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MOPAN014 | DESY and ILC EDMS: Engineering Data Management for Large Scientific Projects | controls, feedback, simulation | 173 | |||||
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DESY is using an Engineering Data Management System (EDMS) for supporting the XFEL and PETRA III projects. The system offers a wide range of applications for managing complexity: It enables 3D CAD design collaboration, supports the manufacturing and preparation processes of s.c. cavities and provides general project documentation. The system is now also adopted by the ILC for the collaborative 3D CAD design of cryomodules in the three regions and for change management of the baseline configuration document. The DESY EDMS is based on a commercial system which has been customized to the specific needs of large scientific projects, making it a unique system. In addition to general engineering requirements, the EDMS supports ad-hoc teamwork, provides mechanisms for process industrialization and offers powerful yet easy-to-use web frontends. The paper gives an overview of the EDMS capabilities and reports experience and benefits of using the EDMS.
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MOPAN108 | The FONT4 ILC Intra-train Beam-based Digital Feedback System Prototype | feedback, kicker, electron, positron | 416 | |||||
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We present the design of the FONT4 intra-train beam-based digital position feedback system prototype. The system incorporates a fast analogue beam position monitor front-end signal processor, a digital feedback board, and a fast kicker-driver amplifier. The system latency goal is less than 150ns. We report preliminary results of beam tests at the Accelerator Test Facility (ATF) at KEK using electron bunches separated by c. 150ns.
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MOPAN109 | Turnaround Feed-Forward Correction at the ILC | kicker, extraction, damping, septum | 419 | |||||
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Funding: The Commission of European Communities under 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899, and by the UK Particle Physics & Astronomy Research Council. |
The RTML turnaround feed-forward correction scheme, as proposed in the ILC Baseline Configuration Document, is considered. Instabilities in the challenging Damping Ring extraction kicker system may give rise to betatron bunch-by-bunch jitter and position drift across the bunch train. A system is outlined in which the bunch trajectory is measured with an upstream pair of BPMs and corrected with a pair of downstream fast kickers. The beam turnaround time allows signal processing and calculation of the correction. A feed-forward algorithm is formulated and expressions are derived for the main system parameters and procedures: dynamic range, maximal kicker voltage, gain compression error, BPM resolution, system zero offset stability, BPM-to-kicker matrix measurement, feed-forward gain adjustment. This analysis will enable further consideration of system tolerances, and provides a basis for an engineering design. |
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MOPAS069 | Analysis of a Compact Circular TE 01-Rectangular TE 02 Waveguide Mode Converter | simulation, coupling, scattering, collider | 587 | |||||
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An analysis method for a three section mode transformer that converts a TE 01 circular waveguide mode to a TE 02 rectangular waveguide mode will be presented. Experimental results for this taper were earlier published in*. The middle section is a cylinder with a wall radius defined by rw = a(1 + d cos(2Θ)), where a is the radius of the circular guide and d is a design parameter. This cylinder is connected on either side to a circular waveguide and a rectangular waveguide section respectively, through tapered waveguide sections. In this analysis we used a perturbation technique where the rectangular waveguide section's wall radius is treated as a Fourier series expansion with a, the fundamental radius and d the perturbation parameter. By applying the proper boundary conditions we optimize the taper dimensions to minimize conversion into spurious modes.
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*S. G. Tantawi et al., Physical Review Special Topics Accelerator and Beams. 8, 042002 (2005) |
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MOPAS086 | FPGA Based ILC Cavity Simulator | simulation, controls, superconducting-RF, resonance | 632 | |||||
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In the proposed International Linear Collider (ILC) design, the Low Level RF (LLRF) control system plays the important role of maintaining the proper phase and amplitude information for the RF field inside the superconducting cavities. The high operational overhead of the high power cryogenic hardware and the risk of its damage during the control hardware tests make it necessary to have a LLRF test bed independent of the real hardware. Thus, we have developed a Real Time Simulator (RTS), an FPGA based ILC RF unit simulator, which will be useful for the testing and commissioning of the Low Level RF control system, including the exception handling capabilities, and possibly as a noiseless behavioral reference for each cryomodule during operation. The RTS has been implemented on a Lyrtech VHS-ADAC board. It includes effects such as Lorentz Detuning and presently an overall latency lower than 200 nanoseconds has been achieved. The status of the RTS and the conclusions derived from the simulations will be reported, along with LLRF interface tests results.
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TUYAB01 | Transverse-transverse and Transverse-longitudinal Phase Space Converters for Tailoring Beam Phase Spaces | emittance, electron, radiation, coupling | 775 | |||||
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This talk covers basic beam dynamics theory, including emittance converters and the flat beam technique, and also new ideas for transverse-longitudinal coupling. The work done in collaboration with SLAC, FNAL, and NIU, including a preliminary experiment performed at Fermilab, is to be presented.
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TUXC03 | Design and Status of the XFEL RF System | klystron, linac, electron, controls | 841 | |||||
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The RF system of the European XFEL under construction at present at DESY in Hamburg, Germany, consists of 27 RF stations. At a later point of time the number might be increased to 31. The RF system provides RF power at 1.3GHz for the superconducting cavities of the main linear accelerator, the cavities of the injector and the RF gun. Each station consists of a 10MW multiple beam klystron, a HV pulse modulator, HV pulse cables, a pulse transformer, an interlock system, a low level RF system, a waveguide distribution system and a number of auxiliary power supplies. This paper describes the layout of the RF system and summarizes the design and status of the main high power components.
