| Paper | Title | Page |
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| THPIK001 | Copper Accelerating Structure Fabrication With Controled Cu-Ag Joining Conditions | 4104 |
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| The paper is devoted to the development of technological processes of copper accelerating structures fabrication from oxygen-free copper. The experimental set-up for vacuum brazing of long accelerating structures with optimal Cu-Ag joining conditions is described. The experimental results of precise machining and subsequent vacuum brazing of Ag-Cu eutectic are presented | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK001 | |
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| THPIK002 | Development of a Range of High Peak Power Solid-State Amplifiers for Use in the Heavy Ion Linac at JINR, Dubna | 4108 |
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| A range of LDMOS based amplifiers rated for up to 340kW peak power and operating at 100.625MHz were developed for use as RF sources for driving cavities in the heavy ion LINAC (HILac) at JINR, Dubna. The final solution had to be compact and competitive while addressing technical challenges such as phase and amplitude stability, long term reliability, reflected power handling and serviceability. Design considerations and performance results are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK002 | |
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| THPIK003 | Novel RF Structure for Energy Matching into an RFQ | 4111 |
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Funding: National Research Council of Canada The ISAC RFQ at TRIUMF is designed to accelerate ions with A/q<=30 and requires an ion injection energy of 2.04 keV/u (β=0.002) for successful matching. This means that the ions (typically radioactive ions produced via the ISOL method) have to be extracted from a source at a terminal voltage in excess of 60 kV. Presently the ISAC target modules cannot hold more than 54 kV (and some lower than this) so that some of the higher masses cannot be successfully accelerated. A small 3-gap RF structure at 11.8 MHz has been designed to provide an energy matching to the RFQ. The structure operates in pi-mode and provides a maximum effective accelerating voltage of 16 kV to the low energy ions. Beam dynamics considerations, RF and mechanical design will be described. First results of RF tests of the structure will be given. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK003 | |
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| THPIK005 | RF Conditionning of the Spiral 2 CW RFQ | 4114 |
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| The SPIRAL2 RFQ is designed to accelerate light and heavy ions with A/Q from 1 to 3 at 0.73 MeV/A. The nominal beam intensities are up to 5 mA CW for both proton and deuteron beams and up to 1 mA CW for heavier ions. The four-vane cavity is made with 5 1-meter long sections mechanically assembled, it works at 88 MHz and is powered up to 180 kW CW to achieve the nominal vane voltage of 113.7 kV for A/Q = 3 ions. This paper describes the RF conditioning of the RFQ at GANIL with the setting of its RF systems and cooling system used to tune the cavity resonance frequency. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK005 | |
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| THPIK007 | Production of Low Cost, High Field Quality Halbach Magnets | 4118 |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A shimming method has been developed at BNL that can improve the integrated field linearity of Halbach magnets to roughly 1 unit (1 part in 104) at r=10mm. Two sets of magnets have been produced: six quadrupoles of strength 23.62T/m and six combined-function (asymmetrical) Halbach magnets of 19.12T/m with a central field of 0.377T. These were assembled using a 3D printed plastic mould inside an aluminium tube for strength. A shim holder, which is also 3D printed, is fitted within the magnet bore and holds iron wires of particular masses that cancel the multipole errors measured using a rotating coil on the unshimmed magnet. A single iteration of shimming reduces error multipoles by a factor of 4 on average. This assembly and shimming method results in a high field quality magnet at low cost, without stringent tolerance requirements or machining work. Applications of these magnets include compact FFAG beamlines such as FFAG proton therapy gantries, or any bending channel requiring a ~4x momentum acceptance. The design and shimming method can also be generalised to produce custom nonlinear fields, such as those for scaling FFAGs. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK007 | |
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| THPIK008 | Beam Dynamics for the ThomX Linac | 4121 |
| SUSPSIK090 | use link to see paper's listing under its alternate paper code | |
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| We report the results of a recent beam dynamics study that has led to promising working points for the split ThomX photoinjector. ThomX is a back-scattering Thomson light source that will use S-band electron Linac with an energy of 50 MeV to produce 45 keV high X-rays flux (1011 - 1013 ph/s), by means of collision between electron bunches and laser pulses, in the energy range from 45 keV to 90 keV. Since Thomx has been conceived to maximise the average X-rays flux in a fixed bandwidth, the high rate electron-photon collisions impose a linear accelerator combined with a storage ring. The high performances of the accelerator are largely affected by the high quality of the electron beam at the interaction point in the ring. Beam specifications should be achieved at the interaction point to the extent that 1 nC, 50 nA average current per bunch with normalised rms transverse emittance less than 5 mm and around 0.3% energy spread, at the end of the linac. The beam dynamics along the linac has been studied to demonstrate the capability of the accelerator to meet the requirements for the high brightness electron beam using an RF photoinjector configuration. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK008 | |
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| THPIK012 | The Magnets of BERLinPro: Specification, Design, Measurement and Quality Analysis | 4124 |
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Funding: Work supported by grants of Helmholtz Association VH-NG-636 and HRJRG-214 A total of 77 magnets form the magnetic lattice of the BERLinPro energy recovery linac prototype: 1+8+8 dipole magnets of three different types, 12+40 quadrupole magnets of two different types and 8 sextupole magnets have been produced by BINP. After the design phase, magnets production started in 2015, measurements and delivery took place in 2016, first assembly stage was finished in 03/2017. The motivation for the magnet specification and a summary of the basic design is given in this paper. Select-ed measurement data from the final acceptance tests are presented and analysed to ensure the magnet quality. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK012 | |
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| THPIK013 | Renewal of Bessy Ii Rf System - Solid State Amplifiers and Hom Damped Cavities | 4127 |
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| Due to the fact that the klystrons run out of production and due to the aging of the old cavities, a renewal of the RF system was necessary. Solid state based transmitters and HOM damped nc single cell cavities have been installed at the BESSY II storage ring. The parameters of the components, the installation phase and the results to the beam will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK013 | |
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| THPIK014 | Travelling Wave Accelerating Structure for Areal 50 MeV Energy Upgrade | 4130 |
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| AREAL facility development implies energy upgrade to 50 MeV in order to drive a THz free electron laser. To reach this goal, the installation of two 1.6 m long S-Band travelling wave accelerating sections, with nominal accel-erating gradient of 15 MV/m, are foreseen. In this paper the design study of accelerating sections along with the matching performance of RF couplers are presented. The simulations are performed using the CST Microwave Studio. The first results of the accelerating structure proto-type fabrication are discussed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK014 | |
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| THPIK015 | Prototype Results of the ESR Barrier-Bucket System | 4133 |
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| The experimental storage ring (ESR), operated at the GSI facility in Darmstadt, Germany, allows experiments with a variety of ion species. In combination with the existing electron cooler, its RF cavities have been used to demonstrate longitudinal beam accumulation in order to increase the beam intensity. Limitations of the existing narrow-band cavities led to the development of a magnetic alloy (MA) based broad-band cavity for the generation of Barrier-Bucket signals. The application of a pre-distortion method demands high linearity of the driver amplifier and highlights the importance of its selection process. In this contribution, the cavity and amplifier system design is described and data measured at a prototype system are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK015 | |
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| THPIK016 | Status of the SIS100 RF Systems | 4136 |
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| Four different types of RF cavities are realized for the heavy-ion synchrotron SIS100 which is built in the scope of the FAIR (Facility for Antiproton and Ion Research) project. The standard acceleration is performed by ferrite cavities. Barrier bucket cavities will allow a pre-compression of the beam by means of moving barriers. Bunch compressor cavities are used to realize a rotation in longitudinal phase space by 90 degrees, thereby reducing the bunch length. Finally, a longitudinal feedback system reduces undesired beam oscillations. In contrast to the ferrite-loaded accelerating cavities, the last-mentioned three cavity types are based on magnetic alloy (MA) material. Depending on the type of the cavity system, the realization is done by - or in close collaboration with - different industrial companies and institutions. In this contribution, the realization status of all these synchrotron RF systems is summarized. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK016 | |
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| THPIK017 | Field Uniformity Preservation Strategies for the ESS DTL: Approach and Simulations | 4139 |
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| The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4 % (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. This paper presents the approach taken in order to preserve field flatness of DTL Tanks. This strategy required a set of simulations and consequent choices about RF design of DTL cells, RF coupler tuning and compensation, cooling of the DTL cells. Outcomes of these simulations and the experimental verifications of this approach are then explained. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK017 | |
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| THPIK021 | Structural Mechanical Analysis of 4-Rod RFQ Structures in View of a Newly Revised CW RFQ for the HLI at GSI | 4142 |
| SUSPSIK091 | use link to see paper's listing under its alternate paper code | |
