| Paper |
Title |
Other Keywords |
Page |
| MOAPMP01 |
Coupled Transient Thermal and Electromagnetic Finite Element Simulation of Quench in Superconducting Magnets
|
simulation, superconducting-magnet, electromagnetic-fields, controls |
70 |
| |
- C. W. Trowbridge, J. Simkin, S. Taylor, E. Xu
Vector Fields Ltd., Oxford
| |
Resistive, normal zones may propagate through the low temperature superconducting coils. The rise in temperature in the windings and the internal voltages developed during this quench process are a critical issue for magnet safety, in addition the eddy currents induced in support structures during a quench may result in large Lorentz forces that can cause damage. Approximate adiabatic models have been used to achieve good results for the time profile of the current decay*. More accurate methods based on finite element simulations have also been used to obtain temperature and voltage distributions**. This paper describes transient, closely coupled thermal, electromagnetic finite element and circuit simulations developed to model quenching magnets. The program was designed to be efficient for this calculation. It uses nodal finite elements for the transient thermal simulation and edge elements for the electromagnetic simulation. The two simulations can be performed on different symmetry groups so that the model size can be minimized. Circuit models are coupled to the electromagnetic simulator either using filamentary edge loops or with a full volume mesh in the coils. Accurately meshing the coils increases the model size, but it is essential if accurate fields and time derivatives of the field are required. The main source of heat in the coils during quench is resistive loss in the normal zone. However rate dependent losses caused by the changing magnetic field may cause heating and therefore trigger a quench in other coils. Having closely coupled thermal and electromagnetic simulations makes it easy to include these effects and hence greatly improves the reliability of the simulation. Calculated and measured results for a 4 coil superconducting polarized target magnet will be presented. In this system the quench spreads to another coil as a result of rate dependent losses, the calculated results change dramatically if these losses are not included.
* M. N. Wilson, Superconducting magnets p217ff
** S. Caspi et Al, Calculating Quench propagation with Ansys, IEEE Trans. Appl. Supperconduct. Vol 13, No2, pp1714-1717
|
|
|
Slides
|
|
|
|
| TUMPMP03 |
BEAM DYNAMICS STUDIES FOR THE HIGH-ENERGY STORAGE RING
|
electron, luminosity, antiproton, injection |
96 |
| |
- A. Lehrach, B. Lorentz, R. Maier, D. Prasuhn, H. Stockhorst, R. Tölle, D. M. Welsch
FZJ, Jülich
- O. Boine-Frankenheim, R. W. Hasse, S. Sorge
GSI, Darmstadt
- F. Hinterberger
Universität Bonn, Helmholtz-Institut für Strahlen- und Kernphysik, Bonn
| |
Funding: INTAS grant No. 03-54-5584 (Advanced Beam Dynamics for Storage Rings), EU-FP6 FP6 contract No. 515873(DIRAC Secondary-Beams)
The HESR is planned as an antiproton storage ring in the momentum range from 1.5 to 15 GeV/c. An important feature of this new facility is the combination of phase space cooled beams utilizing electron and stochastic cooling and dense internal targets (e.g. pellet targets). In this paper different beam dynamics issues like closed orbit correction, performance of cooled beams interacting with internal targets and luminosity considerations are discussed in respect of utilized simulation codes.
O. Boine-Frankenheim et al., Nucl. Inst. and Meth. A 560, 245 (2006).
A. Lehrach at al., Nucl. Instr. Meth. A 561, 289 (2006).
F. Hinterberger, Jül-Report No. 4206 (2006), ISSN 0944-2952.
|
|
|
|
Slides
|
|
|
|
| TUPPP23 |
Numerical Minimization of Longitudinal Emittance in Linac Structures
|
emittance, controls, linac, acceleration |
124 |
| |
- S. Lange, M. Clemens, L. O. Fichte
Helmut-Schmidt-University, Hamburg
- M. Dohlus, T. Limberg
DESY, Hamburg
| |
Relativistic electron bunches in linear colliders are characterized by 6D phase spaces. In most linear accelerators, the longitudinal phase space distribution does not interact significantly with the transverse distributions. This assumption allows the use of a 2D design model of the longitudinal phase space. The design of linear colliders is typically based on manipulations in the longitudinal phase space. The two dimensional single bunch tracking code LiTrack (Bane/Emma 2005) allows to simulate bunch-compression up to 3rd order and RF acceleration with wake fields. This code is implemented in Matlab with a graphic user interface front end. In order to improve the ability to simulate a two-stage bunch compression system, which consist of a RF accelerating section, a higher harmonic RF section and a dipole magnet chicane, an extension to the LiTrack code is proposed. An analytical model of this two-stage bunch compression system is defined using the energy and the momentum derivatives up to 3rd order of the system. As a consequence, the energy of the system can now be specified directly, for the simulation criteria the peak current and the symmetry of the charge distributions and be specified via parameters. This extended model allows the definition of bunches with an arbitrary energy, phase space correlation, longitudinal emittance, charge distribution and resulting peak current. A minimal longitudinal emittance is generally considered as a quality factor of the bunch, where the bunch energy, peak current and a symmetric charge distribution are represented as constraints. Under these conditions, a constrained optimization problem is defined to minimize the longitudinal emittance with a predetermined bunch-energy and peak-current with respect to the charge distribution symmetry. For the solution of this problem, LiTrack is extended with a optimization solver based on a SQP formulation to find an optimal bunch corresponding to the newly introduced constraints.
|
|
|
|
| WEPPP15 |
Simulations of Pellet Target Effects with Program PETAG01
|
electron, simulation, storage-ring, antiproton |
216 |
| |
- A. Dolinskii, V. Gostishchev, M. Steck
GSI, Darmstadt
- O. A. Bezshyyko
National Taras Shevchenko University of Kyiv, The Faculty of Physics, Kyiv
| |
New internal targets play an important role in modern nuclear and high energy physics research. One of such targets is a pellet target which is a variant of a micro-particle internal target. This target has a number of very attractive features when it used in a storage ring. The software package PETAG01 has been developed for modelling the pellet target and it can be used for numerical calculations of the interaction of a circulating beam with the target in a storage ring. We present numerical calculations to study the beam dynamics of the ions in the storage ring, where strong cooling techniques in combination with the pellet target are applied. Some important effects due to the target in combination with electron cooling and its influence on the beam parameters have been considered.
|
|
|
|
| WEA2IS03 |
The Fermilab Accelerator Control System
|
controls, collider, antiproton, instrumentation |
246 |
| |
- J. F. Patrick
Fermilab, Batavia, Illinois
| |
The Fermilab accelerator complex supports simultaneous operation of 8 and 120 GeV fixed target lines, a high intensity neutrino source (NUMI), antiproton production, and a 1.8 TeV proton-antiproton collider. Controlling all this is a single system known as ACNET. ACNET is based on a three tier architecture featuring a high degree of scalability, large scale parallel data logging, security, accountability, a states facility, a sequencer for automated operation. In recent years the system has been enhanced to support the demands of the current run, and also modified to reduce dependence in the upper layers on the obsolete VAX/VMS platform. A Java based infrastruture has been developed, and is now used for most middle layer functionality as well as some applications. A port of most of the remaining VMS code to Linux is nearing completion. This migration has been accomplished with minimal interruption to operations.
|
|
|
|
Slides
|
|
|
|