Instrument design

The High Energy Density science (HED) instrument will be a unique platform for experiments combining hard X-ray FEL radiation and the capability to place matter under extreme conditions of pressure, temperature, or electric field using the FEL, high-energy optical lasers, diamond anvil cells, or pulsed magnets.

X-ray transport

HED is located at the hard X-ray SASE2 undulator at the south side branch. Energies between 3 and 25 keV are accessible. Focusing schemes are based on compound refractive lenses (CRL). With CRL lenses at four different positions, spot sizes of 1 mm – sub µm are enabled at the sample position. A split and delay line (SDL) allows X-ray pump–X-ray probe experiments in the energy range 5–20 keV with maximum delays of 23 and 2 ps, respectively. Three different energy bandwidths are available at HED: 10-3 for 3–25 keV (no monochromator), 10-4 for 5–25 keV (Si111), and 10-6 for dedicated energies (high-resolution monochromator). Repetition rates for experiments are pulse-on-demand, 10 Hz and up to 4.5 MHz for special experiments.

The SDL is a contribution from the BMBF.

Excitation sources

Four optical laser systems shall be installed at the HED instrument:

  • 100 TW short-pulse high-intensity optical laser (HI-OL). λ=0.8 µm
  • 100 J/ns long-pulse high-energy optical laser (HE-OL). λ=0.5 µm (second harmonic)
  • Pump–probe laser (PP-OL). 3 mJ/~15 fs/λ=0.8 µm or 100 mJ/0.8 ps/λ=1 µm, chirped mode (for ns pulse duration possible)

Pulsed magnet: 50–60 T over microsecond duration
Diamond anvil cells: dynamic and double stage
FEL beam

The HI-OL, HE-OL, and pulsed magnet are contributions from the HIBEF user consortium.

The heavy concrete HED-EXP enclosure in October 2014.

Experiment room arrangement

The main experiment room is 11.4 m long and 9 m wide internally. Its inner clear height is 4 m. Due to secondary radiation generated by a high-intensity optical laser, this area is enclosed by 50–100 cm thick heavy concrete walls. The HED-EXP enclosure and the heavy-load door were completed in July 2014.

Sample delivery

The main target stage allows for fast sample scan movements. Solid samples will be exchangeable in vacuum using a robotic arm system. Fast recovery sample environments using liquid crystal technlogy and liquid jets are the subject of collaborations and ongoing research.

CAD illustration of the HED main interaction chamber.

Detectors

Inside the main interaction vacuum chamber, small area detectors are foreseen that have chip sizes of >25 mm x >50 mm and pixel sizes ranging from 50 µm to 100 µm. These detectors can be positions according to the experimental setup. Large area detectors for X-ray diffraction experiments are planned as part of external user consortium contributions.

Technical Design Report

  • Technical Design Report: Scientific Instrument High Energy Density Physics (HED)

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