| Paper | Title | Page |
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| MOPC119 | Low-Output-Impedance RF System for the ISIS Second Harmonic Cavity | 343 |
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| Low-output-impedance RF system for the second harmonic cavity in the ISIS synchrotron has been developed by the collaboration between Argonne National Laboratory, US, KEK, Japan and Rutherford Appleton Laboratory, UK. Low output impedance is realized by the feedback from plate output to grid input of the final triode amplifier, resulting in less than 30 Ω over the frequency range of interest. Precise control of the second harmonic voltage can then be realized without considering beam loading effects. Beam test scenario in the ISIS synchrotron is discussed. | ||
| MOPD016 | ALS Storage Ring RF System Upgrade | 478 |
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| ALS is one of the first third generation synchrotron light sources which has been operating since 1992 at Berkeley Lab. Presently, the ALS Storage Ring System is comprised of a single 330kW klystron feeding two normal-conducting single-cell RF cavities via a WR1800 circulator and magic-tee transmission system. The klystron has operated well beyond its expected lifetime and even though replacement klystrons are available from a different manufacturer, we have opted to build the replacement amplifier with a system of four Inductive Output Tubes, (IOT). The new amplifier system will use Cavity Combiners (CaCo) to combine IOT outputs and a magic-tee to combine IOT pairs to feed the existing transmission line connected to the cavities. The existing HVPS will be upgraded to interface with the four IOT amplifiers and its crowbar will be replaced with a series solid-state switch. The system is being designed to operate with the industry standard external cavity IOTs (80kW) and integral cavity IOTs (90-100kW). In this paper we will present the details of the upgrade of each of the sub-systems in the ALS Storage Ring RF System. | ||
| MOPD022 | New 1MW 704MHz RF Test Stand at CEA-Saclay | 490 |
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| In the frame of the european CARE/HIPPI programme, superconducting accelerating cavities for pulsed proton injectors are developed. Qualification of these 704 MHz RF structures fully equipped (housed in a helium tank, with tuning system and power coupler), requires to perform high power tests in the existing horizontal cryostat CryHoLab. During the last years, CEA-Saclay built and ordered the necessary RF equipments to make such a platform for high power RF tests in a cryogenic environment available to the partners in HIPPI and later on to any other interested European teams. The main components of the RF test stand (95 kV-275kVA DC High Voltage Power Supply, 50Hz modulator and 1MW 704.4MHz RF klystron amplifier) are now installed and tested. In this paper, we present the different components with a focus on the new design of the hard tube modulator to match the new specifications and the compatibility with the floating HVPS, the results of the HV and RF measurements performed and we give a brief description of the PXI-based controller for the interlocks and klystron auxiliary controls. | ||
| MOPD023 | Parametric Study of a Novel Coaxial Bunched Beam Space-charge Limit | 493 |
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Recently, a non-trivial space-charge limit for off-axis bunched electron beams in a coaxial conducting structure was derived theoretically*. The space-charge limit describes the minimum strength of an external solenoidal focusing field which is needed to stabilize the beam’s center-of-mass motion in the presence of induced surface charges on the coaxial structure. In this paper, we perform a parametric study of the space-charge limit to numerically determine its dependency on the conducting structure geometry, i.e., the ratio of the inner and outer conductor radii, as well as its’ dependency on the transverse and longitudinal bunch distributions. As an application, we show how this parametric study can be important for the design of high-power microwave sources, such as the UC-Davis/SLAC 2.8 GHz coaxial ubitron oscillator**.
