Conveners
Beam Measurements and Feedback Control: Beam Measurements and Feedback Control (Tutorial)
- Roger Kalt (PSI - Paul Scherrer Institut)
Beam Measurements and Feedback Control: Beam Measurements and Feedback Control 1/2
- Wolfgang Hofle (CERN)
Beam Measurements and Feedback Control: Beam Measurements and Feedback Control 2/2
- Roger Kalt (PSI - Paul Scherrer Institut)
I will review several characteristics of low level RF (LLRF) control problems in accelerators and discuss control design methods that are well suited to these problem classes. The methods, and their key features are: i) Iterative learning control, which adapts to correct persistent disturbances in repetitive or pulsed operations; ii) Robust control with uncertainty quantification, which...
Magnetic alloy (MA) cavities are employed in the J-PARC RCS. The wideband response of the MA cavity enables the dual harmonic rf operation for the bunch shape control, which mitigates the space charge effects, while the wake voltage in a single MA cavity consists of several harmonics. Multiharmonic beam loading compensation is required for high intensity beam acceleration. We decided to employ...
Longitudinal coupled-bunch oscillations are observed with LHC-type beams in the CERN Proton Synchrotron (PS). They cause degradation of the longitudinal beam quality and beam loss. A dedicated feedback system with a wide-band Finemet cavity as a longitudinal kicker suppresses all dipolar oscillations. The existing feedback has been upgraded and extended to also damp quadrupolar modes. The...
SuperKEKB is the e-/e+ collider which targets the world highest luminosity.
In recent operation, SuperKEKB achieved a new world record $ 4.71×10^{34} cm^{-2} s^{-1} $ for luminosity with beam current $1.4A$.
In the future, beam current will be increased further to aim at the design value of $3.6A$ and much higher luminosity.
The RF system consists of 38 cavities (30 klystron stations),...
Before AI and neural nets, the excitement was about iterative learning control (ILC): the idea to train robots to perform repetitive tasks, or train a system to reject quasi-periodic disturbances. The excitement waned after the discovery of “bad learning transients” in systems which satisfy the ILC asymptotic convergence stability criteria. The transients may be of long duration, persisting...
In this contribution I will describe a method for determining cavity detuning in the CW storage ring RF systems. This method uses a vector network analyzer integrated in the LLRF system to determine the reflection coefficient versus frequency at the cavity feed port. Resulting measurement can then be fitted to extract cavity center frequency as well as other parameters of interest. The major...
For pump-probe experiments, where the FEL photon pulses interact together with an external laser, a highly temporal stability is mandatory. The longitudinal beam-based feedback system at the European XFEL stabilizes the arrival time, measured by a bunch arrival time monitor (BAM). To compensate fast arrival time fluctuations of the bunch trains, the energy in front of a bunch compression...