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Funding: BMBF Contr. No. 05P15RFRBA The High Charge State Injector (HLI) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, serves as one of the two injector linacs for the UNILAC as well as dedicated injector for the upcoming cw linac project for super heavy element research. As the front end of the HLI is planned to be upgraded for cw operation a newly revised cw capable RFQ structure with an operating frequency of 108 MHz is required. The existent 4-rod structure, which was commissioned at the HLI in 2010, suffers from severe modulated rf power reflections originating from mechanical oscillations of the electrodes that both limit the achievable performance and impede stable operation*. Besides preceding vibration measurements that were done by GSI using a laser vibrometer**, the structural mechanical behavior of the 4-rod geometry was extensively analyzed using ANSYS Workbench. Thereby the crucial mechanical eigenmodes could be identified and their impact on the rf properties was investigated by simulations using CST MWS. A completely newly revised 4-rod RFQ design with optimized structural rigidity was developed of which a 6-stem prototype is currently being manufactured. *P. Gerhard et al., Experience With a 4-Rod CW Radio Frequency Quadrupole, LINAC12, THPLB07 **P. Gerhard et al., In Situ Measurements of Mechanical Vibrations of a 4-Rod RFQ at GSI, LINAC14, TUPP057 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK021 | |
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| THPIK022 | Measurements of High-Order Magnetic Field Components of Permanent Quadrupole Magnets for a Laser-Plasma-Driven Undulator X-Ray Source | 4145 |
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| Laser wakefield acceleration as a novel source of high-energy electron beam is a prominent candidate to drive a next generation of compact light sources. For applications, the electron beam needs to be captured using quadrupole magnets with extremely high field gradient. It allows to preserve properties of the laser-plasma driven electron beam. We designed and manufactured compact permanent quadrupole magnets providing magnetic field gradient up to 510 T/m at an aperture radius of only of a few mm. The Halbach-type quadrupole magents use 12 NdFeB wedges with a remanent magnetic field of 1.2 Tesla. We measured the magnetic field of the permanent magnet quadrupoles using the pulsed-wire and rotating-coil methods. Here, we present an analysis of the magnetic field quality and, in particular, the integrated field gradient and high-order field components. We further discuss the influence of the field imperfections on the electron beam quality and its consequences for application in the transport line of a laser-plasma-driven undulator X-ray source. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK022 | |
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| THPIK023 | Concept of the High Power RF Systems for MESA | 4147 |
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Funding: work supported by DFG under the cluster od Excellence PRISMA, EXC 1098/2014 The Mainz Energy-recovering Superconducting Accelerator (MESA) is currently designed and built at the Institut für Kernphysik (KPH) at Johannes Gutenberg-Universität Mainz. The main accelerator incorporates four superconducting cavities of the TESLA type, while the preaccelerator MAMBO (Milliampere Booster) is a room temperature linac. The MESA high power RF-systems have to cover a vast power range starting at some 10kW per cavity for the main linac modules and more 50kW per cavity for MAMBO. In this paper we will present the concept of a unified high power RF system for both main accelerator and preaccelertor, based on solid state technology. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK023 | |
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| THPIK027 | Dynamic Behaviour of Fast-Pulsed Quadrupole Magnets for LINAC4 Transfer Line | 4150 |
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| Linac4, recently built at CERN, is a linear normal conducting accelerator for negative hydrogen ions (H−). A new transfer line will link Linac4 to the Proton Synchrotron Booster. This transfer line includes 21 quadrupole magnets characterized by fast excitation cycles, which make accurate magnetic measurements challenging. This paper describes the method used for the measurement, which is a combination of techniques based on rotating and fixed search coils. We show how these instruments can be used in a complementary way to derive information on different aspects of the magnetic behaviour of these quadrupoles, such as the impact of hysteresis and dynamic eddy current effects. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK027 | |
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| THPIK029 | THE RF CAVITY FOR THE INDUS-2 STORAGE RING | 4154 |
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| A new Elettra-type cavity has been delivered to the Raja Ramanna Centre for Advanced Technology (RRCAT) Indus-2 facility. This cavity is the very same of those already installed several years ago with some optimization of the cooling channels. It is the Elettra-type cavity, normal conducting copper single cell but resonating at 505.8 MHz. The cavity description, the full characterization of the accelerating mode (L0) and high order modes (HOM) and the acceptance tests are presented in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK029 | |
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| THPIK030 | THE RF CAVITY FOR THE SESAME FACILITY | 4158 |
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| SESAME is a 2.5 GeV Synchrotron Light Source under commissioning in Allan (Jordan). It will be the first inter-national research centre in the Middle East [1]. It is a cooperative venture with support provided by several international organizations and scientific laboratories. Elettra-Sincrotrone Trieste (Italy) is among them. In the framework of the collaboration agreement among SESAME (Jordan), INFN (Italy) and Elettra-Sincrotrone Trieste, four 500 MHz normal conducting (NC) copper cavities have been built and commissioned at Elettra and then successfully installed in the SESAME storage ring. The cavities properties, their fabrication process, their characterization at low and high RF power is presented here. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK030 | |
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| THPIK032 | Installation and Low Power Test of IFMIF-EVEDA RFQ at Rokkasho Site | 4162 |
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| The IFMIF-EVEDA RFQ is composed of 18 modules for a total length of 9.8 m and is designed to accelerate the 125 mA D+ beam up to 5 MeV at the frequency of 175 MHz. The RFQ is subdivided into three Super-Modules of six modules each. The Super-Modules were shipped to Rokkasho (Japan) at the beginning of 2016, pre-assembled 3 m far from the final location and tuned to reach target field flatness requirements. Just after conclusion of injector commissioning, the tuned RFQ was disassembled, moved and reassembled in the final location. After confirmation that field flatness was not affected by this movement, high power couplers were installed and tuned and all the structure was baked. Assembling, tuning and coupling results will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK032 | |
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| THPIK033 | RF-Mechanical Design and Prototyping of the SPES RFQ | 4166 |
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| The SPES RFQ is designed in order to accelerate beams in CW with A/q ratios from 3 to 7 from the Charge Breeder through the MRMS and the selection and injection lines up to the MEBT. RFQ is composed of 6 modules about 1.2 m long each. Each module is basically composed of a Stainless Steel Tank and four OFE Copper Electrodes (obtained by brazing of two subassemblies in order to spare material). A copper layer is electrodeposited on the tank inner surface and a spring joint between tank and electrode is used in order to seal the RF. In this paper the main result of the design of the RFQ (with particular focus on the RF-mechanical aspects and thermo-structural calculations), the RFQ prototyping strategy as well as the construction and assembly procedure of RFQ modules are described. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK033 | |
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| THPIK035 | Rf Properties of a 175 MHz High-Q Load Circuit | 4169 |
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| For an RF input coupler test, a 175MHz high-Q load circuit based on a 6 1/8 in. co-axial waveguide was developed. This circuit consists of the RF input coupler, a trombone-type phase shifter and a stub tuner. The coupler with a loop antenna and the stub tuner are located in edges of the circuit, the loop antenna and the tuner work for a short plate. When RF input power is injected into the circuit, a high-voltage standing wave is excited by adjusting the tuner. The power of standing wave required for the tests is also accumulated due to its low resistive loss. At the operation frequency of 175 MHz, the resistive loss of 0.046ohm is measured and an equivalent RF power of 200 kW is accumulated by the RF input power of 740 W. In this circuit, the bandwidth is narrow to be ±5 kHz in S11 parameter of less -20 dB, but the equivalent RF power of 200 kW-14 sec CW could be achieved after sufficient RF aging. Using this high-Q load circuit, all the fabricated 9 couplers were successfully tested for RF contact defects, unnecessary low-Q value and extraordinary outgassing. This article describes these RF properties in detail. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK035 | |
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| THPIK036 | Design Study of Damped Accelerating Cavity Based on the TM020-Mode and HOM Couplers for the KEK Light Source Project | 4172 |
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A novel damped-cavity scheme was recently proposed by Ego et al.*. In this design, TM020 resonant mode is used for beam acceleration. Power of higher-order (or lower-order) modes are extracted through cylindrical slots which are placed at the position where the magnetic fields of HOMs are strong while that of TM020 mode is zero. Extracted powers are absorbed by lossy ferrites. In this scheme, excellent HOM damping is possible while occupying less space of the straight section in storage rings. We propose in this paper an alternative design which is based on the same TM020 mode but with rod-type HOM couplers. The rod-type HOM couplers are placed where the electric fields of HOMs are strong while that of TM020 mode is zero. In this scheme, openings needed for HOM extraction can be made smaller, which is desirable for stiffening the mechanical structure of the cavity. Potential use of lossy dielectric materials is another merit. We present external Q-values of HOMs that can be achieved in this scheme, as well as an effect of HOM couplers on the TM020 mode. Our current study is directed to a 1.5 GHz higher-harmonic cavity for the proposed KEK Light Source project**.
* H. Ego et al., in Proceedings of the 11-th Annual Meeting of Particle Accelerator Society of Japan, Aug. 9-11, 2014, MOOL14 [in Japanese]. ** K. Harada et al., IPAC2016, THPMB012. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK036 | |
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| THPIK037 | Simulation Study of Normal-Conducting Double RF System for the 3-GeV KEK Light Source Project | 4176 |
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For the proposed 3-GeV KEK Light Source (KEK-LS) project*, a double RF system using 500-MHz accelerating and 1.5-GHz third-harmonic cavities is under consideration. To mitigate intrabeam scattering due to ultra-low emittance, the bunch length will be elongated using the harmonic cavities which is based on the TM020 resonant mode. An accelerating cavity based on this mode was first proposed by Ego et al.**, and we found it very suitable for the harmonic cavities due to the following reasons: 1) it has high unloaded-Q and high stored electromagnetic energy which result in the reduction of transient beam-loading effect due to bunch gaps, and 2) efficient damping of higher (or lower) order modes is possible. Our investigations based on numerical simulations predicted the bunch elongation by a factor of 3.1 when realistic bunch-gaps were assumed. To improve the bunch elongation further, we also proposed to compensate the transient beam loading with two realistic measures: 1) compensation of rf voltages due to feedforward technique, and 2) compensation using a separate rf cavity. We will present our study on the double rf system based on numerical simulations.
