Konstantin Sukharnikov Scientific instrumentation

A hobby. An independent overview compiled from public sources by a science and space enthusiast. I am not involved in these missions or facilities; my own work is detector electronics at European XFEL. My projects →

Facility · X-ray lasers

FLASH (Free-electron LASer in Hamburg)

Superconducting free-electron laser for extreme-ultraviolet and soft X-rays, two lines: FLASH1 (externally seeded) and FLASH2 (SASE)

Status
Operating
Location
Hamburg, Germany
Operator
DESY
Next
≈ Dec 2026 – Jan 2027 first community experiments on the seeded FLASH1

Summary

The first soft X-ray free-electron laser driven by a superconducting linear accelerator, and the technology prototype for European XFEL. Pulses come in trains with an intra-train rate of 40 kHz to 1 MHz, up to 8,000 bunches per second (up to 5,000 for users). Wavelength ranges (FLASH1 figures from before the 2024–2025 shutdown): FLASH1 3.4–51 nm (24–365 eV), FLASH2 3.3–90 nm (14–376 eV); FLASH2 pulses last from under 10 to 200 fs (FLASH parameters). Under the FLASH2020+ programme, FLASH1 has been rebuilt as an externally seeded laser at high repetition rate: fully coherent pulses in a megahertz burst structure, the same challenge for detectors as at European XFEL, only at softer X-ray energies.

Now as of 9 Nov 2026

The second FLASH2020+ shutdown (June 2024 to 3 August 2025) is over. FLASH2 changed little and returned to users on 3 November 2025 (FLASH status, DESY News, 4 November 2025). The seeded FLASH1 is being commissioned; according to the status page, the first community experiments are planned for "end of 2026 / beginning of 2027". The date has slipped: in September 2025 DESY expected first seeded light for experiments in spring–summer 2026 (DESY News, 1 September 2025). DESY will publish the new FLASH1 parameters later.

Next on the operating schedule: user block 2 from 23 November to 21 December 2026, a break from 23 December 2026 to 3 January 2027, block 3 from 13 to 31 January 2027, a winter break from 1 to 21 February 2027, and block 4 from 15 March to 12 April 2027.

Key dates

  1. Jun 2024Second FLASH2020+ shutdown beginsdone
  2. 3 Aug 2025Shutdown ends, commissioning beginsdone
  3. 3 Nov 2025FLASH2 back in user operationdone
  4. ≈ Dec 2026 – Jan 2027Seeded FLASH1: first community experimentsplanned (moved from spring–summer 2026)

Timeline

  1. 4 Nov 2025FLASH2 welcomes its first users after the shutdown (an MPIK group with a reaction microscope) — DESY News
  2. 1 Sep 2025Restart after the June 2024 – August 2025 shutdown — DESY News