UMD, College Park, Maryland
Transfer maps for magnetic elements in storage and damping rings can depend sensitively on nonlinear fringe-field and high-order-multipole effects. The inclusion of these effects requires a detailed and realistic model of the interior and fringe magnetic fields, including their high spatial derivatives. A collection of surface fitting methods has been developed for extracting this information accurately from 3-dimensional magnetic field data on a grid, as provided by various 3-dimensional finite element field codes. The virtue of surface methods is that they exactly satisfy the Maxwell equations and are relatively insensitive to numerical noise in the data. These techniques can be used to compute, in Lie-algebraic form, realistic transfer maps for the proposed ILC Damping Ring wigglers. An exactly-soluble but numerically challenging model field is used to provide a rigorous collection of performance benchmarks.
ANL, Argonne
MSU, East Lansing, Michigan
Many processes in Physics can be described by Partial Differential equations (PDE’s). For various practical problems, very precise and verified solutions of PDE are required; but with conventional finite element or finite difference codes this is difficult to achieve because of the need for an exceedingly fine mesh which leads to often prohibitive CPU time. We present an alternative approach based on high-order quadrature and a high-order finite element method. Both of the ingredients become possible through the use of Differential Algebra techniques. Further the method can be extended to provide rigorous error verification by using the Taylor model techniques. Application of these techniques and the precision that can be achieved will be presented for the case of 3D Laplace’s equation. Using only around 100 finite elements of order 7, verified accuracies in the range of 10-7 can be obtained.
GSI, Darmstadt
ORNL, Oak Ridge, Tennessee
IAP, Frankfurt am Main
CEA, Gif-sur-Yvette
The GSI Univeral Linear Accelerator UNILAC can accelerate all ion species from protons to uranium. Hence its DTL section is equipped with e.m. quadupoles allowing for a wide range of field strength along the section. During the last years various campaigns on the quality of high current beams at the DTL exit as function of the applied transverse focusing have been performed. Measurements were compared with up to four different high intensity beam dynamics codes. Those comparisons triggered significant improvement of the final beam quality. The codes were used to prepare an ambitious and successful beam experiment on the first observation of a space charge driven octupolar resonance in a linear accelerator.
Diamond, Oxfordshire
JAI, Oxford
The Diamond light source started operation for users in January 2007. With the successful commissioning of the nominal optics, delivering a 2.75 nm emittance beam at 3 GeV, we now routinely provide the users with a 250 mA beam with a lifetime of >20 h, exceeding the minimum specified current-lifetime product of 3000 mAh. Driven by the necessity to guarantee a correct implementation of the nonlinear optics, a significant experimental and theoretical effort is ongoing to understand and improve the nonlinear beam dynamics in the storage ring. The necessity to control the nonlinear beam dynamics is even more urgent with the installation of a large number of small gap (5 mm) in-vacuum insertion device and the need to control the injection efficiency with Top-Up operation. We report here the present status of the analysis of the nonlinear beam dynamics and the main experimental results.
LBNL, Berkeley, California
Superconducting magnets for particle accelerators are complex devices requiring the use of sophisticated modeling techniques to predict their performance. A complete description of the magnet behavior can only be obtained through a multi-physics approach which combines magnetic, mechanical, and electrical-thermal models. This approach is essential in particular for the next generation of magnets, which will likely implement strain sensitive conductors like Nb3Sn and will handle forces significantly larger than in the present LHC dipoles. The design of high field superconducting magnets has benefited from the integration between CAD, magnetic, and structural analysis tools allowing a precise reproduction of the magnet 3D geometry and a detailed analysis of the three-dimensional strain in the superconductor. In addition, electrical and thermal models have made possible investigating the quench initiation process and the thermal and stress conditions of the coil during the propagation of a quench. We present in this paper an overview of the integrated design approach and we report on simulation techniques aimed to predict and reproduce magnet behavior from assembly to quench.
BNL, Upton, Long Island, New York
In order to preserve polarization during polarized proton operation for RHIC, two partial Siberian Snakes are employed in the AGS, where a number of strong spin depolarization resonances must be crossed. These Snakes cause a significant distortion to the injection lattice of the AGS and must be included in the on-line model. In this report we discuss the problem of modeling Snakes as optical elements, particularly as madx elements, and present results comparing measurements to the AGS on-line model.
IAP, Frankfurt am Main
For the development of high energy and high duty cycle RFQs accurate particle dynamic simulation tools are important for optimizing designs, especially in high current applications. To describe the external fields in RFQs, the Poisson equation has to be solved taking the boundary conditions into account. In PteqHI this is now done by using a finite difference method on a grid. This method will be described and simulation results will be compared to different RFQ particle dynamic codes.
Northern Illinois University, DeKalb, Illinois
This research involves the development of a model of the small circumference (11.5 m) accelerator in which the earth’s field has a strong effect, and in which image charge forces are also included. The code used for this simulation was COSY Infinity 9.0 which uses differential algebras to determine high order map elements, as well as quantities such as chromaticity. COSY also uses Normal Form algorithms to determine the betatron tune and any amplitude dependent tune shifts which may result. The power of COSY is that it can derive the required quantities directly form the map without costly integration and tracking. Thus determining the map for both the default elements of the ring, plus the effects of image charge forces, and the earth’s magnetic field is both non-trivial, and important. This research uses the Baker Campbell Hausdorf method to determine the map of the ring with the external fields included. Furthermore COSY has the ability to directly implement misalignments within the beamline itself allowing for a study of their effects on beam dynamics. The presentation will include both coding development and applications to the University of Maryland Electron Ring.
Fermilab, Batavia
Similar to many other linear accelerators, the High Intensity Neutron Source requires an RFQ for initial acceleration and formation of the bunched beam structure. The RFQ design includes two main tasks: a) the beam dynamics design resulting in a vane tip modulation table for machining and b) the resonator electromagnetic design resulting in the final dimensions of the resonator. The focus of this paper is on the second task including simulating high power operation of RFQ. We report complete and detailed RF modeling on the HINS RFQ resonator using simulating codes CST Microwave Studio (MWS) and Ansoft High Frequency Structure Simulator (HFSS). All details of the resonator such as input and output radial matchers, the end cut-backs etc have been precisely determined. In the first time a full size RFQ model with modulated vane tips, the power couplers and all tuners installed has been built, and a complete simulation of RFQ tuning has been performed. Finally some aspects of high power operation of RFQ have been investigated. Comparison of the simulation results with experimental measurements demonstrated excellent agreement.