| Paper | Title | Page |
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| TUPD002 | Development of an Eddy Current Septum for LINAC4 | 1434 |
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| The bump for the new PS Booster injection from the future Linac4 will be made up of a set of four pulsed dipole magnets; the first of these (BS1) must act as a septum with a thin element dividing the high-field region of the circulating beam from the field-free region through which the injected H- beam must pass. BS1 will provide a deflection of 66 mrad at 160 MeV; this will be achieved with a peak field of 630 mT and a length of 200 mm. The field must rise and fall in 40 microseconds and have a flattop of up to 120 microseconds. The ripple of the flattop should be below ±1%. This paper discusses the design of an eddy current septum for BS1. | ||
| TUPD003 | Upgrading the Fast Extraction Kicker System in SPS LSS6 | 1437 |
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| A fast extraction system, located in the LSS6 region of the CERN SPS accelerator, transfers 450 GeV/c protons, as well as ions, via the transfer line TI 2 towards the LHC. The system includes three travelling wave kicker magnets, all powered in series, energised by a single Pulse Forming Network (PFN) and terminated by a short circuit. The specification for the system requires a kick flattop of 7800 ns duration with a ripple of not more than ±0.5%. Recent measurements with beam show that the ±0.5% kick specification is achieved over the initial 7100 ns of the kick flattop; however the ripple over 7800 ns is ±0.7%. Electrical measurements have been carried out on each of the three magnets: these have been compared with the beam measurements and the contribution of each magnet to the detailed shape of the flattop kick has been determined. This paper reports the results of measurements and describes the plans to upgrade the system to fully meet the kick specification. | ||
| TUPD004 | 10Hz Pulsed Power Converters for the ISIS Second Target Station(TS-2) | 1440 |
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| The Extracted Proton Beamline to the ISIS second target station has two 10Hz pulsed magnet systems which extract the proton beam from the existing 50Hz beamline. Kicker 1 magnet system deflects the beam 12.1mrad and kicker 2 magnet system deflects the beam 95mrad. Both magnets are identical, however each pulsed power converter is considerably different. This paper describes the design requirements, topology, installation, testing and successful operation of both pulsed power converters. | ||
| TUPD006 | The Injection and Extraction Kicker Circuits for the Elettra Booster | 1443 |
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| The design, realization and performance of the power circuits for the Booster injection and extraction Kicker magnets are presented. Both circuits have been designed and developed with the goal to achieve reliable working conditions, simple maintenance and fast recovery time in case of failures. The circuits are designed around the same switching unit already adopted in the Kicker system of the Storage Ring injection; this allows storing common spare parts for both circuits and for the Storage Ring Kicker system as well. Beside the analytical analysis, a parametric study of the circuit, with the Microsim PSPICE software package, allowed to optimize the performance of the circuit regarding the parameters which were considered critical for the Booster injection and extraction processes, i. e. the current pulse rise time and fall time. | ||
| TUPD007 | The Design and Fabrication of the Kicker Power Supply for TPS Project | 1446 |
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| The preliminary test results of the kicker power supply for TPS (Taiwan Photon Source) project will be presented in this report. The achieved capability of this test unit demonstrates that it fulfills the design requirement of providing half-sine pulsed current of 2.5 kA (peak), 5.2 s (base-width), with jitter < 1 ns (peak-to-peak). Both units of using thyratron and IGBT switches are built with the same requirements. The technical considerations of both units for this particular application will be discussed. | ||
| TUPD008 | Marx Bank Technology for Accelerators and Colliders | 1449 |
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| Diversified Technologies, Inc. (DTI) has developed high power, solid-state Marx Bank designs for a range of accelerator and collider designs. We estimate the Marx topology can deliver equivalent performance to conventional designs, while reducing acquisition costs by 25-50%. In this paper DTI will describe the application of Marx based technology to two different designs: a long-pulse ILC focused design (140 kV, 160 A, 1.5 ms), and a short-pulse design (500 kV, 265 A, 3 us). These designs span the known requirements for future accelerator modulators. For the ILC design, the primary challenge is minimizing the overall size and cost of the storage capacitors in the modulator. For the short-pulse design, the primary challenge is high speed operation, to limit the energy lost in the pulse rise-time while providing a very tight (± 3%) voltage flattop. Each design demands unique choices in components and controls, including the use of electrolytic capacitors in the ILC Marx design. This paper will review recent progress in the development and testing of both of these prototype Marx designs, being built under two separate DOE Phase II SBIR grants. | ||
