CERN, Geneva
NSRRC, Hsinchu
LANL, Los Alamos, New Mexico
Dose rate modeling and post irradiation measurements of the Isotope Production Facility beamline, at the Los Alamos Neutron Science Center (LANSCE) accelerator, have determined that a radiation shielding shutter is required to protect personnel from shine from irradiated targets for routine beam tunnel entries. This paper will describe radiation dose modeling, shielding calculations and the failsafe mechanical shutter design.
3D computing simulations have been performed to study the magnetic field distribution of the SNS ring extraction Lambertson septum magnet. The magnetic field for extracted beams is fully characterized in all the aspects. The stray field on the circulating beam line and the effect of a shielding box up-stream and a shielding cap down-stream is investigated. In addition, the magnetic interference between the Lambertson and an adjacent quadrupole has been studied. The simulations have provided valuable information for the SNS ring commissioning and operation. This paper reports our simulation techniques and the major results.
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.
UNM, Albuquerque, New Mexico
LBNL, Berkeley, California
SLAC, Menlo Park, California
We discuss our progress on integration of the coupled Vlasov-Maxwell equations in 4D. We emphasize Coherent Synchrotron Radiation from particle bunches moving on arbitrary curved planar orbits, with shielding from the vacuum chamber, but also include space charge forces. Our approach provides simulations with lower numerical noise than the macroparticle method, and will allow the study of emittance degradation and microbunching in bunch compressors. The 4D phase space density (PSD) is calculated in the beam frame with the method of local characteristics (PF). The excited fields are computed in the lab frame from a new double integral formula. Central issues are a fast evaluation of the fields and a deep understanding of the support of the 4D PSD. As intermediate steps, we have (1) developed a parallel self-consistent code using particles, where an important issue is the support of the charge density*; (2) studied carefully a 2D phase space Vlasov analogue; and (3) derived an improved expression of the field of a 1D charge/current distribution which accounts for the interference of different bends and other effects usually neglected**. Results for bunch compressors are presented.
* Self Consistent Particle Method to Study CSR Effects in Bunch Compressors, Bassi, et.al., this conference.** CSR from a 1-D Bunch on an Arbitrary Planar Orbit, Warnock, this conference.
* M. Borland, APS Report LS-287
BNL, Upton, Long Island, New York
JINR, Dubna, Moscow Region
IBA, Louvain-la-Neuve
LLNL, Livermore, California
NSCL, East Lansing, Michigan
ORNL, Oak Ridge, Tennessee
LANL, Los Alamos, New Mexico
ANL, Argonne, Illinois
High-power tests were conducted on a 350MHz, single-cell copper accelerating cavity driven simultaneously by two H-loop input couplers for the purpose of determining the reliability, performance, and power-handling capability of the cavity and related components, which have routinely operated at 100kW power levels. The test was carried out utilizing the APS 350MHz RF Test Stand, which was modified to split the input rf power into two 1/2-power feeds, each supplying power to a separate H-loop coupler on the cavity. Electromagnetic simulations of the two-coupler feed system were used to determine coupler match, peak cavity fields, and the effect of phasing errors between the coupler feedlines. The test was conducted up to a maximum total rf input power to the cavity of 200kW CW. Test apparatus details and performance data will be presented.
Fermilab, Batavia, Illinois
Fermilab, Batavia, Illinois
As part of a program to improve cavity performance reproducibility for the ILC, Fermilab is developing a facility for vertical testing of SRF cavities. It operates at a nominal temperature of 2K, using an existing cryoplant that can supply LHe in excess of 20g/sec and provides steady-state bath pumping capacity of 125W at 2K. The below-grade cryostat consists of a 4.9m long vacuum vessel and 4.5m long LHe vessel. The cryostat is equipped with external and internal magnetic shielding to reduce the ambient magnetic field to <10mG. Internal fixed and external movable radiation shielding ensures that radiation levels from heavily field-emitting cavities remain low. In the event that radiation levels exceed allowable limits, an integrated personnel safety system consisting of RF switches, interlocks, and area radiation monitors disables RF power to the cavity. In anticipation of increased throughput requirements that may be met with additional test stand installations, sub-systems have been designed to be easily upgradeable or to already meet these anticipated needs. Detailed facility designs, performance during system commissioning, and results from initial cavity tests are presented.
