| Paper |
Title |
Page |
| MOPC065 |
Wake Field Simulations for Structures of the PITZ RF Photoinjector: Emittance growth estimations
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217 |
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- E. Arevalo, W. Ackermann, E. Gjonaj, W. F.O. Müller, S. Schnepp, T. Weiland
TEMF, Darmstadt
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One of the main concerns in the design of electron guns is the generation of low-emittance beams. One source of emittance growth is the beam-surrounding effect, which can be estimated from the wake potentials along the beam path. For the calculation of these potentials an accurate knowledge of the short range wake fields induced in the different parts of the gun with geometrical discontinuities is necessary. The computation of these wake fields is a challenging problem, as an accurate resolution for both the small bunch and the large model geometry is needed. Here with the help of numerical wake-potential calculations we analytically estimate the emittance growth for the RF electron gun of the Photoninjector Test Facility at DESY Zeuthen (PITZ).
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| MOPP013 |
Coupler Kick for Very Short Bunches and its Compensation
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580 |
| |
- M. Dohlus, I. Zagorodnov
DESY, Hamburg
- E. Gjonaj, T. Weiland
TEMF, Darmstadt
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In this contribution we estimate two different effects: the kick due to asymmetry of the external accelerating field (coupler RF kick) and the kick due to electromagnetic field of the bunch scattered by the couplers (coupler wake kick). We take into acoount the cavities and calculate the periodic solution for bunch with an rms width of 300 mkm. The different possibilities for compensation of the kick are considered.
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| TUPP019 |
Wakefield and RF Kicks due to Coupler Asymmetry in TESLA-type Accelerating Cavities
|
1571 |
| |
- K. L.F. Bane, C. Adolphsen, Z. Li
SLAC, Menlo Park, California
- M. Dohlus, I. Zagorodnov
DESY, Hamburg
- E. Gjonaj, T. Weiland
TEMF, Darmstadt
- I. G. Gonin, A. Lunin, N. Solyak, V. P. Yakovlev
Fermilab, Batavia, Illinois
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In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate asymmetries in the fields that will kick the beam and tend to degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental and higher mode couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetries in) the fundamental RF fields and the other, due to transverse wakefields that are generated even when the beam is on axis. For the ILC configuration we numerically and analytically study both types of kicks and their effect on beam emittance. For the wakefield effect this is quite challenging since the bunches are very short (rms length of 300 microns), the cavity is very long (~1 m), and the distance to steady-state is even longer (~6 m). Finally, we study changes in the coupler design that can greatly reduce the effect.
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| TUPP034 |
Transverse Effects due to Vacuum Mirror of RF Gun
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1613 |
| |
- I. Zagorodnov, M. Dohlus, M. Krasilnikov
DESY, Hamburg
- E. Gjonaj, S. Schnepp
TEMF, Darmstadt
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The transverse kick due to the vacuum mirror in the RF gun can negatively affect the beam emittance. In this contribution we estimate numerically and analytically the transverse wake function of European XFEL RF gun and apply it in beam dynamics studies of the transverse phase space.
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| TUPP095 |
Computation of Resistive Wall Wakefields with the PBCI Code
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1753 |
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- T. Lau, E. Gjonaj, T. Weiland
TEMF, Darmstadt
- R. Maekinen
TUT, Tampere
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Both geometric disturbances and resistive wall loss of accelerator cavities contribute to the impedance causing the beam to lose energy. Impedance due to arbitrary three-dimensional (3-D) geometries can be computed with the Parallel Beam Cavity Interaction (PBCI), a parallelized, 3D-wakefield code. However, the contribution of wall loss is often significant. The contribution of this work is to incorporate resistive wall loss into 3-D time-domain simulation. Surface-impedance concept is used to consider wide-band skin-effect loss of metal. In theory, the proposed approach can be extended to consider high-frequency phenomena such as frequency-dependent conductivity of metal and anomalous skin effect.
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