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| TUPMA035 | SCSS Prototype Accelerator Timing System | electron, controls, acceleration, klystron | 154 | ||
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SPring-8 Compact SASE-FEL Source (SCSS) project is in progress. To verify its feasibility, the 250MeV SCSS prototype accelerator (SPA) was constructed and beam commissioning started in October 2005. We observed first lazing of 49nm wave length in June 2006. In this paper, we describe the timing system of SPA. The target time jitter was selected under 1ps. To achieve this, A master trigger generator unit (MTU), a master trigger distribution unit, a 5712MHz synchronous trigger delay unit (TDU) and a level converter unit were newly developed. The MTU generates a 1-120Hz master trigger to drive all accelerator components synchronously from 60Hz AC line and 238MHz RF. The TDU is an 8ch 24bit delay counter to generate required timing signals for each component using the master trigger from the MTU. The TDU uses 238MHz RF as a counter clock and uses 5712MHz RF to recover the circuit jitter and to synchronize to the electron beam. The time jitter of 0.71ps in the TDU was achieved. We measured the time jitter between an electron beam and a 5712MHz RF that is a main acceleration RF frequency, and obtained 0.34ps. This demonstrates good stability of SPA.
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| TUPMA036 | Comparative Studies of Electron Sources for a Free Electron Laser at PSI | emittance, electron, cathode, 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, simulation, cathode | 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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| TUPMA046 | Future Light Source based on Energy Recovery Linac in Japan | linac, emittance, photon, factory | 172 | ||
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After extensive discussions on the future light source of the Photon Factory at High Energy Accelerator Research Organization (KEK), it has been concluded that a 5 GeV energy recovery linac (ERL) should be the most suitable candidate to foster cutting edge experiments and support a large variety of user needs from VUV to X-rays. On the other hand, Japan Atomic Energy Agency (JAEA), which has already built a low energy (17 MeV) ERL, also proposed its own 5-6 GeV ERL as a light source. These two institutes with a participation of the members of the Institute for Solid State Physics (ISSP) of the University of Tokyo agreed to promote an ERL-based next-generation synchrotron light source in Japan. In order to realize a 5 GeV ERL, it is necessary to construct a prototype ERL with an energy of ~200 MeV and develop several critical components such as electron guns and superconducting accelerating structures. We are planning to construct together the prototype ERL at the KEK site. An R&D team for the prototype ERL is going to be organized in collaboration with accelerator scientists from the other facilities, UVSOR and SPring-8.
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| TUPMA047 | Development of a Photocathode DC Gun at JAEA-ERL | electron, emittance, cathode, 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 | cathode, 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 | cathode, 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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| TUPMA067 | New Timing System for the L-band Linear Accelerator at Osaka University | linac, laser, single-bunch, electron | 208 | ||
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A highly precise and flexible timing system has been developed for the L-band linac at ISIR, Osaka University. It provides four RF signals and several timing signals for operation of the linac and for experiments with the linac. In order to realize long-term stability of the timing system and hence operation of the linac, a rubidium atomic clock producing a 10 MHz RF signal with the fractional stability of 10-15 is used as a time base for a synthesizer used as a master oscillator for generating the acceleration frequency of 1.3 GHz. The 1.3 GHz signal from the master oscillator is directly counted to produce the four RF signals and the clock signal of the timing system at 27 MHz. The master timing signals for linac operation is taken from the AC line frequency and it is synchronized with the 27MHz clock signal precisely. To make an arbitrary delayed timing signal, a standard digital delay generator is used to make a gate signal for a GaAs RF switch, with which one of the 27MHz clock pulses is sliced out to generate the delay timing signal. Any timing signal can be made in an interval of 37 ns and the timing jitter of the delayed signal is achieved to be as short as 2 ps.
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| TUPMA076 | Design and Development of Beam Transport Elements for the BARC-ECIL Linac | linac, electron, target, focusing | 220 | ||
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A 10 MeV, 2 kW RF electron linac is under development for cargo scanning. It consists of electron gun, RF linac structure, solenoid focusing magnets, steering magnet, beam diagnostics and x-ray target. The beam diameter requirement at the target is 2mm. Since the beam is to be focused to a diameter of 2mm at the target; the transverse beam optics of the whole linac structure from gun end to the target has been simulated by solving the beam envelope equation. The beam envelope equation has been solved in radial direction by Runga-Kutta method consisting of external focusing field, RF fields, beam perveance and emittance. Various combinations of solenoid magnet focusing have been studied. It has been found that three solenoid magnets are required to focus the beam to a diameter of 2mm at the target, two between the electron gun and the linac entrance and the other between the linac exit and the target. Based on these studies two solenoid magnets has been designed and fabricated. Details of beam optics simulation results and the design of the solenoid magnets will be presented.