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TUOAC02 | Development and Testing of the ILC Marx Modulator | controls, shielding, klystron, vacuum | 849 | |||||
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Funding: Work supported by the U. S. Department of Energy under contract DE-AC02-76SF00515 |
Construction of the ILC 'Reference Design' Marx Modulator is complete, and testing is currently underway at SLAC. The Reference Design prototype is oil-free, air-cooled, and capable of delivering 120kV, 140A pulses at a rate of 5Hz. Total energy per pulse is 23,500 joules. Projected efficiency is greater than 96%. The Reference Design Marx modulator employs a stack of 12kV Marx modules that generate high-voltage output pulses directly from a 12kV input supply voltage. This direct switching eliminates the requirement for a massive transformer and reduces the capacitor bank size by more than a factor of four, yielding a considerably cheaper and more compact mechanical solution. Advantages of the Marx design include higher efficiency, smaller physical size, and a modular architecture that provides greater reliability and cost-effective PC board-level integration. This paper outlines the ILC Marx Modulator Development Program currently underway at SLAC. The paper presents detailed mechanical and electrical design diagrams, 3D field simulations, and operational test results for the full-scale Reference Design modulator prototype. |
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TUZAC01 | The ILC Control System Design | controls, feedback, monitoring, linac | 868 | |||||
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Funding: Work supported in the U. S. by the U. S. Department of Energy under contract Nos. DE-AC02-06CH11357, DE-AC02-76CH03000, and DE-AC02-76SF00515. |
The scale and performance parameters of the ILC require new thinking in regards to control system design. This design work has begun quite early in comparison to most accelerator projects, with the goal of uniquely high overall accelerator availability. Among the design challenges are high control system availability, timing reference distribution, standardization of interfaces, operability, and maintainability. We present the current state of the design and take a prospective look at ongoing research and development projects. |
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TUPMN094 | Development of a Model Superconducting Helical Undulator for the ILC Positron Source | undulator, positron, collider, target | 1136 | |||||
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Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. |
Model superconducting helical undulators are under development for the proposed International Linear Collider (ILC) positron source. The undulator requires high-permeability steel poles and superconducting coils to meet the ILC parameters. A fabrication method for steel poles on a nonmagnetic beam chamber was developed. A model undulator with a period length of 14 mm and Nb3Sn coils was fabricated. Both ends of the model were designed to provide for continuous winding of a single conductor with 39 turns per helix. A 10-mm-period model was designed and is in the fabrication process. The 14-mm-period model may be used in the development of a cryogenic magnetic measurement system. Details of the fabrication and test results will be presented. |
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WEXAB01 | ILC Reference Design and Challenges | collider, superconducting-RF | 1944 | |||||
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The International Linear Collider (ILC) is a 500 GeV center-of-mass electron-positron linear collider based on 1.3 GHz superconducting rf. For the past two years, the ILC design has been developed by an international collaboration, the Global Design Effort. A draft Reference Design Report (RDR) for the ILC was released in February 2007 and, after international review, the final draft will be published in mid-July, 2007. This talk will describe the ILC design along with the outstanding R&D and engineering challenges. The next step is to complete an Engineering Design (EDR) by 2010, and plans for this phase will also be discussed.
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WEOAAB01 | Spin Transport in the International Linear Collider | polarization, emittance, coupling, collider | 1955 | |||||
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Funding: Work supported by the U. S. National Science Foundation and the U. S. Department of Energy. |
Polarized positron and electron beams are ideal for searching for new physics at the International Linear Collider (ILC). In order to properly orient and preserve the polarization of both beams at the Interaction Point (IP) the beam polarization must be manipulated by a series of spin rotators along the beam line. Furthermore, the polarization for both beams should be known with a relative uncertainty of about 0.5% or better, therefore, all sources of depolarization along the ILC should be identified. We report on a spin rotator design for the ILC and polarization studies between Damping Ring extraction and the Interaction Point. |
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WEOAAB02 | The Optimized Bunch Compressor for the International Linear Collider | wiggler, linac, damping, emittance | 1958 | |||||
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The International Linear Collider (ILC) utilizes a two stage Bunch Compressor (BC) that compresses the RMS bunch length from 9 mm to 200 to 300 micrometers before sending the electron beam to the Main Linac. This paper reports on the new design of the optimized BC wiggler. It was reduced in length by more than 30 %. The introduction of nonzero dispersion slope in the BC wigglers enabled them to generate the required compression while having a small SR emittance growth, a tunability range of over a factor of 2 in each wiggler, and less than 3 % RMS energy spread throughout the entire system.
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WEYAB01 | Overview of Industrialization Strategies for ILC | superconducting-RF, linac, collider, electron | 1961 | |||||
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ILC is by far the largest and most challenging application of superconducting RF accelerator technology. Starting from the experience with TESLA and XFEL I will describe the level of industrial competence in the three global regions (Asia, America and Europe). In particular I will refer to the state of the art of cavity fabrication, module assembly and auxiliary components as well as to the synergy with the XFEL project. I will use the fabrication experience with SC magnets for LHC at CERN as benchmark for industrialization strategies for ILC.
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WEOBAB02 | Studies of Emittance Bumps and Adaptive Alignment method for ILC Main Linac | emittance, alignment, feedback, linac | 1973 | |||||
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Funding: U. S. Department of Energy |
International Linear Collider (ILC) is a proposed electron-positron accelerator requiring very small spot-size at the interaction point, and thus necessitates very tight tolerances on beamline elements. For static tuning of the machine a few methods like dispersion-free steering (DFS) or kick minimization (KM) techniques was proposed. The further suppression of emittance growth can be achieved by using close orbit emittance bumps. Stability of ILC is determined by the stability of the site, additional noises of beamline component, energy and kicker jitter and performance of the train-to-train and intra-train feedback. We discuss the performances of the Adaptive Alignment technique, which keeps accelerator dynamically aligned in presence of ground motion an technical noises. This presentation is an overview of two posters THPMN107 and THPMN108, presented at PAC07. |
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WEOCAB02 | Automatic Luminosity Optimisation of the ILC Head-On BDS | luminosity, quadrupole, collider, extraction | 1988 | |||||
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Funding: EUROTeV Project Contract no.011899 RIDS |
With the local chromaticity correction scheme, the luminosity optimisation of the beam delivery systems of the e+ e- International Linear Collider (ILC) project is challenging. A manual optimization is a long and complex process and its automation becomes a necessity. Recent works have shown that it was possible to employ a simplex minimization method, applied to the beam size calculation at the Interaction Point (IP), to reach this objective automatically *. To achieve this goal in the ILC case, we have developed a minimization code which uses analytical computations of the IP beam sizes based on external code results, TRANSPORT** or MADX (with PTC extension)***. Two minimization algorithms can be employed. The maximum luminosity reached and the convergence time of the two codes and algorithms are compared. We also used the code TRACEWIN which tracks a particle cloud and minimise the rms beam spot sizes at IP to optimise the luminosity, and we compare with the previous results.
