| Paper | Title | Other Keywords | Page | ||
|---|---|---|---|---|---|
| MOPP128 | Comparison of Stretched-wire, Bead-pull and Numerical Impedance Calculations on 3.9 GHz Dipole Cavities | dipole, impedance, simulation, radio-frequency | 859 | ||
|
In order to verify detailed impedance and wakefield simulations, the resonant modes in an aluminium model of the 9-cell ILC crab cavity were investigated using a stretched-wire frequency domain measurement, as well as frequency-domain bead-pull measurements. These measurements were compared to numerical simulations in order to verify that the complete cavity mode spectrum could be experimentally characterised for this high frequency structure. The analysis of the results and the accuracy and/or limitations of each method is presented.
|
|
|
||
| TUPP047 | Simulation Studies on Coupler Wakefield and RF Kicks for the International Linear Collider with MERLIN | linac, emittance, simulation, linear-collider | 1649 | ||
|
One of the critical issues in the design of the superconducting cavities or the International Linear Collider (ILC) is the influence of the RF and higher order mode (HOM) couplers on the beam dynamics. Both types of couplers break the rotational symmetry of the cavity and introduce non vanishing transverse wakefields even on the cavity axis. Furthermore the RF input coupler introduces an asymmetry into the accelerating RF field and thereby additional transverse field components. We have implemented both effects following the calculations presented previously* into the MERLIN C++ library**. This allows us to study the influence of wakefield and RF kicks on the beam dynamics, the bunch shape and the overall performance of the ILC for different proposed coupler designs.
|
*I. Zagorodnov and M. Dohlus, ILC Workshop, DESY 2007; K. Bane and I. Zagorodnov, Wake Fest 07, SLAC 2007. |
|
||
| WEPP081 | Wake-fields and Beam Dynamics Simulations for ILC ACD Accelerating Cavities | emittance, damping, linac, simulation | 2707 | ||
|
The ILC aims at colliding bunches of electrons and positrons at a centre of mass energy of 0.5 TeV and in a proposed upgrade to 1 TeV. These bunches of charged particle are accelerated in superconducting linacs. The baseline design for the ILC relies on the relatively mature TESLA-style cavities, with a proposed gradient of more than 30 MV/m and is known as the baseline configuration document (BCD). However, here we investigate electromagnetic fields in superconducting cavities, with the potential to reach accelerating gradients in excess of 50 MV/m, and these are the subject of the alternative configuration document (ACD). We analyse the band structure and necessary damping requirement of the wake-fields in two design configurations: Cornell's re-entrant cavity and KEK's Ichiro cavity. The emittance dilution arising from beams subjected to injection offsets and from cavity misalignments are studied in beam dynamics simulations.
|
|
|
||
| WEPP085 | RF Coupler Kicks and Wake-fields in SC Accelerating Cavities | simulation, dipole, linac, coupling | 2719 | ||
|
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.
|
|
|