| Paper | Title | Page |
|---|---|---|
| TUPMS092 | GdfidL Simulations of Non-Linear Tapers for ILC Collimators | 1380 |
|
||
| This paper summarises the GdfidL simulations relating to non-linear collimators, which offer the potential for improved wakefield performance at the ILC. Such collimators provide a further method for understanding the performance of simulation software in this challenging regime. Our results are compared with data from ESA at SLAC. | ||
| TUPMS093 | Computations of Wakefields in the ILC Collimators | 1383 |
|
||
|
The collimators in the ILC serve the dual purpose of reducing the beam halo and as of a form of machine protection from potentially miss-steered beams. However, there is a significant wakefield in the immediate vicinity of the beam caused by their presence. It is important to be able to predict this short-range wakefield and the extent which it dilutes the emittance of the beam. We extend the previous analysis*, ** of wake-fields in collimators to realistic short bunches applicable to the ILC. We achieve these results using the finite difference code GdfidL. The angular wake is decomposed into its constituent components for rectangular collimators and compared with their circular collimator counterparts. Comparisons are made between these simulations, existing analytical models, and experimental results.
* C. Beard and R. M. Jones, EUROTeV-Report-2006-103** C. Beard and J. Smith, EPAC06 Proc. MOPLS070 |
||
| FRPMS074 | Measurements of the Transverse Collimator Wakefields due to Varying Collimator Characteristics | 4207 |
|
||
|
Funding: EUROtev Contract #011899RIDS US DOE Contract DEAC02-76SF00515
We report on measurements of the transverse wakefields induced by collimators of differing characteristics. An apparatus allowing the insertion of different collimator jaws into the path of a beam was installed in End Station A (ESA) in SLAC. Eight comparable collimator geometries were designed, including one that would allow easy comparison with previous results, and were installed in this apparatus. Measurements of the beam kick due to the collimator wakefields were made with a beam energy of 28.5 GeV, and beam dimensions of ~100 microns vertically and a range of 0.5 to 1.5 mm longitudinally. The trajectory of the beam upstream and downstream of the collimator test apparatus was determined from the outputs of ten BPMs (four upstream and six downstream), thus allowing a measurement of the angular kick imparted to the beam by the collimator under test. The transverse wakefield was inferred from the measured kick. The different aperture designs, data collection and analysis, and initial comparison to theoretical and analytic predictions are presented here.
* "An Apparatus for the Direct Measurement of Collimator Transverse Wakefields", P. Tenenbaum, PAC '99** "Direct Measurement of the Resistive Wakefield in Tapered Collimators", P Tenenbaum, PAC '04 |
||
| THPAN068 | Wakefield Models for Particle Tracking Codes | 3378 |
|
||
| Wakefields have a considerable effect on beam dynamics and they must not be neglected for emittance growth studies, background estimates and other problems. The codes used for these problems are normally not capable of self-consistent wakefield calculations. They should thus be extended with either analytical models or export the wakefields numerically evaluated with other codes (such as Gdfidl) when analytical models are not feasible. We discuss both approaches and present their implementation in PLACET, MERLIN and BDSIM. The simulation results for the ILC and CLIC beam delivery systems are given as an example. Results produced with different codes are compared. |