Guetg Marc
MOA03
Attoseconds at Harmonics at the European XFEL: First Results at SASE3
1
We report on the first observation of short, single-spike events generated at the SASE3 beamline of European XFEL via the “attosecond at harmonics method”. The approach was first proposed in [1]. We created bunching in the linear regime at around 0.5 keV and then, after bunching optimization by means of a magnetic chicane, we amplified the 4th harmonic bunching with a part of the undulator set to 2 keV. Due to the non-linear transformation of the bunching during the harmonic jump, radiation generated using this scheme occasionally exhibits single spike spectra (about a percent of the shots, which makes it attractive to use the method at high repetition-rate FELs). We expect those to correspond to single spikes in time-domain. We replicated the experiment numerically with the help of the GENESIS code.
Paper: MOA03
DOI: reference for this paper: 10.18429/JACoW-FEL2022-MOA03
About: Received: 17 Aug 2022 — Revised: 24 Aug 2022 — Accepted: 24 Aug 2022 — Issue date: 13 Jul 2023
MOP22
Simulation Studies for the ASPECT Project at European XFEL
52
Intense attosecond pulses generated by x-ray free-electron lasers (XFEL) are promising for attosecond science, for example, to study the quantum mechanical motion of electrons in molecules. This paper presents numerical simulations of the generation of attosecond soft and hard x-ray FEL pulses with the chirp-taper and Enhanced SASE schemes, based on the parameters of the European XFEL. To overcome the coherence time barrier, a modification of the chirp-taper scheme [1] is used in the case of soft x-rays. The results show that several hundred attosecond pulses can be obtained at photon energies of both 700 eV and 6 keV.
Paper: MOP22
DOI: reference for this paper: 10.18429/JACoW-FEL2022-MOP22
About: Received: 16 Aug 2022 — Revised: 21 Aug 2022 — Accepted: 24 Aug 2022 — Issue date: 13 Jul 2023
MOP36
Flexible Operation Modes for EuXFEL
78
A major challenge in single-linac - multiple undulator setups like EuXFEL is the generation of individual shaped photon pulses, in particular, when working in a mode where a single pulse train, or cw stream, feeds all undulator lines. This work presents the experimental verification of a flexible delivery scheme producing photon pulses for each of the three undulator lines with their electron bunches individually shaped in charge, compression and optics on a single RF pulse burst.
Paper: MOP36
DOI: reference for this paper: 10.18429/JACoW-FEL2022-MOP36
About: Received: 17 Aug 2022 — Revised: 23 Aug 2022 — Accepted: 23 Aug 2022 — Issue date: 13 Jul 2023
MOP38
Corrugated Structure System for Fresh-Slice Applications at the European XFEL
86
Fresh-slice lasing using wakefield induced time-dependent orbit oscillation is capable of producing high intensity two-color XFEL pulses and high power short pulses at femtosecond level. At the European XFEL, a corrugated structure system for fresh-slice applications for both the hard x-ray beamline SASE1 and the soft x-ray SASE3 beamline is being developed and implemented. In this contribution, we present the novel design of the corrugated structure and the application to advanced lasing schemes.
Paper: MOP38
DOI: reference for this paper: 10.18429/JACoW-FEL2022-MOP38
About: Received: 17 Aug 2022 — Revised: 25 Aug 2022 — Accepted: 25 Aug 2022 — Issue date: 13 Jul 2023
The ASPECT Project
Attosecond pulse production is an important development focus for most major FEL facilities. Chirp/taper and eSASE schemes, both of which will shorten the pulses well below the femto-second level for both hard and soft x-rays, are proposed for implementation at EuXFEL. As a high repetition rate super conducting linac that feeds three 200m long undulator lines for parallel operation, EuXFEL presents distinct challenges but also unique opportunities for the proposed schemes.
Frequency Mixing Experiments at the European XFEL
Frequency mixing was studied experimentally at SASE3, the soft X-ray undulator of the European XFEL. Two frequencies were generated in the first part of the undulator in alternating K configuration. The mixing process occurred in the second part with detuned undulator segments used to generate R56. Finally, the difference frequency was radiated and amplified in a third part of the SASE3 undulator. Experiments were performed at several electron energies (11.5 GeV, 14 GeV, and 16.5 GeV) with frequency mixing generation at photon energies between 500 eV and 1.1 keV. Pulse energies were on the mJ level, depending on the length of the radiator part. A practical application of frequency mixing at European XFEL is a possible extension of the operating range of the SASE3 undulator towards lower photon energies, by using a relatively short afterburner with longer period.
Analysis of Spectral Contents in Hard X-Ray Self-Seeded Free-Electron Laser Operation at the European XFEL
Recently, Hard x-ray self-seeding (HXRSS) operations at the European X-ray free-electron laser (EuXFEL) opened a pathway towards the application of pulses with high spectral density (in terms of ph/eV per pulse) in the fields of applied physics, chemistry and biology, where the coherent radiation spectrum is essential. The spectrum of hard x-ray self seeding pulses is generally accompanied by a pedestal around the central seeded photon energy. The pedestal contains two separate components: normal self-amplified spontaneous (SASE) and sideband emissions that can be ascribed to long-wavelength modulations of the electron beam. The pedestal limits the spectral purity and can impact some user applications. In this report, we analyze the purity of HXRSS pulses in the presence of microbunching instability. We look at the spectral contents after and before saturation, and display the contribution of the pedestal in the HXRSS spectrum.