* Non-linear optimization of beam lines, R. Tomas, CLIC Note 659** Third-Order TRANSPORT with MAD Input, D. C. Carey, K. L. Brown and F. Rothacker, FERMILAB-Pub-98/310*** MADX User's Guide CERN |
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WEPMN026 | Test Operation of Ball-Screw-Type Tuner for Low-Loss High-Gradient Superconducting Cavity in a Cryomodule | resonance, controls, damping, linac | 2104 | |||||
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We are constructing a Superconducting RF Test Facility (STF) at KEK as an R&D for ILC accelerator. In STF, four Low-Loss (LL) type 9-cell cavities will be installed into a cryomodule. We are developing ball-screw-type tuner for these cavities aiming at the accelerating gradient of 45 MV/m. At the end of 2006, we installed one LL 9-cell cavity dressed with the ball-screw tuner into the cryomodule. It will be operated without beam in 2007. This paper describes the results of the first operation of the ball-screw tuner for LL 9-cell cavity in the cryomodule of STF.
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WEPMN027 | Construction of the Baseline SC Cavity System for STF at KEK | coupling, pick-up, radiation, controls | 2107 | |||||
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Construction of STF (Superconducting RF Test Facility) is being carried out at KEK. Four-cavity system including 9-cell baseline cavities (TESLA-type), input couplers and frequency tuners has been developed and will be installed in a 6 m cryomodule. The peculiarity of the STF baseline cavity system is a very stiff design in a jacket and tuner system, which can relax the effect of Lorentz detuning in a pulsed operation. Performance tests of four 9-cell cavities have been carried out repeatedly in a vertical cryostat, and the attained accelerating gradients reached to about 20 MV/m with no field emission in each cavity. High power input couplers with two planar rf windows were fabricated, and the rf processing test with a pulsed klystron was successfully carried out up to 1.0 MW with 1.5 msec and 5 Hz without any troubles. Assembly of the cryomodule including one 9-cell baseline cavity had completed (STF phase 0.5), and the first cool-down test is scheduled in March, 2007.
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WEPMN029 | Status of the Low-Level RF System at KEK-STF | feedback, controls, linac, klystron | 2113 | |||||
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RF field stabilities of less than 0.3%, 0.3deg. are required at STF llrf system. In order to satisfy these requirements, digital FB system using a FPGA is adopted. The FB system consists of a FPGA (VirtexIIPro30) with ten 16-bit ADCs and two 14-bit DACs. The rf (1.3 GHz) probe signals are downconverted to the IF (10 MHz) and directly acquired at ADCs. Total 8 cavities will be installed at STF-Phase 1 in 2007 and vector sum control of 8 cavity signals will be carried out. The performance of the FB system is examined with electric cavity simulators prior to the rf operation.
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WEPMN047 | Electro-polished Cavities Using China Ningxia Large Grain Niobium Material | vacuum, superconducting-RF, collider, electron | 2143 | |||||
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For the International Linear Collider (ILC), superconducting RF cavity technology was chosen. The superconducting cavity is made of polycrystalline niobium material so far. However, the material cost is high and the cavity performance has a rather scatter now. Large grain niobium (LG) cavity is an excellent idea because it simplifies the production process and results in less expensive. JLAB and DESY are pushing the R&D in last two years. KEK also has started to investigate LG. Three cavities with Ichiro shape were made of Chinese large grain niobium (Ningxia). A series of vertical tests has been carried out on several different surfaces treatment procedures by electropolishing. One cavity has reached the high gradient of more than 43 MV/m repeatedly. Other two cavities are still under testing. In this paper, the features of LG on electropolishing will be described with Ningxia large grain niobium material.
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WEPMN048 | Measurement for the Kanthal Alloy Used for Collinear Load and S-band Load Design | resonance, electron, vacuum, emittance | 2146 | |||||
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Funding: National Nature Science Foundation No.10675116 No.10375060 |
We have developed the mathod to determine the permittivity and permeability of Kanthal alloy available. The alloy is coated on the inside walls of disk-loaded cavities,which is used for the collinear load. The collinear load absorbs the remaining rf-power over the last cells of the section while still accelerating the beam. Based on the experimental results of the permittivity and permeability,the computation study of the constant power-loss collinear load has been made by Microwave Studio. The design data about the S-band collinear load are present. |
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WEPMN050 | Model Cavity Investigations and Calculations on HOM for a X-Band Hybrid Dielectric-Iris-Loaded Accelerating Structure | dipole, resonance, collider, coupling | 2149 | |||||
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Funding: National Nature Science Foundation of China, Grant No.10375060 and No.10675116 |
Some model cavities have been further developed and investigated for a X-band (f=9.37GHz) hybrid dielectric-iris-loaded accelerating structure based on the calculated results about the effect of the dimension tolerance on the RF properties. The dispersion curve fitted by using the measurement value is consistent with the one calculated. The r/Q values of the dipole modes have been calculated by the Mafia code. The theoretical results show that the r/Q values of dipole modes for the new accelerating structure are lower than those for the iris-load accelerating structure. |
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WEPMN072 | Material Selection and Characterization for High Gradient RF Applications | laser, target, collider, insertion | 2197 | |||||
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The selection of candidate materials for the accelerating cavities of the Compact LInear Collider (CLIC) is carried out in parallel with high power RF testing. The DC breakdown field of copper, copper alloys, refractory metals, titanium and aluminium have been measured with a dedicated setup. Higher maximum fields are obtained for refractory metals and for titanium, which exhibits important damages after conditioning. Fatigue behaviour of copper alloys has been studied for surface and bulk by pulsed laser irradiation and ultrasonic excitation, respectively. The selected copper alloys show consistently higher fatigue resistance than copper in both experiments. RF tests are planned. In order to obtain the best local properties a bi-metallic assembly is being studied for the accelerating structures. The mechanical strength of junctions of molybdenum and copper-zirconium C15000, made either by Hot Isostatic Pressing or explosion bonding was evaluated. The reliability of the results obtained with either technique should be improved. Testing in DC and RF is continued in order to select materials for a bi-metal exhibiting superior properties with respect to the combination C15000-Mo.
