosecond duration with about 1 mm-mrad of emittance [3,4].…”

Section: Introductionmentioning

confidence: 99%

Highlights on photocathodes based on thin films prepared by pulsed laser deposition

Lorusso

Gontad

Perrone

et al. 2011

Phys. Rev. ST Accel. Beams

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We review the current status of metallic photocathodes based on thin films prepared by pulsed laser deposition (PLD) and we explore ways to improve the performance of these devices. PLD seems to be a very efficient and suitable technique for producing adherent and uniform thin films. Time-resolved mass spectrometric investigations definitively suggest that the deposition of high-purity metallic thin films should be carried out in ultrahigh vacuum systems and after a deep and careful laser cleaning of the target surface. Moreover, the laser cleaning of the target surface is highly recommended not only to remove the first contaminated layers but also to improve the quality of the vacuum by reducing the partial pressure of reactive chemical species as H 2 O, H 2 , and O 2 molecules. The challenge to realize high-purity Mg and Y thin films is very interesting for the photocathode R&D due to the good photoemission properties of these metals. Photocathodes based on Mg and Y thin films have been characterized by scanning electron microscopy and x-ray diffraction techniques to derive the morphological and structural features, respectively. They were also tested in a photodiode cell to deduce the photoelectron properties. The quantum efficiency of such photocathodes was systematically improved by in situ laser cleaning treatments of the surface in order to remove the contaminated layers reaching, in this way, the quantum efficiency of the corresponding bulk materials.

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Section: Introductionmentioning

confidence: 99%

Highlights on photocathodes based on thin films prepared by pulsed laser deposition

Lorusso

Gontad

Perrone

et al. 2011

Phys. Rev. ST Accel. Beams

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“…Several techniques have been explored to increase longitudinal coherence, stability, and/or to shorten the FEL pulse time scale towards the attosecond domain. The amplification of one single SASE spike has been demonstrated by compressing the electron beam close or below the FEL coherence length [15,16], by using a chirped bunch energy combined with a matched undulator taper [17][18][19], or by spoiling the whole electron beam except a limited fraction [20,21], a technique that has also been implemented to produce double pulse two-color radiation for pump and probe experiments [22]. Short single or multiple pulses have also been produced in seeded or cascaded FELs [23][24][25][26][27], with increased coherence and shot to shot stability.…”

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confidence: 99%

Observation of Time-Domain Modulation of Free-Electron-Laser Pulses by Multipeaked Electron-Energy Spectrum

et al. 2013

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We present the experimental demonstration of a new scheme for the generation of ultrashort pulse trains based on free-electron-laser (FEL) emission from a multipeaked electron energy distribution. Two electron beamlets with energy difference larger than the FEL parameter have been generated by illuminating the cathode with two ps-spaced laser pulses, followed by a rotation of the longitudinal phase space by velocity bunching in the linac. The resulting self-amplified spontaneous emission FEL radiation, measured through frequency-resolved optical gating diagnostics, reveals a double-peaked spectrum and a temporally modulated pulse structure. DOI: 10.1103/PhysRevLett.111.114802 PACS numbers: 41.60.Cr, 42.55.Àf, 42.65.Ky Radiation pulses with attosecond to femtosecond time scales represent a real possibility for a breakthrough in science and technology, permitting unprecedented insights into the ultrafast electron and nuclear dynamics [1][2][3]. The time-resolved study of electron rearrangements could lead to significant advances in the understanding of intermolecular processes, chemical bond breaking and formation, and the interaction of photoactivated molecules with their environment.Trains of ultrashort radiation pulses enable stroboscopic electron imaging [4] and the investigation of the response accompanying collective electron motion in nanomaterials [5]. They also find further applications in other technical fields, such as the enhancement of transmission or reflectivity in materials, resonant inelastic x-ray scattering, or the ab initio phasing of nanocrystals [6].Sequences of spikes have been synthesized by means of the high harmonic generation driven by lasers in gases [7] and regularly used in experiments [4,8], but are severely limited in efficiency approaching the keV range.Free-electron lasers (FELs) are capable of producing high brightness pulses in the x-ray spectral region [9][10][11][12]. The FEL, in the self-amplified spontaneous emission (SASE) mode of operation [13], generates radiation with limited temporal coherence [14], time duration of the order of the electron bunch length and structured in a chaotic succession of random peaks. The typical time scale of these radiation spikes is set by the FEL Pierce parameter [13]. Several techniques have been explored to increase longitudinal coherence, stability, and/or to shorten the FEL pulse time scale towards the attosecond domain. The amplification of one single SASE spike has been demonstrated by compressing the electron beam close or below the FEL coherence length [15,16], by using a chirped bunch energy combined with a matched undulator taper [17][18][19], or by spoiling the whole electron beam except a limited fraction [20,21], a technique that has also been implemented to produce double pulse two-color radiation for pump and probe experiments [22]. Short single or multiple pulses have also been produced in seeded or cascaded FELs [23][24][25][26][27], with increased coherence and shot to shot stability. More sophisticated seeding concept...

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“…For instance, one may just reduce the beam charge to produce a very short electron bunch that naturally produces a very short FEL pulse [1][2][3] . Alternatively, one may use the so-called 'slotted foil' in the center of a chicane to spoil the transverse emittance for most of the portions of the electron beam such that an ultrashort x-ray pulse is produced only from the short slices of unspoiled beam that passes cleanly through the slot [4][5][6] .…”

Section: Introductionmentioning

confidence: 99%

Generating quasi-single-cycle THz pulse from frequency-chirped electron bunch train and a tapered undulator

Wang

et al. 2016

High Pow Laser Sci Eng

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We propose a proof-of-principle experiment to test a new scheme to produce a single-cycle radiation pulse in freeelectron lasers (FELs). Here, a few α-BBO crystals will be first used to produce an equally spaced laser pulse train. Then, the laser pulse train illuminates the cathode to produce a frequency-chirped electron bunch train in a photocathode rf gun. Finally, the frequency-chirped electron bunch train passes through a tapered undulator to produce a quasi-singlecycle THz pulse. This experiment should allow comparison and confirmation of predictive models and scaling laws, and the preliminary experimental results will also be discussed.

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Generation of ultra-short, high brightness electron beams for single-spike SASE FEL operation

Cited by 92 publications

References 19 publications

Highlights on photocathodes based on thin films prepared by pulsed laser deposition

Highlights on photocathodes based on thin films prepared by pulsed laser deposition

Observation of Time-Domain Modulation of Free-Electron-Laser Pulses by Multipeaked Electron-Energy Spectrum

Generating quasi-single-cycle THz pulse from frequency-chirped electron bunch train and a tapered undulator

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