| Paper |
Title |
Page |
| MOPP034 |
Large Scale Linac Simulations Using a Globalised Scattering Matrix Approach
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619 |
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- I. R.R. Shinton, R. M. Jones
UMAN, Manchester
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A globalised cascaded scattering matrix scheme serves as practical method to simulate the electromagnetic (e.m.) fields in the groups of cavities which constitute the main accelerating structures of a linac. The cascaded scattering matrix technique is a well-proven method which allows realistic fabrication errors to be incorporated in an efficient manner without the necessity to re-mesh the entire geometry. Once the unit cell structures have been determined using a numerical scheme, such as finite element method utilized here, the overall cascaded scattering matrix calculation requires little in the way of computational resources or time and is consequently an efficient means of characterizing the e.m. field. Details of the e.m. field, shunt impedance and trapped modes for large scale linac simulations applied to the baseline and alternate high gradient cavities for the ILC and applications to XFEL are presented.
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| WEPP085 |
RF Coupler Kicks and Wake-fields in SC Accelerating Cavities
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2719 |
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- N. Juntong, R. M. Jones, I. R.R. Shinton
UMAN, Manchester
- C. D. Beard
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
- G. Burt
Cockcroft Institute, Warrington, Cheshire
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The main accelerating cavities of the ILC provide acceleration of both positron and electron beams to 250 GeV per beam and 500 GeV per beam in a proposed upgrade. The wake-field excited by each ultra-relativistic beam in the accelerating cavities can seriously dilute the emittance of the particles within the beams. Each cavity is supplied with both fundamental and higher order mode couplers. The geometrical configuration of these RF couplers results in an asymmetrical field and this gives rise to both an RF kick being applied to the beam and transverse wake-field. Detailed e.m. fields are simulated in the vicinity of the couplers in order to assess the impact on the beam dynamics. We investigate modified geometries with a view to alleviating the emittance dilution resulting from the e.m. field associated with the RF couplers.
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