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WEPMN099 | Production of 325 MHz Single Spoke Resonators at FNAL | vacuum, linac, target, proton | 2262 | |||||
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Funding: US Department of Energy |
The High Intensity Neutrino Source (HINS) project represents the current effort at Fermi National Accelerator Laboratory to produce an 8-GeV proton linac based on about 400 independently phased superconducting resonators. Eighteen β=0.21 single spoke resonators, operating at 325 MHz, comprise the first stage of the linac cold section. We are presenting the production status of the first two of these resonators and the performance of the tuning mechanism prototype. In particular, we will report on the construction phases, the pre-weld tuning process and the comparison of low power RF measurements with calculations made using Microwave Studio*.
* CST MICROWAVE STUDIO (CST MWS), http://www.cst.com/ |
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WEPMN113 | A High Voltage Hard Switch Modulator for the International Linear Collider | power-supply, controls, cathode, collider | 2301 | |||||
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Under the U. S. DOE SBIR program, Diversified Technologies, Inc. (DTI) is developing a modulator to supply 135 kV, 165A, 1.5 ms pulses for the International Linear Collider. The hard-switch modulator, using DTI?s solid-state switches, will accommodate the long pulse-length required by the L-band (1.3 GHz) klystrons. To achieve required pulse flatness (0.5% at 5 Hz) without a large capacitor bank, a bouncer circuit is used to compensate the voltage droop. An LC ringer, switched separately from the main HV capacitor bank, is employed. The main storage capacitor is charged by a 185 kW DTI inverter driving a four-stage voltage multiplier. The bouncer capacitor is charged by a commercial high voltage supply. A multi-stage, high voltage switch connects the main capacitor to the load during the linear portion of the bouncer ringing transient. The inverter transformers, multiplier, bouncer inductor, capacitor, high voltage switches, main capacitor bank (90kJ), and voltage and current diagnostic probes are completely housed in oil-filled tanks. This paper describes the structure and operating theory of this switching system, and reports on its construction and initial testing.
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WEPMS006 | High Gradient Studies for ILC with Single Cell Re-entrant Shape and Elliptical Shape Cavities made of Fine-grain and Large-grain Niobium | vacuum, collider, electron | 2337 | |||||
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Funding: Work supported by DOE |
Based on the encouraging results of the first 1300 MHz 70 mm aperture single cell re-entrant cavities*, we continue the high gradient studies for ILC with new re-entrant cavities made of fine-grain as well as large-grain niobium. These new cavities have smaller aperture of 60 mm, providing a further reduced Hpk/Eacc or a further improved ultimate gradient. Four 1300 MHz 60 mm aperture re-entrant cavities are made, two out of fine grain niobium and the other two out of large-grain niobium. In addition, two elliptical shape 1500 MHz cavities are also made out of large-grain niobium. We present the testing results of these cavities.
* R. L. Geng et al., PAC2005, p.653. |
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WEPMS026 | Improved Tuning Methods for Converter-Modulators | feedback, collider, impedance, operational-performance | 2391 | |||||
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Funding: This work is supported by the office of Basic Energy Sciences and the Office of Science of the Department of Energy |
The converter-modulator is a resonant power conditioning configuration that is optimized for a particular load impedance or parameter space. Although traction motor IGBT's are typically used for hard-switching application in the 1 kHz regime, the present use of high-power (10 - 15 MW) converter-modulators have used a 20 kHz resonant switching topology. This presents design challenges to maintain efficient and reliable switching characteristics for the IGBT's. Improved tuning methods and circuit topological changes now offer a significant reduction in IGBT switching losses as compared to those used with the Spallation Neutron Source (SNS) design (perhaps by 10). These circuit and topology changes should also permit Pulse Width Modulation (PWM) of the modulator output voltage to provide a regulated voltage without anomalous IGBT switching characteristics. This paper will review the results of this investigation based on models developed from the SNS converter-modulator operational data. |
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WEPMS028 | Converter-Modulator Design and Operations for the ILC L-band Test Stand | klystron, impedance, collider | 2397 | |||||
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Funding: This work supported by Stanford Linear Accelerator Center, Oak Ridge National Laboratory, and the Department of Energy. |
To facilitate a rapid response to the International Linear Collider (ILC) L-Band development program at SLAC, a spare converter-modulator was shipped from Los Alamos. This modulator was to be a spare for the Spallation Neutron Source (SNS) accelerator at ORNL. The ILC application requires a 33% higher peak output power (15 MW) and output current (130 Amp). This presents significant design challenges to modify the existing hardware and yet maintain switching parameters and thermal cycling within the semiconductor component ratings. To minimize IGBT commutation and free-wheeling diode currents, a different set of optimizations, as compared to the SNS design, were used to tune the resonant switching networks. Additional complexities arose as nanocrystalline cores with different performance characteristics (as compared to SNS), were used to fabricate the resonant "boost" transformers. This paper will describe the electrical design, system modifications, modeling efforts, and resulting electrical performance as implemented for the ILC L-band test stand. |
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WEPMS031 | Development of a Temperature Mapping System for 1.3-GHz 9-Cell SRF Cavities | superconductivity, diagnostics, radio-frequency, collider | 2406 | |||||
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The mapping of outer wall temperature during the vertical test of a superconducting radio-frequency (SRF) cavity has been one of the most useful tools to detect bad spots of the cavity. However, few systems except a rotating-arm type one have been developed so far for 9-cell cavities. Since it will be an essential tool to identify the failure of the cavities, we started to develop a fix-type temperature mapping system that will enable us to map the temperature of 9-cell cavities in a much shorter time than rotating-arm type. This paper describes the design, status of the development and hopefully some results of the mapping of actual cavities.
