The FLASH Facility: Advanced Options for FLASH2 and Future Perspectives

Bart Faatz,Markus Tischer,Juliane Roensch-Schulenburg,Markus Braune,Olaf Hensler,Rolf Treusch,Mikhail Yurkov,Wilfried Wurth,Kai Tiedtke,Johann Zemella,Katja Honkavaara,Raimund Kammering,Siegfried Schreiber,Marion Kuhlmann,Elke Ploenjes,Mathias Vogt,Evgeny Schneidmiller

doi:10.3390/app7111114

Abstract

Since 2016, the two free-electron laser (FEL) lines FLASH1 and FLASH2 have been run simultaneously for users at DESY in Hamburg. With the installation of variable gap undulators in the new FLASH2 FEL line, many new possibilities have opened up in terms of photon parameters for experiments. What has been tested so far is post-saturation tapering, reverse tapering, harmonic lasing, harmonic lasing self-seeding and two-color lasing. At the moment, we are working on concepts to enhance the capabilities of the FLASH facility even further. A major part of the upgrade plans, known as FLASH2020, will involve the exchange of the fixed gap undulators in FLASH1 and the implementation of a new flexible undulator scheme aimed at providing coherent radiation for multi-color experiments over a broad wavelength range. The recent achievements in FLASH2 and the current status of plans for the further development of the facility are presented.

Highlights

FLASH began operation for experiments in the extended ultraviolet (XUV) and soft X-ray regime in summer 2005 as the world’s first short-wavelength free-electron laser (FEL) facility [1,2,3]
The advantage of variable gap undulators in terms of enhanced flexibility regarding wavelength tunability is demonstrated in Figures 2 and 3
The last undulators would no longer contribute to the FEL amplification process, resulting in lower pulse energy

Summary

Introduction

FLASH began operation for experiments in the extended ultraviolet (XUV) and soft X-ray regime in summer 2005 as the world’s first short-wavelength free-electron laser (FEL) facility [1,2,3]. Since 2016, after the installation and commissioning of a second undulator line, it has been possible for two experiments to receive a beam simultaneously [4,5]. Both FEL lines FLASH1 and FLASH2 (see Figure 1 for a layout of the facility) are currently run in self-amplified stimulated emission (SASE) mode. Using two independent photocathode lasers for FLASH1 and FLASH2, the number of bunches from a bunchtrain as well as the intra-train bunch separation going to either of the two FEL lines can be chosen freely, Appl.

Fast Wavelength Scans

New Operation Modes

Future Upgrades