* K. Harada et al., IPAC2016, THPMB012. ** H. Ego et al., Proceedings of the 11-th Annual Meeting of Particle Accelerator Society of Japan, Aug. 9-11, 2014, MOOL14 [in Japanese]. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK037 | |
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| THPIK038 | Design of a 100 kW Solid-State RF Pulse Amplifier with a TE011 Mode RF Combiner at 476 MHz | 4180 |
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| Solid-state RF amplifiers, which have long lifetimes and small failures, are the recent current of high-power RF sources for particle accelerators. Hence, we designed a 100 kW solid-state amplifier with a TE011 mode cavity (Q0=100, 000) power combiner with extreme low-loss operated at 476 MHz and a 6 us pulse width. Developing this amplifier is for replacement of a high-power amplifier using an induction output tube, IOT, in the X-ray free-electron laser, SACLA. In SACLA, highly RF phase and amplitude stabilities of less than 0.01 deg. and 10-4 in rms are necessary to stable lasing within a 10 % intensity fluctuation. The amplifier comprises a drive amplifier, a reentrant cavity RF power divider, 100 final amplifier modules with a 1 kW output each and a TE011 mode cavity combiner. Water-cooling within 10 mK and a DC power supply with a noise of less than -100 dBV at 10 Hz for the amplifier is necessary to realize the previously mentioned stabilities. Based on the experimental results of a test amplifier module and test combiner cavities, possibility to realize the above-mentioned specifications is large. We report the detail and a part of the performance of the 100 kW amplifier. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK038 | |
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| THPIK039 | Multipactor Problem of J-PARC SDTL | 4184 |
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| We have suffered from multipactor problem of some SDTL after the Great East Japan Earthquake. As a designed operating rf power of the SDTL is in the multipactor region, we had to operate at higher power of the designed one. From the result of the simulation and the observation of the SDTL cavity, it became clear that the multipactor occurred on the inner surface of the cavity. We think that one of the cause of the maultipactor is the contamination on the inner surface of the cavity, we performed the cleaning of the inner surface of the cavity by using acetone. The cleaning was very effective and the multipactor region was reduced dramatically or disappeared. The multipactor problem has not occurred since then. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK039 | |
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| THPIK041 | The RF System of the SESAME Storage Ring | 4187 |
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| SESAME the Synchrotron Radiation Light Source in Allan (Jordan) consists of a 22 MeV Microtron, an 800 MeV Booster Synchrotron (originally from BESSY I, Berlin, Germany) and a 2.5 GeV Storage Ring (new de-sign). The RF system consists of four 500 MHz ELET-TRA cavities powered by four 80 kW Solid State Ampli-fiers whereas the first amplifier is produced by SOLEIL and the other three are produced by SIGMA-PHI. The RF plant is controlled by the digital Low Level Electronics from DIMTEL. The system has been installed end of 2016. This report describes the setup of the facility and the results of the commissioning. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK041 | |
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| THPIK042 | The Magnetic Measurement of Conventional Magnets for Electron Beam Accelerator of Northwest Institute of Nuclear Technology | 4190 |
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| The project of electron beam accelerator is worked together completed by NINT (Northwest Institute of Nuclear Technology) and IHEP (Institute of High Energy Physics, China). Conventional magnet of the project includes a total of three dipole magnets, four quadrupole magnets, six solenoid magnets, and four correction magnets. All of magnets to complete the measurement by IHEP hall measuring equipment. The integrated magnetic field measurement of the arc-shaped dipole magnet requires simultaneous movement by the X-axis and the Z-axis, using Labview software written a new measurement procedure, the new measurement procedure has been completed by setting the measuring angle and the measuring radius. All measurement results of conventional magnets have reached the physical design requirements, and each magnet were carried out more than twice the measurement, the reproducibility of the measurement results are better than one-thousandth, fully meet the design claim of NINT. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK042 | |
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| THPIK043 | Design and Optimization of a 2MeV X-Band Side Coupled Accelerating Structure | 4193 |
| SUSPSIK093 | use link to see paper's listing under its alternate paper code | |
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| An X-band bi-period side-coupled accelerating structure has been designed in this paper. The structure's working frequency is 9.3GHz. '/2 mode is chosen for the structure's stability. There are 11 accelerating cells, the first 5 work as non-light velocity part while the other 6 work as light velocity part. After CST simulation, the coupling constant between accelerating cells and coupling cells is 5%, efficient shunt impedance is 142M'/m. For the beam dynamic analysis, the particle energy is selected to be 2 MeV and the peak current is 60 mA for the radiation dosage limits by national standard. After Pamela optimization, the particle's capture efficiency is more than 30%. To feed power into the structure, a coupler is designed in the middle of the structure and the coupling coefficient is 1.4. The structure is manufactured and the measurement result accords well with designing value. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK043 | |
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| THPIK045 | Design of a C-band Travelling-wave Accelerating Structure at IHEP | 4196 |
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| A C-band travelling wave accelerating structure has been developed at IHEP. The structure is a constant gra-dient type and operating with a 3'/4 mode. The total length of the structure is 1.8-meters long with 85 regular cells and two coupler cells. 2D program Superfish is used to optimize the cavity shape and the iris size. The wall cells are rounded for it can improved the Q value for about 10%. The cell irises have an elliptical profile to minimize the peak surface electric fields. In order to compatible with the compact of the short-range wake field on the beam dynamics, the average iris radius is 7.15 mm. The group velocity of the designed structure is from 2.8% to 1.4%. Between the rectangular waveguide and the accelerating structure, magnetic coupling is adopted. The coupled cavity is racetrack type in order to minimize the asymmetry in the coupler. Kyhl's method is used to match the input and output coupler. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK045 | |
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| THPIK046 | Design, Fabrication and Cold Test of a C-Band Barrel Open Cavity Pulse Compressor | 4200 |
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| The first prototype of the C band barrel open cavity (BOC) pulse compressor has been manufactured by the Institute of High Energy Physics (IHEP), Beijing, which is used to test the brazing process and the RF properties of the structure at low power. The whispering gallery mode TM6, 1,1 with an unload Q of 100, 000 was adopt to oscillate in the cavity, and the coupling factor was optimized to achieve the highest power gain. This paper mainly deals with the RF design, mechanical design and cold test of the C band BOC pulse compressor. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK046 | |
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| THPIK048 | Design of Rapid Tuning System for a Ferrite-Loaded Cavity with Heavy Beam Loading | 4203 |
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| A high power, broadband and rapid frequency sweeping RF system was developed to satisfy the demand of China Spallation Neutron source (CSNS)/ Rapid Cycling Synchrotron (RCS). The cavity tuning is the key issue which has great impact on the performance of the whole RF system. In order to satisfy the requirement of cavity dynamic tuning caused by the nonlinear characteristics of the ferrite material, some new technologies were developed and applied. In this paper, the overall design of the tuning system will be introduced. The ensuing discussion will be focused on the choice of different types bias current supplies, the control algorithm of LLRF system and the beam loading compensation issues. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK048 | |
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| THPIK049 | High Power Conditioning of the DTL-1 for CSNS | 4207 |
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| The RF tuning of the first DTL tank for the China spalla-tion neutron source was finished leading to a stabilized-uniform accelerating field. After the installation of the DTL-1 in the linac tunnel, the high power conditioning was carried out deliberately. Consequently a peak RF power of 1.6MW with 25Hz repetition rate and 650'sec pulse width was put into the tank stably. A 3MeV H− ion was injected into the DTL-1 and was successfully accel-erated to 21.6MeV with almost 100% transmission. Dur-ing the operation, The DTL-1 tank worked stable in the design power level. The conditioning details will be pre-sented in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK049 | |
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| THPIK050 | Measurement and Tuning of the RF Field for the CSNS DTL | 4210 |
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| The CSNS DTL accelerates negative hydrogen ions from 3MeV to 80MeV with resonant frequency of 324MHz and peak current of 15mA. The CSNS includes four DTL cavities with diameter of 56.6cm and each length of 9 meters. RF properties research and measurement have been done to make sure the design and manufacture validate for beam operation. A new automatic system has been developed for measuring field distribution. The secondary derivation method is used to calculate the amount of the tuners to tune axial field flatness. The tilt of TS curve is used to judge the gap between the post couplers and drift tubes to achieve stability. At last the tanks have good flatness and strong stabilization, the field deviation is 2% with the standard deviation of 0.96%, and the maximum TS parameter is 65%/MHz. After the low power RF tuning experiment, the four tans have been installed in the tunnel, and have gotten good results of high power test and beam acceleration experiment. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK050 | |
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| THPIK054 | The X-Band Pulse Compressor for Tsinghua Thomson Scattering X-Ray Source | 4214 |
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| An X-band (11.424 GHz) high-power RF station is being built for Tsinghua Thomson scattering X-ray Source (TTX). The station aims to feed several X-band accelerating structures working at a high gradient of 80 MV/m. An X-band pulse compressor is designed to compress the RF pulse from 1.5 us to 100 ns and to generate more than 250 MW peak power from a 50MW klystron. This pulse compressor implements a resonate cavity housing the HE11-mode as the energy storage cavity, with a high quality factor Q of more than 105. The detailed design of the high-Q cavity as well as the dedicate couplers of this pulse compressor are present in this work. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK054 | |
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| THPIK055 | Power-Conditioning Cavity Design and Measurement of the Coaxial Coupler for the Injector of XiPAF Project | 4218 |
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| For the RF high power conditioning on coaxial power couplers of the XiPAF (Xi'an Proton Application Facility), the RF high power-conditioning cavity was designed and manufactured. The cavity consists of a rectangular reso-nant cavity with two ports, which one is connected with input coupler from RF power source and the other one is connected with output coupler, and a tuner. The tuning frequency range could cover 325 (+0.5, -9.5) MHz. The measured Q factors are matched with the design results generally. But the S-parameter is not ideal compared to the simulation. This paper will present the design and low power measurement results of the cavity | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK055 | |