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WEPMS032 | Pre-conceptual Design of Automated Systems for SRF Cavity Assembly and Optical Inspection | superconductivity, radio-frequency, feedback, vacuum | 2409 | |||||
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The International Linear Collider (ILC) will require ~20,000 Superconducting Radio- Frequency (SRF) cavities. Improving the yield of high-gradient (>35 MV/m) cavities is currently one of the most critical issues for the ILC. The LANL has been tasked to analyze the failure and feedback the results to the industry and academia. We have started an effort to develop a pre-conceptual design of an automated system to optically inspect the inner surface that showed heating with a thermometry system. We have also started a pre-conceptual design of an automated system for assembling and sealing the flanges after high-pressure rinsing in the clean room. This could reduce the chance of particle contamination due to touch labor, leading to a field emission free cavities and higher yield of high-gradient cavities.
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WEPMS037 | RF Distribution Optimization in the Main Linacs of the ILC | linac, controls, damping, coupling | 2424 | |||||
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Funding: Work supported by the U. S. Department of Energy under contract DE-AC02-76SF00515. |
The nominal design gradient for the ILC is 31.5 MV/m, but the L-band superconducting cavities built to date have demonstrated a range in sustainable gradient extending below this goal, limited by Q-dropoff and quenching. An economically feasible cavity acceptance rate will include in the linacs a certain percentage of sub-performing cavities. We examine how, with a customizable RF distribution scheme, one can most efficiently distribute power from one klystron amongst 24 nine-cell cavities. The nominal cavity fills to the design gradient at the time the beam arrives, after which the beamloading voltage exactly cancels any further rise, yielding constant gradient during the bunch train. Along with adjustable RF power, we assume adjustable cavity coupling, or loaded quality factor, so that the gradient can be leveled in non-nominal cavities, to avoid quench-inducing overshoots. We explore these and related issues for the ILC linac high-power RF. |
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WEPMS040 | Active RF Pulse Compression Using Electrically Controlled Semiconductor Switches | simulation, coupling, laser, resonance | 2433 | |||||
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In this paper, we will present our recent results on the research of the ultrafast high power RF switches based on silicon. We have developed a switch module at X-band which can use a silicon window as the switch, and scaled it to 30GHz for the CLIC application. The switching is realized by generation of carriers in the bulk silicon. The carriers can be generated electrically or/and optically. The electrically controlled switches use PIN diodes to inject carrier. We have built the PIN diode switches at X-band, with <300ns switching time. The optically controlled switches use powerful laser to excite carriers. By combining the laser excitation and electrical carrier generation, significant reduction in the required power of both the laser and the electrical driver is expected. High power test is under going.
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WEPMS043 | An RF Waveguide Distribution System for the ILC Test Accelerator at NML | coupling, klystron, linac, collider | 2442 | |||||
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Funding: Work supported by the U. S. Department of Energy under contract DE-AC02-76SF00515. |
An ILC R&D facility is being constructed in the NML building at Fermilab which, in addition to an injector and beam dump with spectrometer, will contain up to three cryomodules worth of ILC-type superconducting 9-cell cavities, 24 in all. This linac will be powered by a single klystron. As part of SLAC?s contribution to this project, we will provide a distribution network in WR650 waveguide to the various cavity couplers. In addition to commercial waveguide components and circulators and loads developed for TESLA, this sytem will include adjustable tap-offs, and customized hybrids. In one configuration, the circulators will be removed to test pair-wise cancellation of cavity reflections through hybrids. The system will be pressurized with nitrogen to 3 bar absolute to avoid the need for SF6 at windows or circulator. The full distribution for the first cryomodule will be delivered and installed later this year. We describe the design of the system and completed RF testing. |
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WEPMS051 | One Channel, Multi-Mode Active Pulse Compressor | plasma, collider, coupling, scattering | 2460 | |||||
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Funding: Research sponsored in part by US DoE. |
Basic studies of factors that limit RF fields in warm accelerator structures require experiments at RF power that can be produced using pulse compression. This approach is being implemented to compress output pulses from the Yale/Omega-P 34-GHz magnicon to produce ~100-200 MW, 100 ns pulses. A new approach for passive pulse compression is a SLED-II type circuit operating with axisymmetrical modes of the TE0n type that requires only a single channel instead of the usual double channel scheme. This allows avoidance of a 3-dB coupler and need for simultaneous fine tuning of two channels. A 30 GHz passive prototype was tested at low power level in order to demonstrate key principles. The prototype showed a power gain 3,8 at a compression ratio 6:1 for an efficiency 63%. An active version of the one-channel pulse compressor is also suggested. It is attractive due to a possibility to achieve higher power gain. The mentioned active version naturally requires an electrically controlled coupler. In particular, as active elements of the coupler we suggest to use gas filled discharge tubes or ferroelectrics which have well recommended itself at 11.4 GHz experiments. |
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WEPMS083 | A Low-Voltage Klystron for the ILC and ILC Testing Program | klystron, gun, simulation, cathode | 2526 | |||||
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Funding: Work supported by the US Department of Energy. |
FAR-TECH, Inc. is developing and building a 36 kV, 830 kW klystron for the International Linear Collider (ILC) testing program. A variant of the tube can also be used to supply RF energy for a 2-3 meter section of ILC. The tube design is of the multiple-beam klystron (MBK) type, using ten beams with confined flow focusing. The design optimizes small tube size and low cost. The initial prototype will use an electromagnet, but the design allows for the eventual use of a permanent magnet solenoid. An efficiency of 65% is expected. We will present the design and status of the construction of the klystron and supporting systems. |
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WEPMS085 | A 17 GHz High Gradient Linac having Stainless Steel Surfaces in the High Intensity Magnetic and Electric Field Regions of the Structure | linac, feedback, coupling, collider | 2532 | |||||
