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| TUPMA036 | Comparative Studies of Electron Sources for a Free Electron Laser at PSI | emittance, electron, gun, space-charge | 157 | ||
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Within the low emittance gun project LEG, the Paul Scherrer is currently conducting research into the development of a high brightness electron source suitable for free electron laser. The gun, planned to generate up to 5.5 Amperes of beam current, consists of a pulsed DC diode followed by a 1 1/2 cell RF gun. Using specialized codes, the performance of field emitter arrays is evaluated assuming realistic geometries. As alternatives, we examine the performance of using individual macroscopic field emission tips or conventional photo emission using copper cathodes. For these, optimized cathode geometries are presented and the performance is compared to that of field emitter arrays.
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| TUPMA042 | Beam Parameters of the SCSS Prototype Accelerator Designed by PARMELA and Comparison with Measured Values | electron, emittance, gun, simulation | 169 | ||
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The 250 MeV prototype facility of the SCSS X-FEL project was constructed in the Octorber 2005 and the machine commissioning was started in May 2006. One month later, we have succeeded in confirming the amplification of the synchrotron radiation. The electron beam parameters, such as peak current and emittance, have been designed and estimated using PARMELA. In contrast to other X-FEL projects, the SCSS injector uses a thermionic pulsed electron gun [1]. Compared with RF photocathode guns, the thermionic gun is stable and easy to handle. Its peak current, however, is smaller, and the compression of the electron bunch is necessary at early stage of the low beam energy injector. In this report, we compare the simulation and measured values, such as a bunch length and projected emittance, on the SCSS prototype accelerator. The measured beam parameters, after the bunch compression procedure and emittance degradation due to space charge, show fairly good agreement with the simulation.
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[1] K. Togawa, et al., “Emittance Measurement on the CeB6 Electron Gun for the SPring-8 Compact SASE Source”, Proceedings of the 2004 FEL Conference, (2004)351-354, URL: http://www. JACoW.org. |
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| TUPMA047 | Development of a Photocathode DC Gun at JAEA-ERL | gun, electron, emittance, laser | 175 | ||
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An electron gun producing an e-beam with high-brightness and high average-current is a key component to realize a next-generation X-ray light source based on energy-recovery linac (ERL). In JAEA, we are developing a photocathode DC gun for a future ERL light source. The DC gun is operated at 250 kV and 50 mA at maximum, and equipped with a load-lock chamber for cathode preparation. In order to keep small emittance at high current operation, we adopt superlattice semiconductor as a photocathode. In this paper, we present the status of the gun development and future plans towards the ERL test facility to construct in collaboration with KEK.
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| TUPMA049 | Development of an Injector to Generate a Very Short Bunch for a Super Coherent Terahertz Light Source Project | gun, simulation, sextupole, emittance | 178 | ||
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A project to develop a coherent Terahertz (THz) light source is in progress at Laboratory of Nuclear Science, Tohoku University. The coherent synchrotron light in the THz region is emitted from electron bunches with a very short bunch less than 100 fs (rms) generated by a thermionic RF gun and a sophisticated bunch compressor. As an injector of this ring, we have developed an independently tunable cells (ITC) RF gun and a magnetic bunch compressor. The longitudinal phase space extracted from the ITC-RF gun can be manipulated by feeding RF microwave to cells independently. To generate a short bunch with a significant bunch charge, a magnetic compressor is used downstream from the gun. Two kinds of bunch compressors have been studied. From simulation of an injector, we have got a very short bunch length about 42 fs (rms). A prototype of the gun has been manufactured. Results of low power tests of the gun will be presented.
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| TUPMA052 | Study on Compact DC Electron Gun using Single Crystal Cathode of LaB6 | gun, emittance, electron, simulation | 181 | ||
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A novel, compact DC gun has been designed and is currently on a test bed at LNS. Applying 50 kV high voltage for the gun, it is expected to supply a high brightness beam of which the beam current of 300 mA and the variable pulse duration from 1 to 5 ?sec. In addition, a floating bias voltage can be applied between the cathode and the wehnelt to manipulate electric field near cathode surface. In order to produce lower emittance beam, the thermionic cathode should have very much higher current density and the size of that should be very small. Consequently we have chosen single crystal LaB6 as the thermionic cathode, which can provide higher current density with good homogeneity electron emission. The design parameters and initial operating experience of the DC gun are discussed. This DC gun will be used for free electron lasers such as backward-wave oscillator, advanced accelerator researches and other experiments. Results of numerical calculations show good distribution of macroparticles in the phase space, which results from optimization of the bias voltage. A normalized rms emittance at the exit of the gun is expected to be less than 1 ? mm mrad.