| TUPD010 | High-power Switch with SI-thyristor for the Power Supply of Very High Repletion Rate Pulsed Quadrupole Magnet | 1452 |
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| A solid-state switch with SI-thyristors is implemented as the high power switch for the pulsed quadrupole magnet power supply. Its repletion rate is 100 kHz with the half sign 1 microsecond pulse. The switch has been successfully operated. | ||
| TUPD011 | The Pulsed Quadrupole Magnet for KEKB Low Energy Ring | 1455 |
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| In the KEKB low energy ring, because of photoelectron clouds, the betatron tune changes along the position in the train. The produced photoelectron gives focusing force to the beam. It is remarkable especially in the vertical tune. Since we have a 500 nanoseconds beam abort gap, the photoelectron focusing force is weaker at the head of train. It means the vertical tune is lower at the head of the train. In order to cancel this tune shift, the pulsed quadrupole magnet was installed. The pulsed quadrupole magnet system and its performance are described. | ||
| TUPD014 | Detailed Design, Manufacturing and Testing of a Strip-line Extraction Kicker for CTF3 Combiner Ring | 1458 |
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| The first calculations to design the CTF3 Combiner Ring extraction kicker are reported elsewhere. The last computing step before fabrication is the wakefield analysis, to determine if the bunch disturbance is acceptable. Two different codes have been used for cross-checking: CST Particle Studio and GDFidl. The computation is challenging because of the long structure (2.4 m) with a short bunch (3 mm). Besides, both transitions are not equal, because of different straight sections of the input and output beam pipe, and then the solution method is more complex. On the other hand, the main challenges for manufacturing are the long electrodes support via ceramic stand-offs and the flexible electrical connections to allow for electrodes thermal differential displacement. Special tooling has also been developed for assembly within the required tolerances. The device has been successfully leak tested. High frequency transmission coefficients and high voltage dielectric strength were also measured. | ||
| TUPD016 | Grounding and Induced Voltage Issues of the Injection Bump Magnet System of the 3-GeV RCS in J-PARC | 1461 |
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| The power supply of the injection shift bump magnets is required to rate a large current with high precision. The rating current is 20 kA and the pulse width is 1.3 ms. The power supply with the multiple connected two-quadrant IGBT choppers, which is controlled by the switching frequency over 48 kHz, realizes the tracking error less than 1.0 %. However, the switching noise due to the IGBT choppers caused damages to the control device and the measuring instrument. The ground cables were changed to copper sheets, so that the voltage due to the switching noise between the power supply board and the ground decreased from 800 V to 40 V. Furthermore, the output voltage of the RF shield was measured in connection with the several waveform patterns. These results showed the good agreement with the calculation and the experiment. The good performances of the shift bump magnet and power supply have been confirmed. | ||
| TUPD017 | Design of Main Ring Dipole Power Supply for HIRFL-CSR | 1464 |
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| This paper introduces the main circuit topologic, control method and double reference setting system of a dipole power supply which is the pivotal device of the HIRFL-CSR(Heavy Ion Research Facility in Lanzhou-Cooling Storage Ring). The power supply works at the pulse mode, with the peak output power of 3.15MW (3000A, 1045V). To fulfill difficult requirements especially for the tracking error, which is needed less than 300ppm, a special topologic is adopted. The power supply has two parts: SCR rectifier provides the most energy and PWM converter provides correcting current and perfect reaction for tracking current setting. Now the dipole power supply is performing well during the CSR commissioning, with the perfect tracking error, well long-time stability and low ripple current. | ||
