TY  - JOUR
AU  - Urbański, Maciej
AU  - Gąsowski, Bartosz
AU  - Czuba, Krzysztof
AU  - Kola, Bartłomiej
AU  - Jatczak, Paweł
AU  - Owczarek, Tomasz
AU  - Šerlat, Andžej
AU  - Branlard, Julien
AU  - Kühn, Daniel
AU  - Ludwig, Frank
AU  - Pryschelski, Heinrich
AU  - Schulz, Katharina
TI  - An Upgrade of Radio Frequency Reference Generation and Distribution Modules for FLASH2020+
JO  - Electronics
VL  - 14
IS  - 1
SN  - 2079-9292
CY  - Basel
PB  - MDPI
M1  - PUBDB-2025-00488
SP  - 173
PY  - 2025
N1  - , agreement 5083/DESY/2020/0
AB  - Free-Electron Laser in Hamburg (FLASH), first launched in 2005, was the first free-electron laser that provided ultrashort radiation pulses in extreme ultraviolet and soft X-ray spectral range. In 2017, it was decided to improve the existing FLASH facility within the FLASH2020+ project, which led to upgrading the existing linac with variable gap tunable undulators in the FLASH1 line and refurbishing two cryomodules to achieve a beam energy increase to 1.35 GeV. It was also a perfect opportunity to completely redesign and rebuild the radio frequency (RF) phase reference generation and distribution system. This paper presents the design and parameters of new, custom-made phase reference signal generation and distribution modules, successfully installed in FLASH. These are the main oscillator, the RF distribution module, and the frequency conversion modules. The new instrumentation presents a significant improvement in terms of RF reference signal parameters, state-of-the-art phase noise performance (an improvement in the total jitter of the 1.3 GHz RF signal from 55.9 fs to 10.7 fs in the integration range from 10 Hz to 1 MHz), module compactness (size reduction from three fully occupied rack cabinets to four 19″ modules only), and serviceability. The presented Main Oscillator system design is foreseen for easy modifications, making it suitable for applications in other accelerator facilities or hardware platforms.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:001393590700001
DO  - DOI:10.3390/electronics14010173
UR  - https://bib-pubdb1.desy.de/record/622807
ER  -