Short-pulse effects in a free-electron laser

Bakker, R.J.; Jaroszynski, D. A.; Meer, A. F. G. van der; Oepts, D.; Amersfoort, P.W. van

doi:10.1109/3.299495

Cited by 34 publications

(12 citation statements)

References 17 publications

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“…In a small-gain FEL oscillator regime without limit-cycle oscillations, the group velocity of the optical pulses v g within the undulator is essentially determined by the gain-providing electron bunches, hence slower than the speed of light c 0 . Upon saturation of the radiation intensity, v g is getting closer to the vacuum value c 0 [7,21]. Consequently, the optical pulse travels ahead of the electron bunch, leading to a reduced energy extraction and decay.…”

Section: Evolution Of Fel Pulses a Experimental Resultsmentioning

confidence: 98%

“…Caused by the energy spread, the optical gain is decreasing. In a saturated, strong optical field electrons are trapped to a closed path in phase space, performing synchrotron oscillations while transversing the undulator [21]. During such an oscillation period, the particles shift back one slippage length s ¼ Nλ in relation to the optical pulse.…”

Section: Evolution Of Fel Pulses a Experimental Resultsmentioning

confidence: 99%

“…These values are about a factor of two larger than expected for a nearly transform-limited Gaussian-shaped pulse at small detuning. Previous work had argued that the FEL micropulses are expected to be transform-limited [21,34]. We ascribe this discrepancy to the evolution of the micropulse timing during the macropulse, i.e., an effective macropulse chirp, as detailed in the following section.…”

Section: Fel Pulse Profilementioning

confidence: 89%

“…The 4D simulation used in this paper has been studied extensively and compared to many FEL amplifier and oscillator experiments [19]. Furthermore, pronounced nonlinear processes like subpulse formation and limit-cycle oscillations (LCOs) of the power have been predicted for short electron bunches within an oscillator-type FEL [20,21]. Our experimental cross-correlation measurements provide both delay-time as well as real-time resolution and thus give insight into these processes in yet unprecedented contrast and detail, as opposed to previous one-dimensional studies [5,7].…”

Section: Introductionmentioning

confidence: 99%

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Femtosecond single-shot timing and direct observation of subpulse formation in an infrared free-electron laser

Kiessling

Colson

Gewinner

et al. 2018

Phys. Rev. Accel. Beams

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We experimentally demonstrate a single-shot arrival time monitor for short picosecond infrared freeelectron laser (IR FEL) pulses based on balanced optical cross-correlation with a synchronized fs table-top laser. Employing this timing tool at the Fritz Haber Institute IR FEL, we observe a shot-to-shot timing jitter of only 100 fs and minute-scale timing drifts of a few picoseconds, the latter being strictly correlated with the electron beam energy of the accelerator. We acquire sum-frequency cross-correlation data with micropulse resolution, providing full access to the IR FEL pulse shape evolution within the macropulse. These measurements provide unprecedented insights into the occurrence of limit-cycle oscillations of the FEL intensity as a consequence of subpulse formation. Our experimental results are complemented by fourdimensional simulations of the nonlinear pulse dynamics in a low-gain FEL oscillator based on MaxwellLorentz theory.

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Section: Evolution Of Fel Pulses a Experimental Resultsmentioning

confidence: 98%

Section: Evolution Of Fel Pulses a Experimental Resultsmentioning

confidence: 99%

Section: Fel Pulse Profilementioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Femtosecond single-shot timing and direct observation of subpulse formation in an infrared free-electron laser

Kiessling

Colson

Gewinner

et al. 2018

Phys. Rev. Accel. Beams

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“…All these features are in good agreement with the expected behavior of an oscillator FEL as it was observed previously at the FELIX IR FEL. [11][12][13][14] An oscillator FEL can operate in different regimes depending on the cavity detuning ∆L. At ∆L = 0 the gain drops to zero and no lasing is achieved.…”

Section: Temporal Characterization Of the Fel Micro-pulses By Autocormentioning

confidence: 99%

The new IR and THz FEL facility at the Fritz Haber Institute in Berlin

et al. 2015

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A mid-infrared oscillator FEL has been commissioned at the Fritz Haber Institute. The accelerator consists of a thermionic gridded gun, a subharmonic buncher, and two S-band standing-wave copper structures. It provides a final electron energy adjustable from 15 to 50 MeV, low longitudinal (< 50 keV ps) and transverse emittance (< 20 πmm mrad), at more than 200 pC bunch charge with a micro-pulse repetition rate of 1 GHz and a macro-pulse length of up to 15 µs. Pulsed radiation with up to 100 mJ macro-pulse energy at about 0.5% FWHM bandwidth is routinely produced in the wavelength range from 4 to 48 µm. A characterization of the FEL performance in terms of pulse energy, bandwidth, and micro-pulse shape of the IR radiation is given. In addition, selected user results are presented. These include, for instance, spectroscopy of bio-molecules (peptides and small proteins) either conformer selected by ion mobility spectrometry or embedded in superfluid helium nano-droplets at 0.4 K, as well as vibrational spectroscopy of mass-selected metal-oxide clusters and protonated water clusters in the gas phase. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

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Introduction

Freund,

Antonsen,

2023

Principles of Free Electron Lasers

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Short-pulse effects in a free-electron laser

Cited by 34 publications

References 17 publications

Femtosecond single-shot timing and direct observation of subpulse formation in an infrared free-electron laser

Femtosecond single-shot timing and direct observation of subpulse formation in an infrared free-electron laser

The new IR and THz FEL facility at the Fritz Haber Institute in Berlin

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