*M. Hess, accepted for publication in IEEE Trans. Plasma Sci. (2008). |
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| MOPD024 | RF Power System for the IFMIF-EVEDA Prototype Accelerator | 496 |
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| The IFMIF-EVEDA accelerator will be a 9 MeV, 125 mA cw deuteron accelerator prototype for verifying the validity of the accelerator design for IFMIF. The RFQ, matching section and DTL resonant cavities must be fed with continuous RF power at 175 MHz frequency with an accuracy of 1% in amplitude and ± 1° in phase. Currently two possible solutions for the DTL design are considered. The first option consists of normal conducting (NC) Alvarez type cavities and the second option consists of superconducting (SC) Half Wave Resonator cavities. Both options impose different demands on the RF system which are analyzed in this paper. The RF power system will be made of several amplification stages and will be based on vacuum tube amplifiers. The main characteristics of RF system including those of the high voltage power sources required to feed the anodes of the high power tubes will be presented in this paper. | ||
| MOPD025 | Status of the 805-MHz Pulsed Klystrons for the Spallation Neutron Source | 499 |
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| Communications and Power Industries, Inc (CPI) produced 81 klystrons for the Spallation Neutron Source at Oak Ridge National Laboratory. The klystrons are rated for 550 kW peak at 805 MHz. Seventy units have accumulated 1.2M hours of filament operation and 820K hours of high voltage operation through January 2008. A higher power 700 kW version has been developed and is now in production with 12 of the 38 units on order delivered through January 2008. Performance specifications, computer model predictions, operating results, production statistics, and operational status will be presented. | ||
| MOPD028 | Radio Frequency Power Sources for the Muon Ionisation Cooling Experiment | 508 |
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| For any future Neutrino Factory the accelerator aperture will be a major cost driver. Potentially the aperture can be reduced and significant capital savings made if ionisation cooling is utilised on the muon beam. In order to demonstrate the effectiveness of ionisation cooling a demonstrator needs to be built and operated. MICE, the Muon Ionisation Cooling Experiment is that demonstrator. The RF requirements of MICE will be met using high power vacuum tube based RF circuits donated by LBNL and CERN. This paper will discuss these circuits, their refurbishment, the construction of HT power supplies and ancillary equipment and high power testing. | ||
| MOPD029 | Commissioning of the 2,2 kW, 476 MHz Solid State RF Power Source for the LNLS Booster Synchrotron | 511 |
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| A 2.2 kW, 476 MHz unconditionally stable solid state RF amplifier for CW operation has been built, tested, and is being used since july 2007 at LNLS. The amplifier, designed and developed in collaboration with Synchrotron SOLEIL, is made of 9 modules, each one containing one push-pull 290 W MOSFET equipped with an internal circulator and RF load. Low cost, reliability, linearity and high efficiency are the main features we aimed for in this device, which was developed for the LNLS Booster Injector. In this paper, we present technical characteristics as well as test results of the system. | ||
| MOPD033 | The ALBA RF Amplifier System Based on Inductive Output Tubes (IOT) | 523 |
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| The ALBA accelerator RF systems include a complete new transmitter developed in collaboration between Thomson Broadcast & Multimedia (TBM), Thales Electron Devices (TED) and CELLS. A new IOT version, based on the previous TH793 has been developed by TED: the TH793-1, dedicated to scientific applications. It has demonstrated cw operation up to 90 kW at 500 MHz. In addition, a TH18973 LS cavity has also been developed, featuring a 6”1/8 coaxial RF output, an optimized cooling system and centred operation at 500 MHz, 7 MHz bandwidth and ± 5 MHz tuning range. TBM developed a new amplifier system to achieve high reliability and performance. Each IOT is powered by an individual power supply based on the Pulse Step Modulator technology. The amplifier control system was designed on a PLC controller with the possibility to interface with the Tango control system. The first amplifier was delivered to ALBA in summer 2007 and is already in use for the conditioning and testing of the first RF cavity. The remaining 13 amplifiers will be delivered in the second half of 2008. The paper gives an overview on the design and operation performance during commissioning and cavity testing. | ||
| MOPD034 | Status of the High Power, Solid-State RF Amplifier Development at Laboratori Nazionali di Legnaro | 526 |