| TUPD019 | Inter-disciplinary Mechanical and Architectural 3D CAD Design Process at the European XFEL | 1467 |
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| Realising the European-XFEL involves creating and coordinating several types of 3D design models for many different subsystems like underground buildings, utilities, accelerator systems or photon beam lines. In order to handle the huge amount of data, reduced envelope models are needed for integrating the subsystems towards the complete facility and to ensure that the different subsystems connect properly and do not intersect. Detailed component design models are required for planning approval, tendering or in-house production. A key issue was to develop an optimized design for the facilities while still being able to accommodate possible late R&D-driven design changes of subsystems. The paper describes the procedures and tools which are used for planning and designing the European-XFEL and reports benefits and experience. The procedures in use allow visualization of the facilities, negotiation of requirements and solutions between all the working groups, optimized storing of the documentation as well as running approval and change management procedures. Tools in use include a requirements database, 3D-CAD systems and an engineering data management system. | ||
| TUPD020 | Remote Alignment of Low Beta Quadrupoles with Micrometric Resolution | 1470 |
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| Considering their location in a high radiation environment and the alignment tolerances requested, the Low Beta quadrupoles of LHC will be positioned remotely (controlling 5 degrees of freedom), with a displacement resolution of few microns in horizontal and vertical. Stepping motor gearbox assemblies are plugged into the jacks which support the cryomagnets in order to move them to the desired position regarding the quality of the beam collisions in the detectors. This displacement will be monitored in real time by the sensors located on the magnets. This paper describes the positioning strategy implemented as well as the software tools used to manage it. | ||
| TUPD021 | Sliding Force Measurements on the LHC RF Contact Plug in Modules at 15 K and in UHV | 1473 |
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| Some sliding RF contacts mounted in the Plug In Modules in the LHC interconnects failed during a thermal cycle between 4.2 K and room temperature. Gold-coated copper-beryllium RF fingers buckled during the warm up of the machine, indicating that one or more parameters during operation (e.g., the friction coefficient under vacuum) might be different from what was used in the calculations. This report describes the measurement of the longitudinal forces acting on the sliding RF fingers at operating vacuum and temperatures. | ||
| TUPD022 | Electron Beam Polarimetry at the S-DALINAC | 1476 |
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| It is planned to carry out experiments at the Superconducting Darmstadt Linear Accelerator S-DALINAC with both polarized electron and photon beams at the energy of the electron beam between 10 and 130 MeV. In order to extract asymmetry from these experiments the absolute degree of the electron beam polarization needs to be known. We present the existing and planned polarimeters at the source of polarized electrons and the experimental sites, especially a 100 keV Mott polarimeter and Möller polarimeter for 15-130 MeV electrons. | ||
| TUPD024 | Results of ELBE Window and Coupler Tests with a Resonant Ring | 1479 |
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| A new test bench based on a resonant ring has been built at ELBE to run window as well as coupler tests. The resonant ring is driven by a 10 kW klystron and allows tests with RF power up to 100 kW in CW mode and about 200 kW in pulsed mode. Coupler tests are done with liquid Nitrogen cooling under almost real conditions. The results of warm window and coupler tests in pulsed and CW mode are presented. Also details about the ring and a special designed coupler tip to rectangular waveguide transition are given. | ||
| TUPD027 | Commissioning of the Offline-teststand for the S-DALINAC Polarized Injector SPIN | 1482 |
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| At the superconducting Darmstadt linear electron accelerator S-DALINAC a new injector for polarized electrons is under development. For this purpose an off-line test stand has been constructed. It consists of the source of polarized electrons and a test beamline including a Wien filter for spin manipulation, a Mott polarimeter for polarization measurement and various beam steering and diagnostic elements. The polarized electron beam is produced by photoemission from a strained GaAs cathode. We report on the status of this project and present first results of the measurements of the beam properties. We also give an outlook on the upcoming installation of SPIN at the S-DALINAC. | ||