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| THPIK056 | Design of a C-Band High-Efficiency Multi-Beam Klystron | 4221 |
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| A multi-beam klystron at 5.712GHz has been designed with efficiency of more than 80%. It can generate a pulse with output power of about 3MW and a pulse length of 5 us. Space charge effect and large signal theory, which both increase the accuracy theoretically, are considered in the simulation. A series of parameters of cavities are given after optimizing, including the frequency, R/Q, Q0 and Qe. This paper describes the beam dynamics design of the klystron as well as a preliminary machenical design. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK056 | |
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| THPIK057 | Development of a High-Power X-Band RF Rotary Joint | 4224 |
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| RF rotary joints allow the independent movement be-tween the RF power source and the accelerating tube of a linear accelerator (linac). In this paper, the design of a compact X-band (9.3 GHz) high-power RF rotary joint is presented. Simulation results illustrate that RF parameters (the scattering matrix) of this rotary joint keep stable in the arbitrary rotation angle. The maximum return loss is about -30 dB, the insert loss is less than 0.11 dB, and the variance of output phase shifts is below 1 degree while rotating the joint. RF measurement on the rotary joint using Vector-Network analyser is also conducted and presented in this paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK057 | |
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| THPIK058 | Development of a S-Band Pulse Compressor | 4227 |
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| We designed and fabricated a pulse compressor for S-band high power test stand at Tsinghua University. This pulse compressor is made up of a sphere resonant cavity with quality factor of 100000 and a rf polarizer. It has the ability of compressing a pulse from 3.6 us to 300 ns with the power gain of 7. A short description of the pulse compressor is presented, together with the RF design and low level RF measurement. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK058 | |
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| THPIK059 | Experimental Study on PM-AM Method in Pulse Compression System | 4230 |
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| We experimentally demonstrate the PM-AM method (Phase Modulation to Amplitude Modulation) at the S-band high power test stand, which consists of two S-band klystrons, a SLED type pulse compressor and two high power stainless steel RF loads, in Tsinghua University. A LLRF (low level RF) system has been developed to modulate the phases of the two klystrons in real time such that pulse compressor could generate a flat output pulse. Experimental results presents that the efficiency of the pulse compression system is 45% and the power gain is 2.9. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK059 | |
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| THPIK060 | Tuning of an S-Band 10 MeV Traveling-Wave Accelerating Structure with a Non-uniform Section | 4233 |
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| A tuning method of nonuniform travelling wave structures has been developed based on non-resonant perturbation measurement at Tsinghua University. The filed distribution is normalized with the shunt impedance and attenuation of each cell. Then their internal reflection can be deduced and corrected by cavity deforming. This method has been applied to an S-band 10 MeV travelling wave structure successfully. In this paper, the detailed tuning method and cold test results will be presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK060 | |
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| THPIK061 | 3D Model Analysis of Cavity for CSNS DTL | 4236 |
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| An Alvarez-type Drift tube linac (DTL) was utilized to accelerate an H− ion beam from 3 MeV to 80 MeV of China Spallation neutron source (CSNS). RF field profile is always deviate from the design curve due to errors in fabrication and assembly of the structure cells, thus RF tuning of DTL is necessary. CSNS DTL operates in zero mode and has long tank, so accelerating field of which is unstable, this problem was solved through adding post couplers at the both side of cavity wall. In order to speed up the schedule of DTL low power RF tuning, we analyzed the operating mode, field flatness with slug tuners, field stabilization with post couplers by CST Micro wave studio (MWS) mainly with eigenmode solver in advance. Considering saving the computer memory and increasing the calculation speed, we divided each tank model into three short units. Slug tuner depth and PC-DT gap of DTL-1 and DTL-3 by simulation were shown which improved the efficiency of CSNS DTL RF tuning. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK061 | |
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| THPIK063 | The RF System of Infrared Free Electron Laser Facility at NSRL | 4239 |
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Funding: The Natural Science Foundation of China An infrared free electron laser light source (IRFEL) is being constructed at National Synchrotron Radiation Laboratory, which could be used in the study of far infrared detection, light dissociation and light excitation. The accelerator of IRFEL deliver a average current 300 A electron beam at 15~60 MeV, the energy spread is less than 240 keV, and the emittance is less than 30 mm*mrad. IRFEL is consisted of two optical resonator system, which could create 2.5~50 um, 40~200um infrared laser respectively. The design of IRFEL RF system is introduced, the recent progress of prebuncher, buncher, frequency distribution, accelerator and DLLRF system are also present in this paper. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK063 | |
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| THPIK064 | Beam Lifetime Analysis of HLS-II Storage Ring | 4242 |
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Beam lifetime is one of the important parameters of electron storage rings, which can describe the particle loss rate quantitatively and is restrict by quantum lifetime, beam-gas scattering and Touschek effect. The upgrade project of Hefei light source, named HLSII, has greatly improved the performance of the light source. The beam lifetime has been maintained at more than 5 hours. In this paper, a combined analysis method is derived by the analysis of the beam lifetime, and the method is applied to the HLSII storage ring. The experimental results show that this method is simple and reliable for the analysis of the Touschek lifetime and beam-gas scattering lifetime.
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK064 | |
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| THPIK065 | Reliability Anlysis of 20kw Solid-State Amplifiers for Ciads | 4245 |
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| CIADS will apply the solid-state amplifier. 20KW solid-state amplifiers are the basis of RF systems. This talk model 20KW solid-state amplifiers with reliability block diagram(RBD). Through simulation, we find that the reliability function relative to redundancy approximates logarithm, but cost is linear growth. There is an optimal solution between redundancy and cost. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK065 | |
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| THPIK067 | A C-Band Compact Spherical RF Pulse Compressor for the SXFEL Linac Energy Upgrade | 4248 |
| SUSPSIK094 | use link to see paper's listing under its alternate paper code | |
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| A new compact C-band (5712 MHz) spherical RF pulse compressor has been designed for Shanghai Soft X-ray Free Electron Laser (SXFEL) facility energy upgrading at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS). This pulse compressor contains one high Q0 spherical RF resonant cavity which works on two TE113 modes and a novel coupler. As there is only one storage cavity, this pulse compressor can be much smaller than the traditional SLED. With the coupling coefficient 4.9, the average power gain can be as high as 3.8. In this paper, the scheme of the C-band spherical pulse compressor and RF design are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK067 | |
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| THPIK068 | High Power Test of SINAP X-Band Deflector at KEK | 4251 |
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| A crucial RF structure used for bunch length measurement for Shanghai X-ray Free Electron Lasers (SXFEL) at the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Science [1]. The design, fabrication, measurement and tuning have been completed at SINAP [2], and the high power test was carried out at Nextef of KEK with international collaboration. This paper presents the RF conditioning process and test results. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK068 | |
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| THPIK070 | Localization of RF Breakdown Point in a Coaxially Loaded LINAC Cavity | 4254 |
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| Here we report how the RF breakdown point (RFBP) can be localized in a coaxially loaded linac cavity with just the forward and the reflected power signal. The cavity uses 4 load cells instead of output coupler to absorb remanent power, so no transmitted power signal could be recorded. We propose two methods to analyze the measured signals and localize the RFBP. One method focuses on the time delay of the two signals while the other one focuses on the amplitude. Quantitative analysis showed the two methods were well consistent with each other and indicated the RFBP located at the end of the linac cavity. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK070 | |
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| THPIK072 | Development of High Power RF Amplifier System for the KBSI RFQ | 4257 |
| SUSPSIK108 | use link to see paper's listing under its alternate paper code | |
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| KBSI (Korean Basic Science Institute) has been developed a compact accelerator system for generation of fast neutron by 2.7 MeV/u of lithium beam. The facility consists of 28 GHz SC-ECR ion source, LEBT, RFQ and DTL. The developed RFQ accelerator provides lithium ion beam from 12 keV/u to 500 keV/u with 98.88 % of high transmission rate at 165 MHz of operation frequency. RF power system for RFQ accelerator has been developed to provide sufficient RF power into RFQ cavity. which consists of LLRF system for control, 5 KW of SSPA as IPA, tetrode tube amplifier as FPA, coaxial transmission line and circulator for protection from reflection power provides 100 kW at operation frequency with CW mode, In this paper, we discuss about development of RF system and performance test in detail. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK072 | |
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| THPIK073 | Development of RFQ for BNCT Accelerator | 4260 |
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| A accelerator for Boron Neutron Capture Therapy (BNCT) based on proton linac has been developed as a domestic project. The accelerator system consists of duo plasmatron as an ion source, low energy beam transport (LEBT), radio frequency quarupole (RFQ) accelerator, drift tube linac (DTL). In order to achieve beam power of 50 kW, the required beam intensity and energy are 50 mA and 10 MeV, respectively. Since high duty rate provides high efficient medical treatment, the design of the cw RFQ has been investigated to accelerate proton beam from 50 keV to 3 MeV with beam intensity of 60 mA. In this paper, beam dynamics and design of the RFQ are presented in detail. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK073 | |
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| THPIK078 | 1.5 GHz Cavity Design for the CLIC Damping Ring and as Active Third Harmonic Cavity for ALBA | 4263 |