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| The development of high power, unconditionally stable solid-state amplifiers for superconducting low-beta cavities, performed at Laboratori Nazionali di Legnaro in the framework of the EURISOL Design Study, has led to the construction and testing of two, newly designed 10 kW units that can be used both individually or coupled together to obtain a 20 kW source. Characteristic of this family of amplifiers, based on parallel assemblies of 300W modules equipped with mosfets and individual circulators, is their possibility of operating in any matching conditions and also, at a reduced power, in case of failure of one mosfet. Characteristics of the amplifiers and of the high power combiner will be described, and their performance and test results will be reported. | ||
| MOPD035 | 20 MW Pulse Amplifier Klystron with Multiple Frequency Two-Gap Bunching Resonators for Linear Electron Accelerators | 529 |
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| A klystron design with a two-gap bunching resonator which provides interaction with electron beam by fields of multiple frequencies of two-gap resonator fundamental oscillations for increasing the klystron efficiency is being considered. At that the two-gap resonator is tuned to antiphased oscillation at operating frequency and to in-phase oscillation at the second harmonic. Such choice of frequency oscillation types allows to make the resonator compact and provide optimal conditions for electron beam interaction with microwave fields of the two-gap resonator both in antiphased and in-phase oscillation types. The relations for choosing two-gap resonator interaction area size providing a stable klystron operation without self-excitation are given. The compactness of the realized two-gap resonator with multiple frequencies allowed to locate it into klystron drift tube between the main resonators without increasing the klystron overall dimensions. The results of experimental research of klystron with such a two-gap resonator showed a possibility to increase its efficiency significantly. | ||
| MOPD042 | Design and Testing of the Horizontal Version of the Multi Beam Klystron for European XFEL Project | 544 |
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| Toshiba Electron Tubes & Devices (TETD) has been developing 10-MW L-band Multi-Beam Klystrons (MBKs) for the European XFEL project and possibly for future linear colliders. In order to allow horizontal installation in the XFEL tunnel, the horizontal version of MBK, MBK E3736H, has been designed, fabricated and tested by TETD. The MBK has six low-perveance beams operated at low voltage of less than 120 kV (for 10MW) and six ring-shaped cavities. In the successful acceptance testing at TETD in August 2007, the MBK achieved an output power of 10.3 MW at the beam voltage of 117 kV and at the RF pulse width of 1.5ms with efficiency of 67%. This test demonstrated that MBK E3736H fulfills all the requirements necessary as the RF power source of the XFEL linac. | ||
| MOPP092 | Efficient Fan-out RF Vector Control Algorithm | 766 |
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| A new RF vector control algorithm for fan-out power distribution using reactive transmission line circuit parameters for maximum power efficiency is presented. This control with fan-out power distribution system is considered valuable for large scale SRF accelerator systems to reduce construction costs and save on operating costs. Other fixed power splitting systems with individual cavity voltage control at each cavity input may not deliver the power efficiency since excessive power needs to be maintained at each cavity input. In a fan-out RF power distribution system, feeding multiple accelerating cavities with a single RF power generator can be accomplished by adjusting phase delays between the load cavities and reactive loads at the cavity inputs for independent control of cavity RF voltage vectors. In this approach, the RF control parameters for a set of specified cavity RF voltage vectors is determined for a whole fan-out system. The reactive loads and phase shifts can be realized using high power RF phase shifters. | ||
| MOPP116 | Commissioning of the Cornell ERL Injector RF Systems | 832 |
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| Two high power 1300 MHz RF systems have been developed for the Cornell University ERL Injector. The first system, based on a 16 kWCW IOT transmitter, is to provide RF power to a buncher cavity. The second system employs five 120 kWCW klystrons to feed 2-cell superconducting cavities of the injector cryomodule. The sixth, spare klystron is used to power a deflecting cavity in a pulsed mode for beam diagnostics. A digital LLRF control stem was designed and implemented for precise regulation of the cavities’ field amplitudes and phases. All components of these systems have been recently installed and commissioned. The results from the first turn-on of the systems are presented. |