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| TUPMA083 | High Quantum Efficiency Photocathode for RF Guns | gun, laser, space-charge, electron | 223 | ||
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High Quantum Efficiency Photocathodes are nowadays routinely used as electron sources for laser driven RF guns. In this paper, we review the production, characterization and operation performances of the Cs2Te photocathodes prepared at INFN Milano – LASA and operated at DESY for the FLASH and the PITZ photoinjectors.
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| WEPMA011 | Design and Operating Experience of Triode Electron Guns for Industrial Electron Accelerators | gun, electron, linac, emittance | 348 | ||
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The Accelerator and Pulse Power Division of BARC is presently constructing three industrial electron accelerators for radiation applications. a) a 500 keV, 10 KW Cockcroft-Walton accelerator b) a 10 MeV ,10 KW RF electron linac and c) a 3 MeV, 30 KW DC machine. While the DC accelerators require an almost parallel beam with less than 0.5 degree divergence, the RF linac gun requires a 50 keV , 2 ampere pulsed beam of low emittance Using relativistic electron optics, including space charge effects, very simple triode gun designs with flat cathode, grid and anode apertures which fulfill these requirements and are easy to fabricate experimentally are described. Our operating experience with these guns will also be described.
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| WEPMA022 | Electron Guns and Beamlines in the View of Emittance Compensation | gun, emittance, electron, space-charge | 360 | ||
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Space charge effect is ever of fundamental importance for low-energy parts of accelerators. Criteria of the significance of space charge effect are derived in the presentation. Simple and robust estimations of the emittance degradation in various space charge affected beamlines and electron guns were obtained analytically and numerically. Nonuniform longitudinal and transverse distribution of current, accelerating and bunching were taken into account. The parameters of optimal beamlines for space charge affected beams were estimated.
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| WEPMA139 | Development of High-power Microwave Devices in Toshiba | klystron, electron, vacuum, linac | 511 | ||
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Vacuum microwave devices continue to be essential for high-power RF accelerator systems and plasma heating or current drive systems for fusion experimental devices. Klystrons are suitable for use in amplification at the frequency ranges from 300 MHz to X band, while gyrotrons are mainly utilized in the millimeter wave range. Input couplers also play an important role in the building of acceleration cavity systems. TETD (Toshiba Electron Tubes & Devices Co., LTD.) has been developing these vacuum microwave devices in collaboration with some Japanese research institutes. Two kinds of long-pulse klystron for the J-PARC project were developed in collaboration with KEK and JAEA, which each have their operation frequencies, 324 MHz and 972 MHz. Both tubes output 3 MW with the pulse duration of 0.62 ms at the repetition frequency of 50 pps. They have a triode-type electron gun and same beam parameters and operate with an anode-modulating mode to reduce the cost of the power supply system.
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| WEPMA140 | Development of C-band Multi Beam Sub-booster Klystron | klystron, electron, simulation, gun | 514 | ||
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A C-band small multi beam klystron (MBK) has been under development. It is designed for the sub-booster klystron which is required to drive multiple 50 MW C-band klystrons for the SuperKEKB injector upgrade plan. The designed output power is over 100 kW in case of the applied voltage of 25 kV which is suitable for the existing pulse modulator for the S-band sub-booster klystron. At this operating condition, the designed micro-perveances of the total and the each beamlet are 2.0 and 0.25 respectively. The design overview will be presented.
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| WEPMA144 | High Power Microwave Generation From Coaxial Virtual Cathode Oscillator | electron, impedance, plasma, space-charge | 523 | ||
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A coaxial virtual cathode oscillator (VIRCATOR) has been designed to generate Relativistic Electron Beams and High Power Microwaves. Coaxial virtual cathode oscillators are known for better efficiency compared to the axial virtual cathode oscillators. This Coaxial VIRCATOR has been designed for the KALI-5000 (1MeV, 60kA, 100 ns) pulse power system. Provision for a large anode cathode gap has been kept to avoid the prepulse effect during the electron beam generation from the KALI-5000 system. Experimental studies are carried out to generate and characterize Relativistic Electron Beams and High Power Microwaves. Relativistic Electron Beams are generated by the Coaxial Explosively emitted graphite cathodes. Electron beam voltage has been measured by a copper sulphate voltage divider and beam current by a B-dot probe. High Power Microwaves are detected by the glow of neon lamps placed closed to the output window.