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| In a collaboration framework between CERN and ALBA, we are designing a normal conducting active 1.5 GHz cavity which could serve as main RF system for the Damping Ring of CLIC and as an active third harmonic cavity for the ALBA Storage Ring. The third harmonic cavity at ALBA will be used to increase the bunch length in order to improve the beam lifetime and increase the beam stability thresholds. The main advantage of an active third harmonic cavity is that optimum conditions can be reached for any beam current. This paper presents the preliminary design of this cavity: an active, normal conducting cavity tuned at 1.5 GHz based on the 500 MHz European Higher Order Mode (HOM) damped normal conducting with nose cones using ridged circular waveguides for HOM damping. Electromagnetic simulations, mechanical and thermal stress analysis will be presented together with the calculations on beam stability improvement due to the third harmonic system. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK078 | |
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| THPIK079 | Developments and Measurements Done at ALBA Magnetic Measurements Laboratory Along 2016 | 4266 |
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| Along 2016, ALBA magnetic measurements laboratory has measured magnets for a number of facilities that are being built over the world. Their measurement has been a challenge in terms of improving the methodologies of fiducialization and data analysis, since we have to accommodate to the different set of magnets characteristics and specifications. Especially relevant has been the measurement of closed structures using a conventional Hall probe bench, making the measurement in two steps and relying on alignment accuracy to merge both measurements. In this paper we enumerate the different projects in which ALBA has collaborated, and we remark the method for aligning the quadrupoles to the rotating coil, as well the methodology used to measure closed magnets in two steps with the conventional Hall probe bench. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK079 | |
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| THPIK080 | Magnetic Performance of the New ALBA Magnetic Measurements Bench for Closed Structures | 4269 |
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| ALBA has designed and built a new magnetic measurement bench for closed structures, presented elsewhere. This bench has been fully built in-house and has been magnetically characterized at ALBA, showing excellent performance in terms of repeatability and accuracy. In the case of homogeneous fields, the accuracy reaches 10 microTesla, and in the case of undulators characterization, the accuracy of period determination reach 0.5 microns and the field accuracy is 60 microTesla. After this characterization, the bench has been moved to CIEMAT premises, and has been used to magnetically characterize the superconducting magnet of the AMIT cyclotron. In this paper we present the results of magnetic characterization of the bench as well as the first results of cyclotron measurements. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK080 | |
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| THPIK081 | Design and Construction of a High-Gradient RF Lab at IFIC-Valencia | 4272 |
| SUSPSIK096 | use link to see paper's listing under its alternate paper code | |
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| The IFIC High-Gradient (HG) Radio Frequency (RF) laboratory is designed to host a high-power infrastructure for testing HG S-band normal-conducting RF accelerating structures and has been under construction since 2016. The main objective of the facility is to develop HG S-band accelerating structures and to contribute to the study of HG phenomena. A particular focus is RF structures for medical hadron therapy applications. The design of the laboratory has been made through collaboration between the IFIC and the CLIC RF group at CERN. The layout is inspired by the scheme of the Xbox-3 test facility at CERN, and it has been adapted to S-band frequency. In this paper we describe the design and construction status of such a facility. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK081 | |
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| THPIK082 | Quadrupole Magnet Design for the ESS MEBT | 4276 |
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Funding: Consortium ESS Bilbao ESS Bilbao is responsible for the design and fabrication of the ESS MEBT as an In-Kind contribution. The MEBT includes a focusing lattice with 11 quadrupole magnets with different operational gradients, but fabricated from the same model to simplify manufacturing and save costs. The magnet is designed with a 20.5 mm aperture radius to generate focusing fields of up to 2.74 T and also includes two additional steering coil systems assembled around yoke return arms to produce vertical and horizontal dipole fields up to 20 G·m. The magnet model, which fabrication starts in 2017, is here introduced. Magnetic, thermoelectric and dimensional studies are performed and results compared to specifications. Suitable transfer functions for magnet operation and magnetic fields for a doublet system with a BCM magnetically shielded placed between the two magnets are presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK082 | |
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| THPIK083 | Mechanical Fabrication of ESS-Bilbao RFQ | 4279 |
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| The fabrication of the first segment of ESS-Bilbao's RFQ has started in 2016. The segment, of about 800 mm in length, is an assembly of 4 elements: two major vanes and two minor ones. The assembly will be done by making use of carefully-designed vacuum polymeric gaskets instead of brazing. Electron beam welding has been used during fabrication of the vanes. Apart from conventional CAD systems, a home-made tool for vane modulation solid generation has been successfully used. Machining process from copper blocks to final elements is described in detail. Also, the software tools created to assess the quality of the vanes by analyzing the metrology measurements, particularly of the modulation, are described in the paper. In order to test and validate the chosen vacuum strategy, an aluminum model using the same gaskets as the final model was built and tested. Results will also be presented. The fabrication of the first segment is expected to end up in early 2017, so assembly, segment alignment and vacuum tests with the real device will also be included in the paper. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK083 | |
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| THPIK084 | Results from the 704 MHz Klystron and Multi-beam IOT Prototypes for the European Spallation Source | 4282 |
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| The European Spallation Source, currently under construction in Lund, Sweden, will contain 155 RF sources for proton beam acceleration. Of these, 120 are at 704 MHz. Each cavity will be powered by individual RF sources. The nominal beam pulse width is 2.86 ms and the RF systems are being specified for a pulse width up to 3.5 ms to allow for ramping and time for regulation. The repetition frequency is 14 Hz which results in 5% duty. The 704 MHz linac is divided into two sections, the medium beta and the high beta cavities. For schedule reasons, the medium beta linac, 36 RF sources, will be based on 1.5 MW pulsed power klystrons and the high beta section, 84 RF sources, is planned to be operated with 1.2 MW multi-beam IOTs. ESS ordered three klystron prototypes designed for the ESS parameters from different supplies and two multi-beam IOT technology demonstrators under two different contracts. We present the specifications for the amplifiers and the results of the klystron prototypes and report the result of the first 1.2 MW multi-beam IOT prototypes. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK084 | |
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| THPIK086 | Design and Implementation of Stripline Feedback Kickers in the MAX IV 3 GeV Ring | 4285 |
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| 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. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK086 | |
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| THPIK087 | A Waveguide Overloaded Cavity Kicker for the MAX IV Bunch-by-Bunch Feedback System | 4289 |
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| The higher-order modes (HOMs) in the main and the 3:rd harmonic cavities are driving longitudinal coupled-bunch mode instabilities (CBMIs) in the MAX IV 3 GeV storage ring. This far, negative feedback has been applied in the longitudinal plane by a stripline kicker at lower ring currents. However, the maximum longitudinal feedback voltage provided by the stripline is rather weak, and a waveguide overload cavity was therefore designed in order to suppress CBMIs at higher ring currents as well. Due to the long bunch length in the MAX IV storage rings, a relatively low center frequency of 625 MHz is selected. The new cavity kicker has been manufactured, and will be installed in the 3 GeV ring during the summer shut-down of 2017. In this paper, the RF and mechanical design of the cavity is presented. Simulation results are also compared with measurements of the manufactured cavity. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK087 | |
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| THPIK088 | A Compact 10 kW Solid-State RF Power Amplifier at 352 MHz | 4292 |
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| A compact 10 kW RF power amplifier at 352 MHz was developed at FREIA for the European Spallation Source, ESS. The specifications of ESS for the conception of amplifiers are related to its pulsed operation: 3.5 ms pulse length and a duty cycle of 5\%. The realized amplifier is composed of eight kilowatt level modules, combined using a planar Gysel 8-way combiner. The combiner has a low insertion loss of only 0.2 dB, measured at 10 kW peak power. Each module is built around a commercially available LDMOS transistor in a single-ended architecture. During the final measurements, a total output peak power of 10.5 kW was measured. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK088 | |
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| THPIK090 | 352 MHz Tetrode RF Stations for Superconducting Spoke Cavities | 4296 |
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| Two 352 MHz tetrode based RF stations for pulsed operation have been developed at the FREIA Laboratory, Uppsala University to validate the design and performance as RF source for the Spoke cavities in the first superconductive stage of the European Spallation Source(ESS) linear accelerator. The stations use dual TH595 tetrodes rated at 210 kW peak-power to provide a total power of 400 kW with a maximum pulse duration of 3.5 ms at 14 Hz repetition rate. Each tetrode is fed by a 10 kW solid state amplifier and the station is monitored by an internal control system with complete remote access. Extensive measurements have been performed on the RF performance, the power supplies as well as on the interlock systems. To conform to the specifications, special attention must be given for the response time of the tetrode power-supplies to acquire good quality RF output pulses. For the interlock system any shut-down condition due to tube malfunctioning or other sources must switch off the station in a controlled manner with minimal damage to any internal circuitry or to the tube itself whilst at the same time provide a fast discharge and cut-off of all relevant power supplies. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK090 | |
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| THPIK092 | Considerations on the Effect of Magnet Yoke Dilution on Remanent Field at ELENA | 4299 |
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The Extra Low Energy Antiproton ring (ELENA) is a small synchrotron constructed at CERN to decelerate antiprotons down to 100 keV and, thus, operated at very low magnetic fields. The CERN magnet group has carried out extensive investigations on accelerator magnets for very low fields, comprising theoretical studies and the construction of several prototype magnets, to ensure that the required field quality can be reached at these very low fields. In the course of this work, experimental investigations [1] led to the initially unexpected observation that dilution of the yoke, i.e. alternating laminations made of electric steel with thicker non-magnetic stainless steel laminations, increases the remnant field. An explanation for this behaviour has already been anticipated in a previous paper [2]. Here, we treat this specific topic in analytical detail. We come to the conclusion that magnet yoke thinning in most practical situations does not improve the field quality at very low field levels, but rather enhances the impact from hysteresis and remanence effects.