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| TUPMA083 | High Quantum Efficiency Photocathode for RF Guns | cathode, 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 | electron, cathode, 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 | emittance, electron, space-charge, cathode | 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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| WEPMA096 | Rejuvenation of Linac Control System for TLS | controls, linac, booster, vacuum | 458 | ||
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The pre-injector control system is a turn-key system, which was deployed 15 years ago. It is complicated and out-of-date nowadays in terms of system integration and hardware upgrading. It must be modernized to ensure its performance and reliability, and most importantly, to facilitate system maintenance. Modernization involves upgrading to enhance functionality, to prevent obsolesce of out-of-date control modules, and to replace old parts. The purpose of the upgrade plan is to replace the pre-injector control system by a new unit which has the same control environment as that of the main control system of the NSRRC accelerator facilities. Thus, the control system maintenance, as a whole, will be made substantially easier than the original system.
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| WEPMA111 | Mechanical Engineering Challenges in the Development of the FEL at RRCAT | undulator, vacuum, linac, laser | 479 | ||
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The Compact Ultrafast TErahertz Free-Electron Laser (CUTE-FEL) is being developed by BP&FEL Laboratory, RRCAT, which is designed to lase around 80 mm. Sub-systems like S-band high gradient accelerating structures, pre-buncher, buncher, pure permanent undulator etc. have already been developed and others are in advanced stage of fabrication/commissioning. In this paper we present the design, fabrication, measurements and status of various prototype developments of structures.
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| WEPMA112 | Thermal Simulations of a Photocathode R. F. Gun | simulation, vacuum, laser, electron | 482 | ||
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We are developing a photocathode linac, which uses a 2856 MHz r.f. gun, with a copper cathode driven by a 102 MHz, 266 nm laser at inclined incidence. The laser photocathode r.f. gun is a 1.6 cell BNL/SLAC/UCLA type III r.f. gun. In this paper we present the dynamic thermal cooling simulations to calculate the structural deformations and consequent frequency drift of the gun. We have done a complete r.f.-thermal-structural-r.f finite-element analysis (FEA) of the gun in that order, using ANSYS/MULTIPHYSICS. We find that with the present coolant channel design the gun can operate at up to 2 Hz without any significant change in resonant frequency and field balance.
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| WEPMA140 | Development of C-band Multi Beam Sub-booster Klystron | klystron, electron, simulation, cathode | 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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| THPMA015 | Performance of 6 MW Peak, 25kW Average Power Microwave System for 10 MeV, 10 kW Electron LINAC | klystron, linac, electron, vacuum | 649 | ||
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An S-Band microawave system with peak power capability of 6MW and average power capability of 25 kW was designed, constructed and commissioned at RRCAT. The inhouse development of various microwave technologies and pulse modulator technologies was successfully achieved and the microwave system was interfaced to the 10MeV, 10kW electron LINAC. The electron LINAC could be tested to full rated energy and power using the present microwave system. The present paper highlights the details of the performance results.
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| THPMA043 | Development of 3 MeV, 30 kW DC Electron Accelerator at EBC, Kharghar | electron, controls, vacuum, radiation | 682 | ||
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A 3 MeV, 30 kW DC industrial electron accelerator has been designed and is in advanced stage of development at EBC, Kharghar, Navi Mumbai. Electron beam at 5 keV is generated in electron gun with LaB6 cathode and is injected into accelerating column at a vacuum of 10-7 torr. After acceleration, the beam is scanned and taken out in air through a 100 cm X 7 cm titanium window for radiation processing applications. The high voltage accelerating power supply is based on a capacitive coupled parallel fed voltage multiplier scheme operating at 120 kHz. A 50 kW oscillator feeds power to high voltage multiplier column. The electron gun, accelerating column and high voltage multiplier column are housed in accelerator tank filled with SF6 gas insulation at 6 kg/sq.cm. The accelerator is located in a RCC building with product conveyor for handling products. A central computerized control system is adopted for operation of the accelerator. Accelerator is in the advance stage of commissioning. This paper describes the design details and current status of the accelerator and its various subsystems.
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| THPMA094 | SF6 Gas Handling System for 3 MeV, 30 kW Industrial Electron Beam Accelerator at EBC, Kharghar, Navi Mumbai | electron, vacuum, controls, instrumentation | 779 | ||
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The 3 MeV Accelerator Project involves designing, fabrication, installation and commissioning of a 3 MeV, 30 kW Industrial Electron Beam Accelerator with a terminal voltage of 3 MV and is housed inside the Electron Beam Centre building at Kharghar, Navi Mumbai. The Accelerator has capability of delivering electron beam of 3 MeV energy for radiation processing applications. For ecological and economical reason, the SF6 gas is reincorporated into closed cycle because gas should not be released into the atmosphere. The aim of the SF6 gas handling system is to introduce the gas at high pressure to the accelerator tank after evacuation and to bring back into the storage tanks with minimum loss. The gas handling system also provides purification of gas, prevention from mixing with air or any other substances, which may contaminate and thus bring down the high voltage insulation characteristics of the gas. This paper discusses about mechanical design, fabrication, testing and safety of different components of SF6 gas handling system such as gas piping, non lubricating compressor, dryer, vacuum pump, dust & oil filters, storage tanks etc.
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| THPMA126 | Beam Optics Design for DC High-voltage Accelerator of MW Level | cathode, 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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