| TUPD028 | How to Stably Store Electron Beam in a Synchrotron Radiation Facility from the Point of View of an RF System Design | 1485 |
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| In any synchrotron radiation facilities, the users wish that electron beams are stably stored without beam abortion for as long as possible. It must be recognized that RF system is a main cause of beam abortions. In order to store beam stably, it is necessary for staffs in charge of RF system to foresee various beam instabilities and to take measures. Before discussing coupled-bunch instability problems, one should understand some trivial issues such as ion trapping and fundamental acceleration frequency modulated by high voltage ripple. The former causes transverse mode instability and the latter shakes stored electron beam longitudinally in RF cavities. In newly designed synchrotron radiation facilities, those issues mentioned above should be suppressed before beam commissioning. As for other issues relating with RF system, we would like to state the importance of a water-cooling system with stable temperature for cavities, and the electric earth problem of low level RF system and high voltage power equipment of a klystron. We describe how we have managed those issues in designing of SPring-8 RF system of the storage ring. | ||
| TUPD030 | Distributed Project Management at the European XFEL | 1488 |
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| The European XFEL project at DESY has introduced a distributed project management system (DPMS) based on Microsoft Project Enterprise to keep track of schedules, resource usage, investment planning and actual costs. The XFEL project is organized into more than 40 work packages (WP) which address the different technical subsystems, global infrastructure and general tasks. Each WP is led by a work package leader (WPL) who is responsible for the WP budget, schedule and resources. The DPMS enables WPLs to directly create and update project plans for their WP, and it automatically creates high-level aggregated views for the project management office. Along with the system introduction, processes for distributed project planning, controlling and reporting have been established. One of the key challenges which can be resolved with the DPMS is to identify and track dependencies among different WPs, and to determine and escalate the impact of changes in one WP to other WP schedules. The DPMS is in operation since early 2007. The paper gives an overview of the system and the established project management processes and reports experience. | ||
| TUPD031 | Crystals Application in the TOTEM Experiment to Increase the Acceptance of a Roman Pot | 1491 |
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| Bent crystal may enhance the physics reach of a near-beam physics detector in the CERN-LHC, by increasing the acceptance of scattered protons in low transverse momentum reactions. As an example we present simulations demonstrating the increase of the Roman Pot acceptance in the TOTME apparatus. Starting from the MadX v6.5 nominal optic, a crystal is placed at different longitudinal and transversal positions: for each scheme a gaussian beam of protons with different kinematic variables is created and tracked along the optical line with crystal. The number of protons with transversal coordinates greater than 10σ+0.5mm, that is inside the Roman Pot, is compared with the total number of protons. The possible gain in acceptance is around 15-20%. | ||
| TUPD032 | RFQ Vacuum Brazing at CERN | 1494 |
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| The aim of this paper is to describe the vacuum brazing procedure used at CERN for the brazing of Radio Frequency Quadrupole (RFQ). The RFQ is made of high precision machined OFE copper pieces assembled together. Vacuum brazing is one of the most promising techniques used to join the individual components leading to vacuum tightness and high precision alignment. The RFQ's brazed at CERN are made of four 100 or 120 cm long vanes (two majors and two minor vanes). Our brazing procedure consists of two steps. The first step involves the brazing of the four vanes in a horizontal position. The second step consists of brazing the vacuum stainless steel flanges to the copper structure in a vertical position. The paper describes the problems encountered with the alignment and the vacuum tightness. The difficulties related to the stress relaxation of the machined copper pieces during the brazing heat treatment are discussed. In addition, the solutions developed to improve the alignment of the brazed RFQ's are also presented. | ||
| TUPD033 | Fabrication of Crystals for Channelling of Particles in Accelerators | 1497 |