[1] L.Fiscarelli, Magnetic measurements on the quadrupoles prototypes for ELENA (PXMQNLGNAP), CERN internal report. [2] D. Schoerling, Case Study of a Magnetic System for low-Energy Machines, PRAB 19, 082401 (2016). |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK092 | |
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| THPIK093 | Blow-Up Due to Intra Beam Scattering during Deceleration in ELENA | 4303 |
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| Intra Beam Scattering (IBS) is expected to be the main performance limitation of the Extra Low Energy Antiproton ring (ELENA), a small synchrotron equipped with electron cooling under construction at CERN to decelerate antiprotons from 5.3 MeV to 100 keV. Thus, the duration of the ramps must not be too long to avoid excessive blow up due to IBS. On the other hand, the bending magnets are C-shaped and the vacuum chambers are without insulated junctions, which are difficult for fully baked machines; thus, the ramps must not be too short. The evolution of transverse and longitudinal emittances along the ramps have been estimated assuming that IBS is the main phenomenon leading to blow-up. The blow-up due to IBS found along the ramps have been found to be acceptable. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK093 | |
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| THPIK094 | Linac4 PIMS Construction and First Operation | 4307 |
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| Linac4, CERN's new H− injector Linac uses PI-Mode Structures (PIMS) for the energy range between 103 and 160 MeV. 180 copper elements for 12 PIMS cavities have been fabricated in a collaboration between CERN, NCBJ and FZJ from 2011 to 2016. The cavities have been assembled, RF tuned and validated at CERN. This paper reports on the results as well as the experience with construction, installation, RF conditioning and first operation with beam. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK094 | |
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| THPIK095 | High Power X-Band Generation Using Multiple Klystrons and Pulse Compression | 4311 |
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| CERN has constructed and is operating a new X-band test stand containing two pairs of 12 GHz, 6 MW klystrons. By power combination through hybrid couplers and the use of pulse compressors, up to 45 MW of peak power can be sent to any of 4 test slots at pulse repetition rates up to 400 Hz. The test stand is dedicated to RF conditioning and testing of high gradient accelerating structures for the CLIC study and also future X-band FELs. Operations have been ongoing for a few months, with initial operation dedicated to control algorithm development. Significant progress has been made in understanding the unique challenges of high power RF combination and phase switching using RF hybrids. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK095 | |
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| THPIK096 | Jitter Measurement to 10ppm Level for Pulsed RF Power Amplifiers 3 - 12GHz | 4314 |
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| Linacs for FEL applications require a low jitter RF path from RF source through pulsed amplifiers, klystron / modulators and cavities. For the SwissFEL project, pulsed solid state power amplifiers of the 500W / 3us class for driving the klystrons were required. For these amplifiers, a stable and reliable interferometer system was developed to measure the residual RF jitter levels to <10 ppm (parts per million) and <10 urad (0.6mdeg) rms. This paper describes the system and gives some measurement results for 3GHz, 5.7GHz and 12GHz amplifiers. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK096 | |
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| THPIK097 | High Power Tests of a Prototype X-Band Accelerating Structure for CLIC | 4318 |
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Funding: Partially funded by SNF FLARE grant 20FL20147463 We present the design, construction and high-power test of an X-band radio-frequency accelerating structure, built as a prototype for the CERN LInear Collider (CLIC) study. X-band structures have been attracting increasing attention in recent years with applications foreseen in the domains of compact free electron lasers, medical accelerators and as diagnostics for ultra-short (femtosecond) electron bunches (when used in deflecting mode). To date, the main motivation for developments in this field has been as accelerating structures for linear colliders such as CLIC. In the context of a CERN/PSI collaboration we have built a prototype structure based on an existing CERN design, but with some modification, and following, as closely as possible, the realization and vacuum brazing techniques employed in the production of the C-band structures for the Swiss Free Electron Laser, SwissFEL. We will present the basic design of the structure and describe the fabrication process. The results of high power conditioning of the structure at CERN on an X-box test stand, to assess conditioning times, accelerating field and measure breakdown rates, will also be presented. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK097 | |
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| THPIK098 | Bz Calculation of TPS Linac Focusing Coils and a Toolkit for Bz Optimization | 4321 |
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| A set of focusing coils is installed along TPS linac beam centerline at low energy region (< 10 MeV) in order to confine the beam radius within 5 mm. The longitudinal magnetic field calculation along the beam centerline has been carried out in this study. The estimated Bz is obtained based on Biot-Savart law calculation. Then, it is verified by field measurement using Gauss meter at specific centerline locations. Calibration process is performed by comparing the calculated and measured Bz fields at selected operation settings. The comparison result is presented in this report. The linac operation experience indicates that tuning of the coil settings is critical concerning beam property optimization. Consequently, a Bz calculation toolkit is developed to cope with the multi-knobs optimization process while tuning of numerous focusing coils installed in the system at various locations. The applications of the Bz calculation toolkit is briefly described. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK098 | |
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| THPIK101 | Quarter Wavelength Combiner for an 8.5kW Solid-State Amplifier and Conceptual Study of Hybrid Combiners | 4324 |
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| Experimental results to combine ten 900 W solid-state amplifier modules based on typical quarter wavelength 10-way combiners are described for a total of 8.5 kW RF power output at 500 MHz. The power gain and phase distribution among the ten modules are measured and calculated to sense the combination efficiency. The combination efficiency of 100 modules differing in power gain and phase distribution is theoretically analysed. Groups of 5, 10, 25, 50 and 100 units are used in 4, 3, 2, and 1-stage power combination for total 100 units and the characteristics are calculated and investigated, including bandwidth, efficiency and even redundancy under various output VSWR levels. To simplify combining complexity and to eliminate the drawbacks of single stage combiners, a multi-way 2-stage coaxial to waveguide combiner is thus proposed as an expandable power combiner. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK101 | |
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| THPIK102 | Commissioning of the SLRI Storage Ring Second RF System | 4328 |
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| The old RF cavity in the storage ring of SIAM Photon Source (SPS), the 1.2 GeV second generation synchrotron light source in Thailand, has been pushed to its maximum capability to compensate electron energy lost in the storage ring. This energy lost is the effect from two additional insertion devices, which have been installed in SPS storage ring during June to August 2013. The new RF system has been planned since 2012, but with some technical and procurement difficulty the new system was successfully commissioning and running in August 2016. The installation, acceptance testing, conditioning and commissioning results of the new RF cavity, RF high power transmitter, and the low level RF system will be presented | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK102 | |
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| THPIK103 | Six Months of Operation of the New RF Cavity System of SLRI | 4331 |
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| The new RF cavity system has been installed in the storage ring of SIAM Photon Source (SPS) since August 2016. The RF cavity was designed base on the MAX-IV laboratory capacitive loaded type cavity. The solid-state technology was implemented in the RF high power transmitter. The low-level RF system utilized the digital technology. The system has been successfully commissioned and run with a capability to compensate an energy lost from a full capacity run of insertion devices since August 2016. This paper summarizes the problems and actions of the new RF system and presents an overview of six months of operation of the new RF system in the storage ring of SPS. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK103 | |
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| THPIK104 | Transient Simulation of the ISIS Synchrotron Singlet Quadrupoles Using OPERA 3D | 4334 |
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| Type QX106 singlet magnets are AC defocusing quadrupoles used in the ISIS main synchrotron ring. They have an aperture of 202 mm and a yoke length of 303 mm, so the end effects are significant. The iron poles and the yoke are asymmetric and the coils are driven by a 50Hz, 400 A AC current, biased with a DC current of 665 A. Therefore the yoke has to be laminated, and the laminations are slitted up to a depth of 90 mm on each side to further reduce the eddy current losses. Two 3D models (DC and transient) have been developed using OPERA 3D for different purposes. Both models require the use of an anisotropic BH curve for the yoke, and the transient model also requires an anisotropic conductivity and a prismatic/hexahedral mesh to overcome the limitations of the linear tetrahedral edge elements in OPERA's vector potential formulation. The quadrupole field quality was originally measured in 1982 with a DC excitation at the biased peak current (1065 A) and those measurements are now compared to both models. The iron losses due to the eddy currents are also presented and compared to the original specifications defined in 1980, as well as an estimation of the eddy currents in the coils. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK104 | |
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| THPIK105 | The ZEPTO Dipole: Zero Power Tuneable Optics for CLIC | 4338 |