Jefferson Lab, Newport News, Virginia
Fermilab, Batavia, Illinois
Fermilab is developing a facility for vertical testing of SRF cavities as part of a program to improve cavity performance reproducibility for the ILC. The RF system for this facility, using the classic combination of oscillator, phase detector/mixer, and loop amplifier to detect the resonant cavity frequency and lock onto the cavity, is based on the proven production cavity test systems used at Jefferson Lab for CEBAF and SNS cavity testing. The design approach is modular in nature, using commercial-off-the-shelf (COTS) components. This yields a system that can be easily debugged and modified, and with ready availability of spares. Data acquisition and control is provided by a PXI-based hardware platform in conjunction with software developed in the LabView programming environment. This software provides for amplitude and phase adjustment of incident RF power, and measures all relevant cavity power levels, cavity thermal environment parameters, as well as field emission-produced radiation. It also calculates the various cavity performance parameters and their associated errors. Performance during system commissioning and initial cavity tests will be presented.
Yale University, Physics Department, New Haven, CT
Columbia University, New York
IAP/RAS, Nizhny Novgorod
Omega-P, Inc., New Haven, Connecticut
Development of a future multi-TeV warm collider demands new technological solutions and new accelerator structure materials. The Ka-Band test facility being put into operation at Yale University that centers on the Yale/Omega-P 34-GHz magnicon allows users to carry out high gradient experiments on RF breakdown, pulse fatigue, tests of new high power pulse manipulation systems, and RF components. The magnicon is now conditioned for a pulse width up to 1 μs, at an output power level high enough for basic studies of electric and magnetic RF field limits at surfaces of conductors and dielectrics. The high-power waveguide transmission system for the facility is assembled and ready for tests. It includes RF windows, phase shifters, 13 mm diameter TE 11 waveguides, mode converters, etc. Recently the assembled system has undergone conditioning in preparation for carrying out first "user" experiments.
Fermilab, Batavia, Illinois
ANL, Argonne, Illinois
Euclid TechLabs, LLC, Solon, Ohio
LET
SLAC, Menlo Park, California
A joint project is underway by the Naval Research Laboratory (NRL) and Argonne National Laboratory (ANL), in collaboration with the Stanford Linear Accelerator Center (SLAC), to develop a compact X-band accelerator for testing dielectric-loaded accelerator (DLA) structures.* The accelerator will use a 5-MeV injector previously developed by the Tsinghua University in Beijing, China, and will accommodate test structures up to 0.5 m in length. Both the injector and the structures will be powered by an 11.4-GHz magnicon amplifier that can produce 25 MW, 200-ns output pulses at up to 10 Hz. The injector will require ~5 MW of rf power, leaving ~20 MW to power the test structures. This paper will present a progress report on the construction and commissioning of the test accelerator, which will be located in a concrete bunker in the Magnicon Facility at NRL.
* S. H. Gold et al., Proc. PAC 2005.
UNM, Albuquerque, New Mexico
SLAC, Menlo Park, California
We report on the implementation of a self consistent particle code to study CSR effects on particle bunches traveling on arbitrary planar orbits. Shielding effects are modeled with parallel perfectly conducting plates. The "vertical" charge distribution is assumed to be stationary. The macroscopic Maxwell equations are solved in the lab frame while the equations of motion are integrated in the beam frame interaction picture where the dynamics is governed by the self fields alone. We study different methods to construct a smooth charge density from particles, e.g. gridless nonparametric curve estimation and charge deposition plus filtering. We present numerical results for bunch compressors. In particular, we study different initial distributions. The transverse initial distribution is Gaussian and we study different initial longitudinal distributions: Gaussian, parabolic and nonlinear chirp. A parallel version of the code has been implemented and this will speed up parameter analysis and allow micro-bunching studies.