| Title |
Geometric Beam Coupling Impedance of LHC Secondary Collimators |
| Authors |
- O. Frasciello, S. Tomassini, M. Zobov
INFN/LNF, Frascati (Roma), Italy
- A. Grudiev, N. Mounet, B. Salvant
CERN, Geneva, Switzerland
|
| Abstract |
The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep under control beam instabilities and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are the main impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were by about a factor of 2 higher with respect to the theoretical predictions based on the current model. Up to now the resistive wall impedance has been considered as the major impedance contribution for collimators. By carefully simulating their geometric impedance we show that for the graphite collimators with half-gaps higher than 10 mm the geometric impedance exceeds the resistive wall one. In turn, for the tungsten collimators the geometric impedance dominates for all used gap values. Hence, including the geometric collimator impedance into the LHC impedance model enabled us to reach a better agreement between the measured and simulated collimator tune shifts.
|
| Funding |
Work supported by European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404 |
| Paper |
download TUPRI049.PDF [1.098 MB / 3 pages] |
| Export |
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| Conference |
IPAC2014, Dresden, Germany |
| Series |
International Particle Accelerator Conference (5th) |
| Proceedings |
Link to full IPAC2014 Proccedings |
| Session |
Poster Session, Ribery Area |
| Date |
17-Jun-14 16:00–18:00 |
| Main Classification |
05 Beam Dynamics and Electromagnetic Fields |
| Sub Classification |
D05 Instabilities - Processes, Impedances, Countermeasures |
| Keywords |
impedance, factory, simulation, HOM, wakefield |
| Publisher |
JACoW Publishing, Geneva, Switzerland |
| Editors |
Christine Petit-Jean-Genaz (CERN, Geneva, Switzerland); Gianluigi Arduini (CERN, Geneva, Switzerland); Peter Michel (HZDR, Dresden, Germany); Volker RW Schaa (GSI, Darmstadt, Germany) |
| ISBN |
978-3-95450-132-8 |
| Published |
July 2014 |
| Copyright |
|
