Speaker
Dr
Wojciech Cichalewski
(Technical University of Lodz)
Description
Modern digital low level radio frequency (LLRF) control systems used
to stabilize the accelerating field in facilities such as Free
Electron Laser in Hamburg (FLASH) or European X-Ray Free Electron
Laser (E-XFEL) are based on the Field Programmable Gate Array (FPGA) technology. Presently these accelerator facilities are operated
with pulsed RF. In future, these facilities should be operated with
continuous wave (CW) which requires significant modifications on the
real-time feedbacks realized within the FPGA. For example, higher
loaded quality factor of the cavities when operated in a CW mode
requires sophisticated resonance control methods. However,
iterative learning techniques widely used for machines operated in
pulsed mode are not applicable for CW. In addition, the mechanical
characteristic of the cavities have now a much more important impact
on the choice of the feedback scheme. To overcome the limitations of
classical PI-controllers novel real-time adaptive feed forward
algorithm are implemented in the FPGA. Also, the high power RF
amplifier which is an inductive output tube (IOT) for continuous
wave operation instead of a klystron for the pulsed mode has major
impact on the design and implementation of the firmware for
regulation. In this paper, we report on our successful approach to
control multi-cavities with ultra-high precision (dA/A<1e-4,
dphi<2e-2 deg) using a single IOT source and individual resonance
control through piezo actuators. Performance measurements of the
proposed solution were conducted at Cryo Module Test Bench (CMTB)
facility.
Author
Mr
Radoslaw Rybaniec
(Warsaw University of Technology)
Co-authors
Dr
Christian Schmidt
(DESY)
Dr
Holger Schlarb
(DESY)
Dr
Jacek Sekutowicz
(DESY)
Dr
Julien Branlard
(DESY)
Dr
Konrad Przygoda
(DESY)
Mr
Lukasz Butkowski
(DESY)
Sven Pfeiffer
(DESY)
Dr
Valeri Ayvazyan
(DESY)
Dr
Wojciech Cichalewski
(Technical University of Lodz)