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| Permanent magnet (PM) based systems create a significantly reduced power consumption compared to conventional room temperature electromagnets. STFC and CERN are investigating the feasibility of using tuneable PM systems to reduce high electricity and water-cooling costs; plus the associated large scale infrastructure burden in the proposed CLIC accelerator. This collaboration has previously resulted in the development of two tuneable PM Quadrupole systems. We present here a continuation of this work in the development of a pure PM C-Dipole with a tuning range of over 50%. A prototype has been simulated and constructed using a single 50x40x20 cm block of NdFeB which slides horizontally to provide tuning. We outline the design, construction and measurement of a prototype dipole and discuss its suitability as a replacement for electromagnetic systems. Issues including field homogeneity over a large tuning range and the management of high magnetic forces are addressed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK105 | |
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| THPIK106 | Low Power RF Characterisation of the 400 Hz Photoinjector for CLARA | 4342 |
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| The CLARA High Repetition Rate Photoinjector comprises an S-band dual feed cavity and will operate at a repetition rate of up to 400 Hz and is capable of reaching an electric field strength on the cathode of 120 MV/m. The cavity was brazed after tuning and arrived at Daresbury Laboratory in February 2016. Extensive low power RF testing has been performed including measurements of the quality factors and coupling, pass-band mode frequencies, on axis field and RF repeatability of replacement of cathode plug. The dual feed coupler has been tuned and a Magic Tee type splitter installed. The photoinjector is now installed on the VELA beam line for commissioning and characterisation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK106 | |
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| THPIK107 | Design and Characterisation of the Focusing Solenoidal System for the CLARA High Repetition Rate Electron Source | 4346 |
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| One of the critical components of electron injectors based on RF photoelectron sources is the focusing system. The system typically consists of a Main Focusing Solenoid and a Bucking Coil. Combination of these two solenoids should provide proper focusing of the beam at the exit of the RF cavity and zero longitudinal magnetic field in the photocathode plane to minimise the beam emittance. Imperfection of the solenoid design, manufacturing and alignment frequently leads to asymmetry of the focusing field which has to be compensated with additional coils. In order to eliminate mechanical and magnetic misalignment the CLARA photoinjector solenoids are mounted on one integrated bench and before installation into the beamline have been aligned in the magnet laboratory with simultaneous measurement of the magnetic field. In order to define multipole field components, dedicated measurements of the transverse magnetic field have been done. The amplitudes of the multipoles have been obtained from analysis of the transverse field map. We present here the results of field characterisation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK107 | |
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| THPIK108 | Bead Pull Measurements of the FETS RFQ at RAL | 4349 |
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| A Radio Frequency Quadrupole (RFQ) is a part of the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL), Didcot, UK. The aim of the FETS project is to produce a 60 mA H− beam at 3 MeV. The RFQ is a four-vane type with 4 modules, each of 1 m length, and is designed to accelerate the beam from 65 keV to 3 MeV at 324 MHz. A bead pull system has been designed to measure the field along the RFQ. This will be used in conjunction with 64 tuners to produce a uniform field. In order to optimise the tuning procedure, a model of the RFQ has been creat-ed in COMSOL Multiphysics. This study shows the results from the bead pull measurements and the tuning studies. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK108 | |
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| THPIK109 | The RF Distribution System for the ESS | 4352 |
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| The RF distribution system for the European Spallation Source will be one of the largest systems ever built. It will distribute the power from 146 power sources to the two types of ESS cavity at two different frequencies and will use one line per cavity for resilience. It will consist of a total of around 3.5 km of waveguide and coaxial line and over 1500 hundred bends. It is designed to transport this RF power over a distance of up to 40m per line, while minimising losses, avoiding reflections and allowing the monitoring of performance. This contribution will give an overview of the design of the system and its status. Installation is due to start in September 2017. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK109 | |
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| THPIK110 | RF Cavity Design for a Low Cost 1 MeV Proton Source | 4355 |
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| In this paper we present the design for a low-cost RF cavity capable of accelerating protons from 100 keV to 1 MeV. The system is designed to meet the specifications from the proposed Alceli LTD medical proton therapy linac, to deliver a 1 nA proton beam current with a 1 kHz repetition rate. We present a design of an RF normal conducting (NC) re-entrant Cu cavity operating at 40 MHz consisting of a coupled two cavity system, both driven by a single Marx generator. The choice of such a low operating frequency for the cavity system enables us to use a relatively low-cost cost Marx Generator as the RF source. Marx generators work in a similar fashion to a Cockcroft-Walton accelerator (without the expensive components), creating a high-voltage pulse by charging a number of capacitors relatively slowly in parallel, then rapidly discharging in series, via spark gaps. Marx generators can deliver 2.5 GW, 1 ns pulses, with rise times of 200 ps, and (relatively) low jitter. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK110 | |
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| THPIK112 | Progress With the Diamond Light Source RF Upgrade | 4358 |
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| Failure of a superconducting cavity in the Diamond storage ring can lead to extended down-time because of the time required to remove the module from the ring, the inability to access the cavity without removal from the cryostat and the long time to repair of the module. To reduce the risk to storage ring operation, normal conducting cavities are being installed to support operation of the superconducting cavities. Two cavities will be introduced in 2017 and work is progressing with RF amplifiers, transmission lines and low-level RF as well as storage ring engineering and controls. A summary of progress so far is presented and the plan for installation and further RF upgrades is outlined. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK112 | |
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| THPIK113 | Tuner of a Second Harmonic Cavity of the Fermilab Booster | 4362 |
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| Introducing a second harmonic cavity in the accelerating system of the Fermilab Booster promises significant reduction of the particle beam loss during the injection, transition, and extraction stages. To follow the changing energy of the beam during acceleration cycles, the cavity is equipped with a tuner that employs perpendicularly biased AL800 garnet material as the frequency tuning media. The required tuning range of the cavity is from 75.73 MHz at injection to 105.64 MHz at extraction. This large range necessitates the use of a relatively low bias magnetic field at injection, which could lead to high RF loss power density in the garnet, or a strong bias magnetic field at extraction, which could result in high power consumption in the tuner's bias magnet. The required 15 Hz repetition rate of the device and high sensitivity of the local RF power loss to the level of the magnetic field added to the challenges of the bias system design. In this report, the main features of a proposed prototype of the second harmonic cavity tuner are presented. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK113 | |
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| THPIK115 | Status of the Perpendicular Biased 2nd Harmonic Cavity for the Fermilab Booster | 4366 |
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Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. This is a status report on the 2nd harmonic cavity for the Fermilab Booster as part of the Proton Improvement Plan (PIP) for increasing beam transmission efficiency, and thus reducing losses. A set of tuner rings has been procured and is undergoing quality control tests. The Y567 tube for driving the cavity has been successfully tested at both injection and extraction frequencies. A cooling scheme for the tuner and cavity has been developed after a thorough thermal analysis of the system. RF windows have been procured and substantial progress has been made on the mechanical designs of the cavity and the bias solenoid. The goal is to have a prototype cavity ready for testing by the end of 2017. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK115 | |
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| THPIK116 | Static Magnetization Properties of AL800 Garnet Material | 4370 |
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| A second harmonic tunable RF cavity is being developed for the Fermilab Booster. This device, which promises reduction of the particle beam loss at the injection, transition, and extraction stages, employs perpendicularly biased garnet material for the frequency tuning. The required range of the tuning is significantly wider than in previously built and tested tunable RF devices. As a result, the magnetic field in the garnet becomes fairly close to the gyromagnetic resonance line at the lower end of the frequency range. The chosen design concept of a tuner for the cavity cannot ensure uniform magnetic field in the garnet material; thus it is important to know the static magnetic properties of the material to avoid significant increase in the local RF loss power density. This report summarizes studies performed at Fermilab to understand variations in the magnetic properties of the AL-800 garnet material used to build the tuner of the cavity. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK116 | |
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| THPIK117 | High Efficiency High Power Resonant Cavity Amplifier for Accelerator Applications | 4374 |
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Funding: Work supported by US Department of Energy under contract DE-SC0015780 Diversified Technologies, Inc. (DTI) has designed and built a unique integrated resonant-cavity combined solid-state amplifier. The design radically simplifies solid-state transmitters to create favorable and straightforward scaling to high power levels. A crucial innovation is demonstration of an inherently reliable soft-failure mode of operation; a failure in one or several of these myriad combined transistors has negligible performance impact. In addition, this design couples the transistor drains directly to the cavity without first transforming to 50 Ohms, avoiding the otherwise-necessary multitude of circulators, cables, and connectors. A conventional amplifier has a complete set of electrical and cooling connections for every stage, resulting in many hundreds of connections for a high power transmitter'in some DTI designs, there are as few as four. This construction both reduces the cost and increases the power level at which it is cost-effective to employ a solid-state transmitter. The prototype has demonstrated multiple-transistor combining from 300 MHz to 1300 MHz, at powers up to 5 kW. This prototype is scalable to several hundred kW at these frequencies. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK117 | |