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Funding: Work performed under the auspices of the U. S. Department of Energy SBIR Grant No. DE-FG02-05ER84362. |
To avoid surface erosion damage and to assist in understanding RF breakdown limitations imposed on high gradient linac operation, a gradient hardened structure is being fabricated having high temperature brazed and machined stainless steel surfaces located in the high E-field region of the beam apertures and in the high H-field regions of the racetrack shaped coupling cavities. The microwave design parameters and physical dimensions of this 17GHz, 2pi/3 mode, 22-cavity structure were established specifically to allow comparison of its high gradient performance to that of a similar all-copper structure tested under identical conditions, using an existing 4X power amplifying, RF recirculating dual ring system. Use of the 6X thicker skin depth material, the resulting de-Q-ing effects and the minimal reduction of beam energy (2%) associated with the strategically located lossy surfaces are discussed; fabrication techniques are described; and design parameters of the gradient hardened linac and the 17GHz power amplifying system are presented. |
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THXKI01 | R&D in RF Superconductivity to Support the International Linear Collider | collider, acceleration, insertion, superconductivity | 2559 | |||||
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ILC-related R&D in SRF spans a broad range of topics, ranging from the search for high gradients through improved processes and cavity geometries, through the use of new materials (large-grain and single-crystal niobium metal) and development of superconducting joints to enable superstructure concepts and minimum length vacuum joints. This talk will review the status of the global ILC SRF R&D program and discuss plans for the future.
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THOBKI02 | Marx Bank Technology for the International Linear Collider | power-supply, controls, collider, klystron | 2590 | |||||
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In August, 2004, the international science community formally backed the development of a superconducting linear accelerator named the International Linear Collider (ILC). It is expected that the accelerator will employ klystrons operating in the range of 110-135 kV, 120-166 A, and 1.5 ms pulsewidth. Due to the accelerator's long pulse length and high power, focusing on power supply and energy storage alternatives promises to yield significant reductions in acquisition costs. Diversified Technologies, Inc. (DTI) has developed a high power, solid-state Marx Bank topology, offering an optimal, silicon-efficient technology for the ILC modulators and power supplies. We estimate the Marx topology can deliver equivalent performance and yield acquisition cost savings of 25-50% versus presently proposed alternatives. In this paper DTI will describe the Marx based technology as it is applied to ILC power systems design, and review recent progress in the engineering of the prototype transmitter.
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THICKI03 | Large Helium Refrigeration Plant Operating Experience | cryogenics, extraction, collider | 2700 | |||||
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Air Products and Linde have signed a Teaming Agreement to pursue refrigeration services for the proposed International Linear Collider. Air Products brings unique helium liquefaction and refrigeration capabilities to the table through its operation of one third of the world's cryogenic liquefiers and ownership of Gardner Cryogenics the world's leading developer, designer and manufacturer of liquid helium storage, distribution and transportation equipment. Air Products is an industry leader throughout the helium supply chain, from providing technology for crude helium extraction from natural gas, to delivering liquid helium to end users, as well as through MRI helium supply activities. Air Products has designed and installed most of the world's crude helium extraction plants. Linde designs and builds cryogenic plants and systems for the most varied fields, from fundamental research and industrial HTS applications to the cooling of superconducting accelerators and cold neutron sources, fusion and fission applications and the industrial liquefaction of helium and hydrogen.
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THPMN006 | Modification and Measurement of the Adjustable Permanent Magnet Quadrupole for the Final Focus in a Linear Collider | quadrupole, permanent-magnet, collider, optics | 2719 | |||||
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Funding: This research was partially supported by JSPS, Grant-in-Aid for Scientific Research, 14204023-2002, 18204023-2006 and the U. S. DOE under contract DE-AC02-76SF00515. |
An adjustable permanent magnet quadrupole has been developed for the final focus in an electron-positron linear collider. The design has two concentric rings of permanent magnets. Recent activities include a newly fabricated inner ring that demonstrates the strongest field gradient at a small bore diameter of 15mm and a new magnetic field measurement system based on a rotating coil. The prospects of the R&D will be discussed. |
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THPMN010 | GUINEA-PIG++ : An Upgraded Version of the Linear Collider Beam-Beam Interaction Simulation Code GUINEA-PIG | simulation, luminosity, background, collider | 2728 | |||||
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GUINEA-PIG++ is a newly developed object-oriented version of the Linear Collider beam-beam simulation program GUINEA-PIG. The main goals of this project are to provide a reliable, modular, documented and versatile framework enabling convenient implementation of new features and functionalities. Examples of improvements described in this paper are an easy interface to study the impact of electromagnetic effects on Bhabha event selections, a treatment of spin depolarization effects, automatic consistency checks and adjustments of internal computational parameters, upgraded input/output and user interface, an optimised setup for massive production on distributed computing GRIDs. A possible setup to perform fast parallelised computations is also discussed.
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THPMN065 | Laser Collimation for Linear Colliders | laser, collimation, electron, collider | 2856 | |||||
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We explore the possibility of laser-based postlinac beam collimation in future linear colliders. A laser employed as a spoiler can neither be 'destroyed' by the beam impact and nor generate collimator wake fields. In addition, the postlinac collimation section, presently the longest part of linear-collider beam delivery systems, can be shortened. In this paper, we investigate different types of laser modes for use as spoiler. Suitable laser beam parameters and modes are discussed for collimation in both CLIC and ILC.