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| Channelling in bent crystals is used for beam extraction, focusing, collimation in accelerators machines, studies related to emission of coherent electromagnetic radiation and other topics. Distinctive features of performance increase is the availability of new techniques to manufacture the crystals within which channeling takes place. We propose a method to fabricate crystals through micromachining techniques, i.e., photolithography and anisotropic chemical etching. Patterning of a Si wafer with silicon nitride allows selective erosion of uncovered areas along specific atomic planes, resulting in a technique to dice Si wafers to the needed dimensions solely through chemical methods. Thus, it results in no damage to the crystal quality due to the dicing process. As was demonstrated by electron microscopy investigation, the crystal exhibits ultra flat lateral surfaces and simultaneously no amorphous layer at the entry face of the crystal with respect to the beam. The crystals were positively tested at the external line H8 of the SPS with 400 GeV protons for investigation on axial channeling and on single and multiple volume reflection experiments by the H8-RD22 collaboration. | ||
| TUPD034 | Review of the Mechanical Engineering Challenges Associated with the SNS Power Ramp Up | 1500 |
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| Since commissioning of the SNS in April 2006 the beam power has been steadily increasing towards the design intensity of 1.4 MW. Several areas of the accelerator have been shown to require modifications, upgrades or new designs of mechanical equipment to support the power ramp schedule. This paper presents mechanical engineering design work implemented since initial commissioning along with a review of current projects and discussion of mechanical engineering issues being addressed that are a direct result of design decisions made early in the project. | ||
| TUPD035 | Modeling of the RF-shield Sliding Contact Fingers for the LHC Cryogenic Beam Vacuum Interconnects Using Implicit and Explicit Finite Element Formulations | 1503 |
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| The short interconnect length between the LHC superconducting magnets required the development of an optimised RF shielded bellows module, with a low impedance combined with compensation for large thermal displacements and alignment lateral offsets. Each bellows is shielded by slender copper-beryllium fingers working as pre-loaded beams in order to provide a constant force at the sliding contact. Unless the sliding friction and some geometrical parameters of the fingers are kept within a limited range, a large irreversible lateral deflection towards the vacuum chamber axis may occur and eventually block the beam aperture. The finite element analysis presented here simulates this failure mechanism providing a complete understanding of the finger behavior as well as the influence of the various design parameters. An implicit non-linear two-dimensional model integrating friction on the sliding contacts, geometrical non-linearity and plasticity was implemented in a first stage. The design was then verified through the whole working range using an explicit formulation, which overcame the instabilities resulting from the sudden release of internal energy stored in the finger. | ||
| TUPD036 | G4Beamline Simulations for Detector Development | 1506 |
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| In current research programs to develop radiation detection instruments, simplifying assumptions are frequently made in estimating the resolutions and efficiencies attainable by neutron and gamma-ray instruments. Monte Carlo programs (such as Geant4) are capable of realistically modeling such problems, but the technical details of setting up, running, and interpreting the required simulations are beyond the ability of all but the most expert researchers. G4beamline, a program that is an interface to the Geant4 toolkit for the simulation of accelerator beam lines, is being extended to model detectors and related systems needed for applications related to nuclear nonproliferation and other users. The program is flexible, extremely user friendly, and requires no programming by users. Simulations of simple or complex detectors can be setup quickly and are accurately simulated using the power and accuracy of Geant4 for the transport of particles, including scattering, attenuation, interactions, and decays. | ||
| TUPD037 | Design and Development of Intercepting Devices at the Spallation Neutron Source | 1508 |
