Design of the Stripline and Kickers for Alba (original) (raw)
Related papers
2018
The extraction system for the CLIC Damping Rings has very tight specifications. Therefore a full characterisation of the behaviour of the stripline kicker under conditions as close as possible to the expected working conditions will be very valuable. To that end the CLIC stripline has been installed in the ALBA Synchrotron Light Source and has been characterised with beam. Prior to its installation, the effect of the stripline kicker on the machine impedance has been assessed. The installation has required the design of an absorber to screen the stripline from synchrotron radiation and additional BPMs have been installed for a better kick angle determination. The commissioning of the stripline with beam has been performed following closely beam parameters, pressure and temperature. The studies with beam include the determination of the longitudinal and transverse impedance of the kicker*, the field homogeneity when excited with a dc field and the field ripple when pulsed. This contr...
Measurements and Laboratory Tests on a Prototype Stripline Kicker for the Clic Damping Rings
The Pre-Damping Rings (PDRs) and Damping Rings (DRs) of CLIC are required to reduce the beam emittances to the small values required for the main linacs. The injection and extraction, from the PDRs and DRs, are performed by kicker systems. To achieve both low beam coupling impedance and reasonable broadband impedance matching to the electrical circuit, striplines have been chosen for the kicker elements. Prototype striplines have been built: tests and measurements of these striplines have started. The goal of these tests is to characterize, without beam, the electro-magnetic response of the striplines. The tests have been carried out at CERN. To study the signal transmission through the striplines, the measured S-parameters have been com-pared with simulations. In addition, measurements of longitudinal beam coupling impedance, using the coaxial wire method, are reported and compared with simulations.
Design and Implementation of Stripline Feedback Kickers in the MAX IV 3 GeV Ring
2017
The commissioning of a bunch-by-bunch feedback system for the MAX IV 3 GeV storage ring was started in early 2016. At date, the actuators are two stripline kickers oriented in the horizontal and in the vertical plane, respectively. Apart from providing feedback in the transverse plane, the horizontal stripline is simultaneously operating as a longitudinal kicker. This is done by upconverting the longitudinal 0 - 50 MHz baseband signal to the 150 MHz - 250 MHz range where the longitudinal shunt impedance of the stripline is higher. This signal is then fed to the stripline electrodes in common-mode. The design of the stripline kickers and the layout of the bunch-by bunch feedback system in the 3 GeV ring are presented in this report. Results from instability studies in this ring are also discussed.
A Retrofit Technique for Kicker Beam-Coupling Impedance Reduction, EPAC04, Lucerne
2004
The reduction of the impedance of operational ferrite kicker structures may be desirable in order to avoid rebuilding such a device. Often resistively coated ceramic plates or tubes are installed for this purpose but at the expense of available aperture. Ceramic U-shaped profiles with a resistive coating fitting between the ellipse of the beam and the rectangular kicker aperture have been used to significantly reduce the impedance of the magnet, while having a limited effect on the available physical aperture. Details of this method, constraints, measurements and simulation results as well as practical aspects are presented and discussed.
2015
A first stripline kicker prototype for beam extraction from the CLIC Damping Rings (DRs) has been designed at IFIC and CIEMAT, with excellent field homogeneity, good power transmission and low beam coupling impedance. The prototype has been built by the company Trinos Vacuum Projects, and laboratory tests and measurements have been carried out at CERN to characterize, without beam, the electromagnetic response of the striplines. In this paper, we present the measurements of the transverse beam coupling impedance, using the coaxial wire method, and a comparison with simulations. Furthermore, results of DC breakdown tests, using High Voltage (HV) power supplies, are also reported. TRANSVERSE BEAM COUPLING IMPEDANCE MEASUREMENTS Measurements in the laboratory, without beam, are important to characterize the electromagnetic response of the striplines, and compare the results of the measurements with the electromagnetic simulations. The measurements carried out in this first prototype ha...
2017
The ALS upgrade to a diffraction-limited light source (ALS-U Project) relies on a swap-out injection scheme, where the circulating current is maintained constant by injecting on-axis fresh bunch trains replacing old trains, which are simultaneously extracted. The realization of a stripline kicker to perform such an operation presents several challenges in terms of optimal matching to the pulser, contributions to the beam coupling impedance, and dissipation of the power deposited by the stored beam. To test our design choices for the ALS-U kicker, we have built and installed on the ALS a test kicker with characteristics similar to the design for the ALS-U, as the more challenging aspects of the project are concerned. In particular, while the small distance between stripline electrodes reduces the required pulser voltage, the extreme proximity of the circulating beam requires a careful evaluation of the interaction between beam and kicker. In this paper we present the measurement techniques used to improve the alignment of the stripline electrodes during assembly and monitor their status after installation on the ALS.
A retrofit technique for kicker beam-coupling impedance reduction
EPAC, 2004
The reduction of the impedance of operational ferrite kicker structures may be desirable in order to avoid rebuilding such a device. Often resistively coated ceramic plates or tubes are installed for this purpose but at the expense of available aperture. Ceramic U-shaped profiles with a resistive coating fitting between the ellipse of the beam and the rectangular kicker aperture have been used to significantly reduce the impedance of the magnet, while having a limited effect on the available physical aperture. Details of this method, constraints, measurements and simulation results as well as practical aspects are presented and discussed.
Design of longitudinal feedback system kicker for the PLS storage ring
Proceedings of the 1999 Particle Accelerator Conference (Cat. No.99CH36366)
The higher order modes (HOMs) of RF cavities at the Pohang Light Source (PLS) storage ring cause longitudinal coupled bunch mode instabilities (CBMIs). To cure these instabilities, a longitudinal feedback system (LFS) is introduced. As a key component of the LFS, there is a single-ridged waveguide-overloaded cavity as a longitudinal bunch-by-bunch LFS kicker for the PLS storage ring. To damp any coupled bunch modes, the bandwidth of this kicker should be wider than 250 MHz. Also, the higher shunt impedance of the kicker is selected to use lower power amplifier. One aluminum kicker is fabricated and the bandwidth, HOMs, and shunt impedance of the kicker are measured with a network analyzer. This kicker has several different features from LFS kicker for DAऄNE. First of all, there are 4 input/output ports to obtain a wider bandwidth. Secondly, there is a nose cone to obtain higher shunt impedance. Finally, the symmetric frequency response of the shunt impedance around central frequency is provided. According to the simulation result done by HFSS code, high shunt impedance of 620 ae (transit time factor considered value) and the wide bandwidth of 255 MHz are obtained. These are compared with the measured result.
Development of the RF Kicker for the Longitudinal Feedback System at SRRC
SRRC is currently developing a RF kicker for the lon- gitudinal feedback system. The kicker is a pill-box cavity with nine pieces of striplines. The resonant frequency is tuned to the designing value 1125 MHz by adjusting the length of the striplines. Excited by a single stripline, cold test results indicate that the full 3 dB bandwidth exceeds 250 MHz and the shunt impedance deduced from bead-pull measurement is about 80