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THPMN068 | Beam Impact Studies on ILC Collimators | radiation, collider, positron, electron | 2859 | |||||
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Funding: CCLRC The Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. |
Spoilers in the ILC Beam Delivery System are required to survive without failure a minimum of 1-2 direct impacts from each energetic electron or positron bunch of charged particles, in addition to maintaining low geometric and resistive wall wake fields. The transient shock wave resulting from rapid localised beam heating and its implications for spoiler design are studied using ANSYS. Shockwave propagation is modelled in 2 dimensions showing the effect of dilatational shockwaves striking free surfaces, producing reflected dilatational and distortional waves. The implication of these relflected waves on the damage of the collimators is also discussed. |
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THPMN070 | Development of a Full Scale Superconducting Undulator Module for the ILC Positron Source | undulator, positron, vacuum, radiation | 2862 | |||||
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. |
An undulator based positron source is a baseline for the International Linear Collider (ILC). The HeliCal collaboration in the UK is working on the development of a full scale 4-m long undulator module. Several prototypes have been built and tested in the R&D phase of the programme that culminated in the development of manufacturing techniques suitable for construction of the first full scale undulator sections. This paper details the design and the construction status of 4-m long undulator module. |
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THPMN071 | Status of R&D on a Superconducting Helical Undulator for the ILC Positron Source | undulator, positron, vacuum, collider | 2865 | |||||
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Funding: This work is supported in part by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899. |
An undulator based positron source is a baseline for the International Linear Collider (ILC). The HeliCal collaboration in the UK is carrying out an R&D programme on a short period supercoducting helical undulator with the goal to develop manufacturing technique as well as modelling and measurement techniques. Several undulator prototypes have been built and successfully tested. This paper summarizes the results of the R&D phase of the project. |
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THPMN087 | Simulations of the Rotating Positron Target in the Presence of OMD Field | target, simulation, positron, optical-matching | 2909 | |||||
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Funding: US Department of Energy |
For an ILC undulator-based positron source target configuration, a strong optical matching device (OMD) field is needed inside the target to increase the positron yield (by more than 40%)[1]. It is also required that the positron target is constantly rotated to reduce thermal and radiation damage. We report on a simulation of the rotating metal target wheel under a strong magnetic field. By rearranging Maxwell?s equations for a rotating frame and using FEMLAB, we have solved the detailed magnetic field distribution and eddy current of a rotating metal disk in magnetic field, and so the required power to drive the target wheel. In order to validate the simulation process, we have compared our results with previous experimental data [2] and found they are in very good agreement, but differ from previous approximate models [3]. Here we give detailed results on the proposed ILC target system, such as induced magnetic field (dipole and higher orders), eddy current distribution and the driving force requirements. The effect of these higher order fields on the positron beam dynamics is also considered. |
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THPMN089 | Enhancement of Heat Removal using Concave Liquid Metal Targets for High-Power Accelerators | target, proton, photon, collider | 2915 | |||||
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The need is increasing for development of high power targets and beam dump areas for the production of intense beams of secondary particles (IFMIF, SNS, RIA, LHC). The severe constraints arising from a MW beam power deposited on targets and absorbers, call for non-trivial procedures to dilute the beam. This study describes the development of targets and absorbers and the advantages of using flowing liquid metal in concave channels first proposed by IFMIF to raise the liquid metal boiling point by increasing the pressure in liquid supported by a centrifugal force. Such flow with a back-wall is subject to the Taylor-Couette instability. The instability can play a positive role of increasing the heat transfer from the hottest region in the target/absorber to the back-wall cooled by water. At the laminar stage of the instability with a certain wave number of vortexes, the heat transfer from a chain of vortexes to the wall increases heat removal by enhancing the convective transport inside the liquid bulk and from the bulk to the wall. Results of theoretical analysis and numerical modeling of both targets and dump areas for the IFMIF, ILC, and RIA facilities are presented.
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THPMN111 | A Kicker Driver for the International Linear Collider | kicker, damping, collider, positron | 2972 | |||||
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Diversified Technologies, Inc. (DTI), under a SBIR grant from the U. S. Department of Energy, is developing a driver for a kicker strip-line deflector which inserts and extracts charge bunches to and from the electron and positron damping rings of the International Linear Collider. The deflector requires a driver capable of 10 kV, 200 A pulses of 2 ns duration, after-pulse clamping of the deflector voltage to less than one volt within six nanoseconds, and must function at burst rates of 3 to 6 MHz. The driver must also effectively absorb high-order mode signals emerging from the deflector itself. In this paper, DTI will describe a promising approach to the design of the kicker driver involving high voltage DSRDs (Drift Step Recovery Diodes) and high voltage MOSFETs. In addition, our design approach to meeting the challenges posed by the ILC requirements will be discussed.
