Paper  Title  Page 

WEPMN077  Impedance Measurements on a Test Bench Model of the ILC Crab Cavity  2206 


Funding: This work was supported by the EC under the FP6 'Research Infrastructure Action  Structuring the European Research Area' EUROTeV DS Project Contract no.011899, RIDS and PPARC. In order to verify detailed impedance simulations, the modes in an aluminium model of the ILC crab cavity were investigated using a beadpulling technique as well as a stretchedwire frequency domain measurement. The combination of these techniques allow for a comprehensive study of the modes of interest. For the wire measurement, a transverse alignment system was fabricated and rf components were carefully designed to minimize any potential impedance mismatches. The measurements are compared with direct simulations of the stretchedwire experiments using numerical electromagnetic field codes. High impedance modes of particular relevance to the ILC crab cavity are identified and characterized 

WEPMN079  Power Coupler for the ILC Crab Cavity  2212 


Funding: This work was supported by the EC under the FP6 "Research Infrasctructure Action  Structuring the European Research Area" EUROTeV DS Project Contract no.011899 RIDS and PPARC. The ILC crab cavity will require the design of an appropriate power coupler. The beamloading in dipole cavities is considerably more variable than accelerating cavities, hence simulations have been performed to establish the required external Q. Simulations of a suitable coupler were then performed and were verified using a normal conducting prototype with variable coupler tips. 

WEPMN080  Development of Circuits and System Models for the Synchronization of the ILC Crab Cavities  2215 


Funding: The Commission of the European Communities under the 6th Framework Programme (Structuring the European Research Area) The UK particle physics and astromony research council. The ILC reference design report (RDR) recommends a 14 mrad crossing angle for the positron and electron beams at the IP. A matched pair of crab cavity systems are required in the beam delivery system to align both bunches at the IP. The use of a multicell, 3.9GHz dipole mode superconducting cavity, derived from the Fermilab CKM cavity. Dipolemode cavities phased for crab rotation are shifted by 90 degrees with respect to similar cavities phased for deflection. Uncorrelated phase errors of 0.086 degrees (equivalent to 61fs) for the two cavity systems, gives an average of 180nm for the relative deflection of the bunch centers. For a horizontal bunch size of 655nm, a deflection of 180nm reduces the ILC luminosity by 2%. The crab cavity systems are to be placed ~28m apart and their synchronization to within 61fs is on the limit of what is presently achievable. This paper describes the design and testing of circuits and control algorithms under development at the Cockcroft Institute in the UK for proof of principle experiments planned on the ERLP at Daresbury and on the ILCTA test beamline at FNAL. Simulation results for measurement and control systems are also given. 

WEPMS050  HOM and LOM Coupler Optimizations for the ILC Crab Cavity  2457 


Funding: Work supported by DOE contract DEAC0276SF00515 The FNAL 9cell 3.9GHz deflecting cavity designed for the CKM experiment was chosen as the baseline design for the ILC BDS crab cavity. Effective damping is required for the lowerorder TM01 modes (LOM), the sameorder TM11 modes (SOM) as well as the HOM modes to minimize the beam loading and beam centroid steering due to wakefields. Simulation results of the original CKM design using the eigensolver Omega3P showed that both the notch filters of the HOM/LOM couplers are very sensitive to the notch gap, and the damping of the unwanted modes is suboptimal for the ILC. To meet the ILC requirements, the couplers were redesigned to improve the damping and tuning sensitivity. With the new design, the damping of the LOM/SOM/HOM modes is significantly improved, the sensitivity of the notch filter for the HOM coupler is reduced by one order of magnitude and appears mechanically feasible, and the LOM coupler is simplified by aligning it on the same plane as the SOM coupler and by eliminating the notch filter. In this paper, we will present the coupler optimization and tolerance studies for the crab cavity. 

WEOCAB01  Design of the Beam Delivery System for the International Linear Collider  1985 


The beam delivery system for the linear collider focuses beams to nanometer sizes at the interaction point, collimates the beam halo to provide acceptable background in the detector and has a provision for stateofthe art beam instrumentation in order to reach the physics goals. The beam delivery system of the International Linear Collider has undergone several configuration changes recently. This paper describes the design details and status of the baseline configuration considered for the reference design.  
Slides  
FRPMS069  Simulations of Stretched Wire Measurements of 3.9GHz Cavities for the ILC  4177 


We present wakefield simulations on both the main superconducting cavities and on the beam delivery system crab cavities of the ILC. We utilize both finite difference and finite element computer codes to simulate the electromagnetic fields in these cavities in the presence of a stretched wire. This study is intended to both predict the wakefield in experiments on the modal characterisation of 3.9 GHz cavities in progress at the Cockcroft Institute and, to explore practical issues concerning the feasibility of using this stretched wire method to investigate modes in the ILC main cavities. Multicell scattering matrices and the modes in infinite periodic structures are calculated with a view to aiding the interpretation of experimental results. A modal convergence study is also included 