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| WEPMA145 | Development of A 35 Kw Power Amplifier At 350 Mhz For RFQ Accelerator Based Neutron Generator | power-supply, controls, rfq, simulation | 526 | ||
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A Radio Frequency Quadrupole (RFQ) based 14 MeV Neutron generator is being developed at BARC, as a part of its ADSS program. It is estimated that RF power of about 70 KW is required in RFQ to accelerate 1mA deuterium beam up to 400 KeV. Hence two RF systems, feeding power of about 35 KW at each of the two ports of the accelerator, are being developed. Each RF system employs a 100 W solid state driver, 1500 W intermediate power amplifier (IPA) using EIMAC 8938, and a high power amplifier (HPA) using TH571B. Solid state driver has been tested to 100 W. The IPA has been tested to 100 W in grounded grid configuration and with half wavelength strip line output circuit. The HPA cavity with tube is installed and being analyzed at low power. The 6 1/8 inch, 50 Ω coaxial transmission line has been simulated in Microwave Studio for analyzing RF parameters. The anode power supply (12KV/10 Amp) of HPA has been tested and installed. A spark gap based crowbar circuit for anode is under construction. For HPA the thyristor based safeguard circuit for screen grid, a ramping filament control circuit (0 to 8 Volts in 5 minutes) and an overall control-interlock system has also been developed.
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| THPMA039 | 300 kV/ 6 kW Power Supply System for Self-shielded Low Energy DC Accelerator at RRCAT Indore | controls, power-supply, electron, damping | 679 | ||
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A compact, low energy, self-shielded dc accelerator for industrial applications requiring beam energy in the range of 100 to 300 keV is under development at RRCAT, Indore. The power supply and control system for this accelerator is discussed here in this paper. The high voltage source is a series fed cascade generator driven by a 30 kHz sine wave inverter. Two asymmetrical cascade generators are run in parallel to enhance the current capacity of the generator. A 15-0-15 kV, 30 kHz ferrite core transformer interfaces the cascade generators with IGBT based H-bridge inverter. A buck chopper controls the dc bus voltage of the inverter so as to control the terminal voltage of the high voltage generator. A low power high frequency inverter generates the filament power supply floating at terminal voltage of the accelerator through a capacitive isolation column. Control of the filament power supply is achieved by sensing the accelerator beam current and controlling the low power inverter in a closed loop. A PC based control system designed with Lab-view 7.0 software and ADUC812 Micro-converter cards monitors and displays the various parameters of the power supply and accelerator.
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| THPMA076 | Development of the Klystron Modulator using a High-voltage Inverter Power Supply | klystron, power-supply, controls, linac | 743 | ||
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The existing klystron modulator in the Linac use a 60 Hz high voltage power supply and adopt traditional L-C resonant charging scheme with De-Qing circuit. The stability of the output high voltage is not satisfactory especially when the AC line voltage fluctuations. If an inverter power supply is used as a HV generator, it will just meet the demands A high frequency inverter switching makes the overall system size small. The command-charging feature can guarantee the high reliability of switching function. In order to increase the stability, operating reliability and comply with the PLC (programming logic controller) and touch screen control system of PLS, an upgrading works is now in progress. This paper will discuss some inverter power supply design considerations and show the test results.
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| THPMA102 | The Proton and Ion Linear Accelerator ILU-9 | ion, acceleration, proton, feedback | 788 | ||
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The pulse RF ion linear accelerator of ILU-9-type is described. The accelerator is intended to use for various radiation-technological processes and investigations. The main parameters of the accelerator are: energy of accelerated protons 2.9 or 5 (with additional accelerating section) MeV, energy of accelerated deutons 5.8 or 10 MeV, average current of accelerated ions up to 100 μA. Pulse operating mode as following: pulse duration-500 s, maximum pulse repetition- 50 Hz. The frequency of accelerator resonator is 43 MHz. Also data of carbon ions C12+4 acceleration probability are given.
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| THPMA126 | Beam Optics Design for DC High-voltage Accelerator of MW Level | gun, electron, extraction, optics | 818 | ||
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Here, we report on the working group ''beam optics design'' of MW levels dc high-voltage accelerator, that will be used in radiation technologies in large-scale industrial production (flue gas treatment, metallurgy; waste water treatment, etc.). This workshop also had working groups on ''Electron Guns Designs and Beam control device'', ''MW level high-voltage power supply designs and fabrication'', and ''Beam scanning and extraction devices designs and fabrication''. Comparing with existent high-voltage accelerators, our facility have higher average power of >500mA dc, which resulting in some technological challenges on beam production, power supply, and beam extraction. Here, we are concerned with several proposals that other laboratories have been working on. Subjects of concern are optics, accelerator design and modeling, stability requirements that connects the conventional DC high-voltage accelerators for round-the-clock operation. We describe the design, the projected performance and the status of our facility.
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WANG Han-bin*, XU Zhou, JIN Xiao, LI Ming, LIU Xi-san |
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