Available Equipment (ELI-ERIC)

Available Equipment (ELI-ERIC)

High Repetition rate laser system-based Gas High-order Harmonic Generation beamline for Gas targets - HR GHHG Gas

The High Repetition rate laser system-based Gas High-order Harmonic Generation attosecond beamline for Gas targets (HR GHHG Gas) of ELI ALPS is driven by the 100 kHz high average-power HR-1 or HR-2 laser system and produces attosecond pulse trains (APTs) for extreme ultraviolet (XUV) – infrared (IR) pump-probe measurements on gas-phase targets.

Contact person

Balázs Major


The beamline may be used for scientific experiments with its built-in diagnostics (e-TOF, photon spectrometer), or with dedicated endstations (e.g. REMi or VMI-ES).

Brief description of the available set up


The HR GHHG Gas beamline is currently providing XUV APTs on target with up to >100 pJ/shot in the 25-70 eV photon energy range at 100 kHz repetition rate [1,2]. The schematic optical layout is given in the section Main Experimental Geometries. The beamline is equipped with an electron time-of-flight (TOF) spectrometer, which serves as the primary tool for temporally characterising the XUV pulses via RABBITT [1,2], positioned in the first target area of the beamline. The beamline is designed with a second target area for an experimental end-station, provided either by ELI ALPS or by the user. For flux and spectral characterisation of the XUV, a photodiode and a flat-field spectrometer are continuously available. The beamline is in continuous upgrade and optimisation to extend the available parameter range [3].

Upon achieving the CEP stability of the driver lasers, isolated attosecond pulse production will be available (foreseen by the experimental period of this call).

Description of key areas of science


The HR GHHG Gas beamline is primarily designed to study dynamical effects on the femtosecond to attosecond timescale in gas phase targets, primarily being the subject of research in atomic-, molecular- and optical (AMO) physics. These involve control of atomic states [4], measuring photoionisation time delays [5], or imaging atomic- or molecular systems [6]. The HR GHHG Gas beamline is also a great tool for attosecond chemistry [7].

Full description of system


Representative parameters of the HR GHHG Gas beamline are given below:

  Available now (HR-1 short pulse mode, Ar gas, AI filter)*
Repetition rate 100 KHz
Energy stability 13% RMS, (±35% peak-to-peak)
Strehl ratio not available
Temporal quality not available
Pulse duration <400 as (in <12 fs attosecond pulse train)
Average power up to ~60 µW
Pulse energy (max) 600 pJ (110 pJ on target)
Pulse energy (min-max range) 6 - 600 pJ (10-110 pJ on target)
Central wavelength 25 nm (50 eV)
Spectral bandwidth 17 nm - 50 nm (25 eV - 70 eV)
Pointing stability not available
Temporal contrast (ns) not available
Temporal contrast (ps) not available
Polarisation linear (p or s) (planned upgrade for circular/elliptical polarisation)
CEP stabilisation not applicable
Near field intensity distribution Gaussian
Beam size ~130 µm (intensity FWHM, focused, based on measurement with VMI in spatial mode)

*Due to the high flexibility of the beamline, other parameters (spectral range, pulse duration, …) are available. Users are strongly suggested to contact the equipment responsible for the availability of other specifications.


Main experimental geometries


The schematic layout of the HR GHHG Gas beamline can be seen in the figure below.

Recombination of the XUV and IR beams is available separately for “Target area 1” and “Target area 2” in sections “Recombination #1” and “Recombination #2”, respectively. Due to geometrical limitations the two target areas are not available simultaneously.



Figure 2: The schematic layout of the HR GHHG Gas beamline can be seen in the figure


Available target systems


Permanent target system (“Target area 1” in “Main experimental geometries”):

  • Electron time-of-flight (TOF) spectrometer (Stefan Kaesdorf ETF-11)

  • (Potentially available for other smaller target systems provided by user)

Exchangeable target system (“Target area 2” in “Main experimental geometries”):

  • One of ELI ALPS’ end stations (e.g. VMI ES or ReMi ES have been used in combination with the HR GHHG Gas beamline)

  • User provided end station

Available metrology


The following diagnostics are available as diagnostics tools and metrology in a permanent manner in the HR GHHG Gas beamline:

  • Electron TOF spectrometer (Stefan Kaesdorf ETF-11) for temporal characterisation of the XUV APTs using the RABBITT method

  • XUV photodiode (NIST 40790C) for XUV energy measurements

  • XUV flat-field spectrometer (home built) for spectral characterisation



[1] P. Ye, L. Gulyás Oldal, T. Csizmadia, Z. Filus, T. Tímár-Grósz, P. Jójárt, I. Seres, Zs. Bengery, B. Gilicze, S. Kahaly, K. Varjú, B. Major, “High-flux 100-kHz attosecond pulse source driven by a high average power annular laser beam”, Ultrafast Science 2022, 9823783 (2022)

[2] Peng Ye, Tamás Csizmadia, Lénárd Gulyás Oldal, Harshitha Nandiga Gopalakrishna, Miklós Füle, Zoltán Filus, Balázs Nagyillés, Zsolt Divéki, Tímea Grósz, Mathieu Dumergue, Péter Jójárt, Imre Seres, Zsolt Bengery, Viktor Zuba, Zoltán Várallyay, Balázs Major, Fabio Frassetto, Michele Devetta, Giacinto Davide Lucarelli, Matteo Lucchini, Bruno Moio, Salvatore Stagira, Caterina Vozzi, Luca Poletto, Mauro Nisoli, Dimitris Charalambidis, Subhendu Kahaly, Amelle Zaïr, Katalin Varjú, “Attosecond pulse generation at ELI-ALPS 100 kHz repetition rate beamline”, Journal of Physics B: Atomic, Molecular and Optical Physics 53 (15), 154004 (2020)

[3] L. Gulyás Oldal, P. Ye, Z. Filus, T. Csizmadia, T. Grósz, M. De Marco, Zs. Bengery, I. Seres, B. Gilicze, P. Jójárt, K. Varjú, S. Kahaly, and B. Major, “All-Optical Experimental Control of High-Harmonic Photon Energy”, Phys. Rev. Applied 16, L011001 (2021)

[4] Lucchini, M., Medeghini, F., Wu, Y. et al. Controlling Floquet states on ultrashort time scales. Nat Commun 13, 7103 (2022)

[5] Ahmadi, H., Plésiat, E., Moioli, M. et al. Attosecond photoionisation time delays reveal the anisotropy of the molecular potential in the recoil frame. Nat Commun 13, 1242 (2022)

[6] Peng, P., Marceau, C. & Villeneuve, D.M. Attosecond imaging of molecules using high harmonic spectroscopy. Nat Rev Phys 1, 144–155 (2019)

[7] Mauro Nisoli, Piero Decleva, Francesca Calegari, Alicia Palacios, and Fernando Martín Chemical Reviews 117 (16), 10760-10825 (2017)