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| THPIK118 | Final Assembly and Testing of MICE RF Modules at LBNL | 4377 |
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Funding: Work supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231 The international Muon Ionization Cooling Experiment aims to demonstrate the transverse cooling of a muon beam by ionization interaction with absorbers and re-acceleration in RF cavities. The final MICE cooling channel configuration has two RF modules, each housing a 201 MHz RF cavity to compensate the longitudinal energy loss in the absorbers. Two RF modules have been assembled and tested at LBNL. This paper reports the final assembly work, as well as the vacuum test and low level RF measurements. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK118 | |
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| THPIK120 | The RF and Mechanical Design of a Compact, 2.5 kW, 1.3 GHz Resonant Loop Coupler for the APEX Buncher Cavity | 4380 |
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Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231. The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory (LBNL) is an injector system designed to demonstrate the capability of a normal conducting 186 MHz RF gun operating in CW mode to deliver the brightness required by X-ray FEL applications operating at MHz repetition rate, such as LCLS-II. A 240 kV, 1.3 GHz CW buncher cavity design was developed as part of the APEX experiment. The two-cell cavity profile has been optimized to minimize the RF power requirements and to remove multipacting resonances over the full range of operation. In order to excite the cavity stably at pi-mode and remove the dipole-like coupler kick, the two cells are to be independently driven by four, 2.5 kW, coaxial resonant loop couplers with integrated ceramic windows and a matching section in the body of the coupler. The coupler's inner conductor has a single diameter change at a specified distance from the ceramic insulator in order to cancel the wave reflected from the ceramic window, thus comprising the matching section. The details of the RF analysis, mechanical design, fabrication and testing of the coupler are presented here. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK120 | |
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| THPIK121 | Eddy Current Analysis for a 1.495 GHz Injection-Locked Magnetron | 4383 |
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Funding: U.S. DOE SBIR/STTR grant DE-SC0013203 An injection-locked amplitude modulated magnetron is being developed as a reliable, efficient RF source that could replace klystrons used in particle accelerators. A trim magnetic coil is used to alter the magnetic field in conjunction with the anode voltage to maintain an SRF cavity voltage while the cavity is experiencing microphonics and changing beam loading. The microphonic noise modes have frequencies in the range 10-100 Hz. The changing magnetic field will induce transient eddy currents in the copper anode of the magnetron which will buck the field in the interaction region. This paper will describe the calculation and handling of the eddy currents in the magnetron. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK121 | |
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| THPIK122 | Methods of Phase and Power Control in Magnetron Transmitters for Superconducting Accelerators | 4386 |
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| Various methods of phase and power control in magnetron RF sources of superconducting accelerators intended for ADS-class projects were recently developed and studied with conventional 2.45 GHz, 1 kW, CW magnetrons operating in pulsed and CW regimes. Magnetron trans-mitters excited by a resonant (injection-locking) phase-modulated signal can provide phase and power control with the rates required for precise stabilization of phase and amplitude of the accelerating field in Superconducting RF (SRF) cavities of the intensity-frontier accelerators. An innovative technique that can significantly increase the magnetron transmitter efficiency at the wide-range power control required for superconducting accelerators was developed and verified with the 2.45 GHz magnetrons operating in CW and pulsed regimes. High efficiency magnetron transmitters of this type can significantly reduce the capital and operation costs of the ADS-class accelerator projects. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK122 | |
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| THPIK123 | Magnetron Design for Amplitude Modulation | 4389 |
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| The amplitude modulation (AM) of a magnetron is accomplished by varying the magnetic field which changes the current to the anode and the output power of the injection locked magnetron. The purpose of the AM is to compensate for microphonics in super conducting cavities by maintaining a constant gradient. The frequency range for the microphones is below 200 Hz. At these frequencies, eddy currents are encountered in the magnetron anode that reduce the effectiveness of the varying magnetic field on the magnetron current. A novel anode design is described which minimizes eddy currents and a method for manufacturing this novel magnetron anode is presented | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK123 | |
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| THPIK124 | Using Conductive Nanoparticles to Reduce the Surface Charging of Ceramics | 4392 |
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| Beam pipe ceramics used for various purposes suffer from the problem of surface charging in the presence of an electron beam. A novel technique has been proposed for a method for reducing the charging effects by filling nano sized pores in the ceramic with a conductive medium. Pores in ceramics can be formed in a chain with varying depths depending on sintering temperatures and methods for creating the pores. In the pre-formed condition of these novel ceramics, a nanoparticle slurry is infused by capillary action into the ceramic and fired at temperatures and atmospheres to stabilize the conductive medium inside the ceramic. The microwave characteristics of these ceramics will be investigated in a Phase I program with the design of a complete beam pipe lossy ceramic in a Phase II. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK124 | |
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| THPIK125 | Ultra High Gradient Breakdown Rates in X-Band Cryogenic Normal Conducting Rf Accelerating Cavities | 4395 |
| SUSPSIK097 | use link to see paper's listing under its alternate paper code | |
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Funding: Work Supported by DOE/SU Contract DE-AC02-76-SF00515, US NSF Award PHY-1549132, the Center for Bright Beams, and DOE SCGSR Fellowship. RF breakdown is one of the major factors limiting the operating accelerating gradient in rf particle accelerators. We conjecture that the breakdown rate is linked to the movements of crystal defects induced by periodic mechanical stress. Pulsed surface heating possibly creates a major part of this stress. By decreasing crystal mobility and increasing yield strength we hope to reduce the breakdown rate for the same accelerating gradient. We can achieve these properties by cooling a copper accelerating cavity to cryogenic temperatures. We tested an 11.4 GHz cryogenic copper accelerating cavity at high power and observed that the rf and dark current signals are consistent with Q0 changing during rf pulses. To take this change in Q0 into account, we created a non-linear circuit model in which the Q0 is allowed to vary inside the pulse. We used this model to process the data obtained from the high power test of the cryogenic accelerating structure. We present the results of measurements with low rf breakdown rates for surface electric fields near 500 MV/m for a shaped rf pulse with 150 ns of flat gradient. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK125 | |
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| THPIK126 | Design of a Field-Emission X-Band Gun Driven by Solid-State RF Source | 4399 |
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| We present the design of a field-emission X-band gun designed to be powered using a solid-state RF source. The source of the electron beam is a field emission nano-tip array. The RF gun is intended to be a beam source for 1 MeV solid-state driven linac for deployment on a satellite to map magnetic fields in the magnetosphere. The gun has to satisfy strict requirements on both average and peak power consumption, as well as rapid turn on time. In order to achieve low power consumption, the RF gun operates at relatively low accelerating gradient of 2 MeV/m. The beam exit energy is ~20 keV for an RF power 1.5 kW. Each cell of the RF gun is separately powered by commercially available, GaN high electron mobility transistors. In proof of principle experiments we successfully powered a 9.3 GHz accelerating cavity with a 100 W transistor and a 1% duty cycle. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK126 | |
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| THPIK128 | Switching Magnet for Heavy-Ion Beam Separation | 4403 |
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Funding: This work was supported by the United States Department of Energy SBIR Grant No. DE-SC0015124. We present a design for a complete switching magnet system capable of deflecting 8-25 MeV/u heavy-ion beams by 10 degrees. The system can produce flat-top pulses from 1 to 30 ms with rise and fall times of less than 0.5 ms at a duty cycle of 3-91% into a heavily inductive load. As determined by physics needs, the operational parameters of this magnet place it between fast rising kicker magnets with short duration and slow rising (or DC) resistive magnets which are optimized for efficiency and current-based power loss. This magnet must operate efficiently with over 91% duty factor and have a modestly fast rise time. The resulting design uses a resistive magnet scheme, to optimize the current-based losses, that is pulsed using a new circuit to control the applied voltage. The magnet has a laminated, iron dominated, H-shaped core. Directly-cooled copper pancake coils energize the magnet. The modulator employs a novel, proprietary, over-voltage topology to overcome the inherent inductance and achieve the fast rise and fall times, switching to a precision DC supply to efficiently maintain the flattop without requiring voltage in excess of ±3 kV. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK128 | |
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| THPIK129 | Non-Linear Inserts for the IOTA Ring | 4407 |
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Funding: Work supported by DOE under contract DE-SC0009531. We present here the complete non-linear insert for the IOTA ring at Fermilab. In particular, we will show the results for the magnetic measurements and a discussion of leak correction in the unusually shaped vacuum chamber. A test assembly of the insert has been successfully completed and the insert functions mechanically as designed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK129 | |
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