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THPMS011 | Design Considerations and Modeling Results for ILC Damping Ring Wigglers Based on the CESR-c Superconducting Wiggler | wiggler, damping, electron, collider | 3014 | |||||
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Funding: Funding provided by NSF grant PHY-0202078 |
The ILC damping rings require wiggler magnets with large physical aperture and with excellent field quality to maintain the dynamic aperture of the rings. We consider two possible designs derived from the wigglers presently in operation at the Cornell Electron Storage Ring. Design optimization has been performed based on detailed tracking calculations of dynamic aperture and tune footprint in a full model of the damping ring. Results of finite-element modeling, transfer functions, and the accuracy of analytic models of the wiggler field will be discussed. |
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THPMS013 | Comparison of Tracking Codes for the International Linear Collider | emittance, simulation, linac, lattice | 3020 | |||||
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Funding: Supported by the US Department of Energy, the US National Science Foundation and the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area". |
In an effort to compare beam dynamics and create a benchmark'' for Dispersion Free Steering (DFS) a comparison was made between different International Linear Collider (ILC) simulation programs while performing DFS. This study consisted of three parts. First, a simple betatron oscillation was tracked through each code. Secondly, a set of component misalignments and corrector settings generated from one program was read into the other to confirm similar emittance dilution. Thirdly, given the same set of component misalignments DFS was performed independently in each program and the resulting emittance dilution was compared. Performance was found to agree exceptionally well in all three studies. |
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THPMS038 | Magnetic Measurements and Simulations of a 4-Magnet Dipole Chicane for the International Linear Collider | dipole, simulation, monitoring, collider | 3085 | |||||
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T-474 at SLAC is a prototype BPM-based energy spectrometer for the ILC. We describe magnetic measurements and simulations for the 4-magnet chicane used in T-474. The ILC physics program requires better than 100 part-per-million (ppm) accuracy for energy measurements, which necessitates better than 50 ppm accuracy for magnetic field integral measurements. A 4-dipole chicane is used in T-474 with mid-chicane dispersion of 5-mm and magnetic fields of ~1 kGauss; similar to the current ILC parameters. Stability, reproducibility and consistency of magnetic measurements, including magnetic field maps for the T-474 dipole magnets, are presented using a moving wire, rotating coil, NMR probe, Hall probe and low-field fluxgate magnetometer. Measurements from SLAC's Magnet Test Lab facility as well as in situ measurements in End Station A (ESA) are presented, including measurements of residual magnetic fields in the T-474 chicane between the chicane magnets. Results are provided for an operational mode with a 1-hour calibration cycle, where the chicane magnets are operated in both polarities and at near-zero field.
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THPMS041 | Disruption of Particle Detector Electronics by Beam Generated EMI | radiation, collider, electron, factory | 3094 | |||||
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The possibility that beam generated electromagnetic interference (EMI) could disrupt the operation of particle detector electronics has been of some concern since the inception of short pulse electron colliders more than 30 years ago, Some instances have been reported where this may have occurred but convincing evidence has not been available. This possibility is of concern for the ILC. We have conducted test beam studies demonstrating that electronics disruption does occur using the vertex detector electronics from the SLD detector which ran at the SLC at SLAC. We present the results of those tests and we describe the need for EMI standards, for beam and detector instrumentation, at the ILC.
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THPAS067 | Adaptive Impedance Analysis of Grooved Surface Using the Finite Element Method | impedance, dipole, electromagnetic-fields, controls | 3639 | |||||
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Funding: Work supported by the U. S. Department of Energy under contract DE-AC02-76SF00515 |
Grooved surface is proposed to reduce the secondary emission yield in a dipole and wiggler magnet of International Linear Collider. An analysis of the impedance of the grooved surface based on adaptive finite element is presented in this paper. The performance of the adaptive algorithms, based on an element-element h-refinement technique, is assessed. The features of the refinement indictors, adaptation criteria and error estimation parameters are discussed. |
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FROAC06 | Survey of LLRF Development for the ILC | controls, klystron, feedback, linac | 3810 | |||||
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Funding: FRA |
The key to a successful LLRF design for the International Linear Collider (ILC) relies on a combined effort from the different laboratories involved in this global project. This paper covers the ILC LLRF design progress both long term and for current test facilities around the world. Much of the focus is towards the ILC Test Area and on inter-laboratories collaborations. The SIMCON controller board, originally developed at DESY has been successfully used at FNAL to control the superconducting capture cavity I and II. A joined effort is also underway to modify its hardware to improve its noise performance and upgrading the firmware to achieve a higher intermediate frequency operation. In parallel, several simulation models (U-Penn, FNAL) have been developed in addition to the Simulink based model from DESY. The motivation is to investigate such issues as variable gradients, low beam conditions and bunch compression. Finally, an active exchange of knowledge and expertise continues to occur during collaboration meetings and through mutual participation in accelerator tests and commissioning (Dec06/Jan07 at DESY). |
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FRPMN012 | Bias on Absolute Luminosity Measurements at the ILC from Beam-Beam Space Charge Effects | luminosity, scattering, space-charge, simulation | 3907 | |||||
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A way to determine luminosity at the International Linear Collider (ILC) is to measure the Bhabha event rate in a finely segmented calorimeter (LumiCal) at very low polar angles in the very forward region of the detector. An absolute precision between 10-4 and 10-3 is needed for a number of key physics measurements. Besides theoretical uncertainties on the Bhabha cross section and experimental errors when identifying Bhabha events in the LumiCal, the very strong beam-beam space charge effects which characterise the ILC e+e- collisions lead to a major bias in the counting rate, which drastically limits the luminosity measurement if uncorrected. In this paper, Bhabha event samples produced with the BHLUMI generator are used in the context of the GUINEA-PIG beam-beam simulation to study how beamstrahlung radiation and electromagnetic deflections affect the proposed experimental selections. A corrective method based on determining the luminosity spectrum within the LumiCal is suggested to minimise the resulting errors. The expected residual uncertainty after correction is estimated based on simulations with realistic beam conditions.
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FRPMN090 | A Prototype Energy Spectrometer for the ILC at End Station A in SLAC | dipole, linac, feedback, collider | 4285 | |||||
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The main physics programme of the international linear collider requires a measurement of the beam energy with a relative precision on the order of 10-4 or better. To achieve this goal a magnetic spectrometer using high resolution beam position monitors (BPM) has been proposed. A prototype spectrometer chicane using 4 dipole magnets is currently under development at the End Station A in SLAC, intending to demonstrate the required stability of this method and investigate possible systematic effects and operational issues. This contribution reports on the successful commissioning of the beam position monitor system and the resolution and stability achieved. Also, the initial results from a run with a full spectrometer chicane are presented.
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