| Paper |
Title |
Page |
| WEPLT062 |
Wakefield Calculations for TTF-II
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1984 |
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- I. Zagorodnov, T. Weiland
TEMF, Darmstadt
- M. Dohlus
DESY, Hamburg
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In this paper we estimate long- and short-range wake functions for new elements to be used in TESLA Test Facility (TTF) - II. The wake potentials of the LOLA-IV structure and the 3rd harmonic section are calculated numerically for very short bunches and analytical approximations for wake functions in short and long ranges are obtained by fitting procedures based on analytical estimations. The numerical results are obtained with code ECHO for high relativistic Gaussian bunches with RMS deviation up to 0.015 mm. The calculations are carried out for the complete structures (including bellows, rounding of the irises and the different end cell geometries) supplied with ingoing and outgoing pipes. The low frequency spectra of the wake potentials is calculated using the Prony-Pisarenko method.
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| THPLT036 |
New Discretization Scheme for Wake Field Computation in Cylindrically Symmetric Structures
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2556 |
| |
- R. Hampel, T. Weiland, I. Zagorodnov
TEMF, Darmstadt
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Collective effects due to wake fields are a limiting factor in almost every new front line accelerator. Since the early 80's computer codes such as TBCI and MAFIA have been developed for computing wake fields in realistic accelerator structures. With the advent of linear collider studies and small wavelength FEL projects these codes had to face a severe limitation. For the very short bunches in these new accelerators combined with the need for an analysis of very long sections the discrete dispersion became a serious drawback. This effect of having only discrete field values rather than continous ones can be overcome by special algorithms such as semi-implicit integrators as used e.g. in the wake field code ECHO. In this paper we present a new explicit approach which combines the advantage of explicit algorithms (fast) with the absence of dispersion in beam direction.
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| THPLT077 |
MPI Parallel Computation of Wake Fields by Using Time Domain Boundary Element Method
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2670 |
| |
- K. Fujita, H. Kawaguchi
Muroran Institute of Technology, Department of Electrical and Electronic Engineering, Muroran
- T. Weiland, I. Zagorodnov
TEMF, Darmstadt
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This paper presents wake field and wake potential calculation by using the Time Domain Boundary Element Method (TDBEM) on the MPI parallel computation system. The TDBEM is based on the electric field integral equation (EFIE) and the electric field integral equation (MFIE) in time domain. In wake field simulation, an important advantage of these equations is that electromagnetic fields in an accelerator cavity are explicitly expressed as a sum of charged particle self-fields and wake fields in time domain. On the other hand, the TDBEM has serious difficulties in practical numerical simulation, such as numerical instabilities, huge memory requirements, and heavy calculation cost. However, recent remarkable progress of computer performance makes the TDBEM possible to be used in practical simulations. According to these backgrounds, we apply the TDBEM to wake field simulation in the MPI parallel computer system. Simulation results are compared with that of a conventional method, the Finite Integration Techniques (FIT), and good agreements are shown.
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