| Paper | Title | Other Keywords | Page |
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| MOPE005 | Countermeasure to Suppress the Filling Pattern Dependence of the BPM Electronics of SPring-8 Storage Ring | storage-ring, electron, pick-up, controls | 960 |
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The signal processing electronics of the SPring-8 Storage Ring BPM were replaced during the summer shutdown of 2006, and put into operation. However, a large filling pattern dependence was observed. The cause was attributed to the nonlinear response of the diodes to large pulse signals. The diode were attached in front of the RF switches for protection from the electrostatic discharge damages on the switch IC. We took a countermeasure for the filling pattern dependence by reducing the pulse height with a band pass filter (BPF) in front of each channel. The BPF were attached and put into the operation from November 2008. The effect of the BPF was evaluated using the beam with changing the filling patterns and repeating the position measurements. The differences of the measured position data across the filling pattern change were found to be within 10μmeters, which was the same amount of the orbit drift during the filling pattern change. |
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| TUPE025 | Development Status of RF System of Injector Section for XFEL/SPring-8 | cavity, electron, controls, bunching | 2194 |
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XFEL/SPring-8 is under construction, which is aiming at generating coherent, high brilliance, ultra-short femto-second X-ray pulse at wavelength of 1Å or shorter. The injector consists of a 500kV thermionic gun (CeB6), a beam deflecting system, multi-stage RF structures and ten magnetic lenses. The multi-stage RF structures (238MHz, 476MHz, 1428MHz) are used for bunching and accelerating the beam gradually to maintain the initial beam emittance. In addition, in order to realize linearizing the energy chirp of the beam bunch at three magnetic bunch compression systems after the injector system, we prepared extra RF structures of 1428MHz and 5712MHz. It is important to stabilize the gap voltage of those RF structures because the intensity of X-ray pulse is more sensitive for a slight variation of the RF system in the injector. We developed some stable amplifiers for those RF structures, and confirmed the amplitude and phase stability of an RF signal outputted from the amplifiers. The measurement results achieved nearly the requirement of design parameters. In this paper, we describe the development status and the achieved performances of RF equipment of the injector section. |
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| WEPEC013 | Phase Locking of Superconducting Quarter Wave Resonator by Piezoelectric Actuator | controls, cavity, linac, niobium | 2920 |
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The existing phase locking scheme of the quarter wave resonators(QWR) in the first operational module of the superconducting heavy ion linear accelerator of Inter University Accelerator Centre consists of a fast (electronic) and a slow time scale control. Helium gas operated slow tuner turns out to be a complicated, somewhat unreliable and expensive for long term operation of the linac. In an alternate scheme to handle the slow time part of the phase control, the tuner plate is deflected by using a combination of a stepper motor for course adjustments and a piezoelectric crystal for fine adjustment of the frequency. The piezoelectric actuator is used in closed loop along with dynamic I-Q based electronic tuner to phase lock the superconducting cavities. During a recent cold test of a QWR, the frequency range of the resonator by the piezoelectric tuner was measured to be 1 kHz. In this test, the fundamental frequency of the QWR was first brought to 97.000 MHz by the mechanical course tuner. The resonator was then locked at a field of 3.8 MV/m at 6 W of helium power and 40 W of forward power from the RF amplifier using the resonator controller along with the piezoelectric tuner. |
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| WEPD090 | Design Concepts for RF-DC Conversion in Particle Accelerator Systems | coupling, cavity, simulation, electron | 3308 |
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In many particle accelerators considerable amounts of RF power reaching the megawatt level are converted into heat in dummy loads. After an overview of RF power in the range 200 MHz to 1 GHz dissipated at CERN we discuss several developments that had come up in the past using vacuum tube technology for RF-DC conversion. Amongst those the developments the cyclotron wave converter CWC appears most suitable. With the availability of powerful Schottky diodes the solid state converter aspect has to be addressed as well. One of the biggest problems of Schottky diode based structures is the junction capacity. GaAs and GaN Schottky diodes show a significant reduction of this junction capacity as compared to silicon. Small rectenna type converter units which had been already developed for microwave powered helicopters can be used in waveguides or with coaxial power dividers. |
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| THPEB054 | The Development of High Power Solid-state Amplifier in NSRRC | impedance, controls, synchrotron, coupling | 3993 |
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The RF power source using solid-state amplifier for accelerator application has become popular in recent years. The amplifiers array using power divider and power combiner could obtain equivalent power level as those using klystron or IOT. Such solid-state RF power source also has the advantage of easy maintenance, low cost, low DC power voltage and high flexibility. The development of solid-state power amplifier module at 499.65 MHz using the latest RF power chip has been built to have the power level of 900 Watts with above 60% efficiency of single power module. The more power that one module can provide, the less number of modules would be required under the same total output power of amplifiers array. Thus, the construction of a transmitter by solid-state technique for RF system would be less complex for easy maintenance. |