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| Beam measurements in the LINAC and transport lines of the Spallation Neutron Source at Oak Ridge National Laboratory utilize a variety of intercepting instruments such as in-line emittance systems, wire scanners, scrapers and scintillation view screens. All of these devices require linear actuators with vacuum feedthroughs. The majority of the actuators acquired during the construction phase of the SNS were of commercial origin and have proven unable to meet long-term physics and engineering requirements. The predominant difficulties with these devices were lack of precision, reliability and longevity. Three new families of linear actuators have been developed at the SNS to address these deficiencies. The approach used in their development, has been to utilize a combination of commercially available linear motion components in custom built chassis to address the needs of a given set of applications. This approach has yielded devices that have met or exceeded expectations for accuracy, precision, radiation resistance, longevity and economy. Aspects of the underlying design of these actuators and their implementation will be presented at this conference. | ||
| TUPD038 | Beam Test of a Movable Collimator (Mask) with Low Beam Impedance | 1511 |
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A movable collimator with low beam impedance for future high-intensity machines has been investigated in KEK*. The metal head of the collimator is supported by a dielectric material in order to reduce the interference with beams. The first test model was installed into the KEK B-factory (KEKB) positron ring last year. The head and the support was alumina ceramic, but only the head was coated by copper to realize a conductive layer. The support, however, was finally melted during the beam operation due to the overheating by intense electromagnetic fields induced by bunches. Based on the experience, the design was revised and the second test model was manufactured, where the head and the support were made of graphite and artificial diamond, respectively. Graphite is a conductive material with high thermal strength, and diamond, on the other hand, is a dielectric material with high thermal conductivity as well as the strength. The second test model is installed in the spring of this year, and tested again with beams during the beam operation to prove the principle. The results of the beam tests will be presented here.
* Y. Suetsugu, K. Shibata, A. Morishige, Y. Suzuki, M. Tsuchiya, “Design Study of a Movable Mask with Low Bema Impedance”, PRST-AB, 9, 2006, 103501. |
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| TUPD039 | Load Curves Distortion Induced by Fringe Field Effects in the Ion Nanoprobe | 1514 |
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| Nanoprobes are known to be high precision systems, which require preliminary modeling for thorough analysis of optimal working modes. One of most crucial characteristics of the special class of such beam lines is the so-called load curves (or surfaces). This paper investigates one of the types of intrinsic effects, i.e. fringe fields and their influence on load curves and surfaces, which make it possible to construct the purposeful search of optimal working regimes for nanoprobes. A number of different models for fringe field presentation are discussed in the paper. Analytical and numerical methods and tools are used for analysis and selection of optimal parameters for fringe field models. | ||
| TUPD040 | Design, Manufacturing and Tests of a Micrometer Precision Mover for CTF3 Quadrupoles | 1517 |
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| A new remotely controlled moving table has been designed for the quadrupoles of the CTF3 Test Beam Line, as part of the beam based alignment system. This device must provide both vertical and horizontal (transverse to the beam) movements. The specifications request a reproducibility of ± 5 micron, with a resolution of 1 micron and a stroke of ± 4 mm. Due to the weight of the magnet, about 50 kg, and the space restrictions, a solution based on small stepping motors with integrated linear spindles has been chosen. The motor responsible of the vertical movement rests on a wedge, with a double purpose: to make the design more compact, and to increase the lifting force for a given motor size. Mechanical switches are used as end-of-movement sensors and home position detectors. The performed tests to check the mover prototype performance are also reported in this paper. Next step will be to launch series production, which will consist of 16 units. | ||
| TUPD041 | The Design of a 5 MeV Accelerator Based on Multipactor Electron Gun | 1520 |
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| The Multipactor Electron Gun (MPG) based on the multipactor effect can produce short duration, high current and self-bunching electron beams. This paper presents our work on the design of an S-band accelerator based on MPG and the result of preliminary experiment. The mechanical structure was designed with ability of replacing secondary electron emitters. Pd-Ba alloy and Pt were used as the secondary electron emitters of the MPG. The distance between electrodes and the resonant frequency of the MPG can be adjusted separately by step motors. The parameter of the accelerator tube was optimized using numerical simulation with the design outlet energy of the electron is 5MeV and an average current of 100mA. |