TY  - JOUR
AU  - Ludwig, Frank
AU  - Branlard, Julien
AU  - Hoffmann, Matthias
AU  - Mavric, Uros
AU  - Pryschelski, Heinrich
AU  - Springer, Louise
AU  - Schlarb, Holger
TI  - RF controls based on carrier suppression detection with attosecond resolution
JO  - Physical review accelerators and beams
VL  - 28
IS  - 7
SN  - 2469-9888
CY  - College Park, MD
PB  - American Physical Society
M1  - PUBDB-2024-06331
SP  - 072803
PY  - 2025
AB  - In this paper, an RF control system with attosecond resolution based on carrier suppression interferometer operating a superconductive cavity at the Cryo Module Test Bench (CMTB) is presented. This novel application of the carrier suppression detector extends conventional heterodyne methods and improves the residual jitter of the regulated RF field in the cavity by more than one order of magnitude. The cavity was operated at 1.3 GHz frequency at a gradient of 8 MV/m and with a loaded quality factor of 10<sup>7</sup>. An out-of-loop phase noise detection floor of \mathscrL=−180 dBc/Hz and outstanding time resolution of 189 as within an offset frequency range from 10 Hz to 1 MHz have been achieved. The phase noise budget of sub-components such as in-loop and out-of-loop detectors, high-power drive, microphonics and the reference source are reported. The facility RF reference and its phase noise in the offset frequency range from 1 kHz to 100 kHz is identified as the key noise contributor. Furthermore, above the closed-loop system bandwidth, due to filtering of the narrow band cavity the phase jitter contribution is further reduced to approximately 116 as only. The presented research using conventional receiver techniques with carrier suppression detectors in continuous-wave (CW) operation is an important milestone towards attosecond resolution pump-probe experiments at Free Electron Lasers.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1103/jhc3-dtzw
UR  - https://bib-pubdb1.desy.de/record/616039
ER  -