03 Technology
3D Low Level RF
Paper Title Page
THPB084 A Low-Level RF Control System for a Quarter-Wave Resonator 1020
  • J.-W. Kim, D.G. Kim
    IBS, Daejeon, Republic of Korea
  • C.K. Hwang
    KAERI, Daejon, Republic of Korea
  A low-level rf control system was designed and built for an rf deflector, which is a quarter wave resonator and was designed to deflect a secondary electron beam to measure the bunch length of an ion beam. The deflector has a resonance frequency at near 88 MHz, and its required phase stability is approximately ±1° and amplitude stability less than ±1%. The control system consists of analog input and output components, and a digital system based on an FPGA for signal processing. It is a cost effective system, while meeting the stability requirements. Some basic properties of the control system were measured. Then the capability of the rf control has been tested using a mechanical vibrator made of a dielectric rod attached to an audio speaker system, which can induce regulated perturbation in the electric fields of the resonator. The control system is flexible such that its parameters can be easily configured to compensate for disturbance induced in the resonator.  
THPB085 LLRF Automation for the 9mA ILC Tests at FLASH 1023
  • J. Branlard, V. Ayvazyan, O. Hensler, H. Schlarb, Ch. Schmidt, N.J. Walker, M. Walla
    DESY, Hamburg, Germany
  • G.I. Cancelo, B. Chase
    Fermilab, Batavia, USA
  • J. Carwardine
    ANL, Argonne, USA
  • W. Cichalewski, W. Jałmużna
    TUL-DMCS, Łódź, Poland
  • S. Michizono
    KEK, Ibaraki, Japan
  Since 2009 and under the scope of the International Linear Collider (ILC) R&D, a series of studies takes place twice a year at the Free electron Laser accelerator in Hamburg, (FLASH) DESY, in order to investigate technical challenges related to the high-gradient, high-beam-current design of the ILC. Such issues as operating cavities near their quench limit with high beam loading or in klystron saturation regime are investigated, always pushing the limits of FLASH nominal operational conditions. To support these studies, a series of automation algorithms have been developed and implemented at DESY. These include automatic detection of cavity quenches, automatic adjustment of the superconducting cavity quality factor, and automatic compensation of detuning due to Lorentz forces. This paper explains the functionality of these automation tools, details about their implementation, and shows the experience acquired during the last 9mA ILC test which took place at DESY in February 2012. The benefit of these algorithms and the R&D results these automation tools have permitted will be clearly explained.  
THPB086 Precision Regulation of RF Fields with MIMO Controllers and Cavity-based Notch Filters 1026
  • Ch. Schmidt, J. Branlard, S. Pfeiffer, H. Schlarb
    DESY, Hamburg, Germany
  • W. Jałmużna
    TUL-DMCS, Łódź, Poland
  The European XFEL requires a high precision control of the electron beam, generating a specific pulsed laser light demanded by user experiments. The low level radio frequency (LLRF) control system is certainly one of the key players for the regulation of accelerating RF fields. A uTCA standard LLRF system was developed and is currently under test at DESY. Its first experimental results showed the system performance capabilities. Investigation of regulation limiting factors evidenced the need for control over fundamental cavity modes, which is done using complex controller structures and filter techniques. The improvement in measurement accuracy and detection bandwidth increased the regulation performance and contributed to integration of further control subsystems.