Paper  Title  Page 

MOOBB03  An Alternative 1D Model for CSR with Chamber Shielding  52 


An alternative 1D model for modeling the longitudinal coherent synchrotron radiation (CSR) impedance is proposed. The code CSRZ* is used to calculate the CSR impedance with rectangular chamber shielding. Along the beam orbit, which may be formed by multi bends interleaved with drifts, the vacuum chamber is sliced into a series of segments. The lowfrequency CSR impedance for each segment, in this case chamber shielding is significant, is obtained by numerical calculations. The highfrequency CSR impedance, in this case chamber shielding is negligible, is estimated by an analytical model**. The wake kick at each segment is computed via inverse Fourier transform of the impedance convolved the the beam spectrum. The most attractive merit of the method for CSR modeling lies in taking into account the realistic chamber shielding.
* D. Zhou, et al., To be published in Jpn. J. Appl. Phys. ** M. Borland, Phys. Rev. ST Accel. Beams 4, 070701 (2001). 

Slides MOOBB03 [1.856 MB]  
WEPPR054  Calculation of Coherent Wiggler Radiation using Eigenfunction Expansion Method  3048 


An analytic method originated by Y. H. Chin* was extended to calculate the electromagnetic fields and the longitudinal impedance due to coherent wiggler radiation (CWR) in a rectangular chamber. The method used dyadic Green functions based on eigenfunction expansion method in electromagnetic theory and was rigorous for the case of straight chamber. We rederived the theory and did find the full expressions for the longitudinal impedance of a wiggler with finite length. With shielding of chamber, the CWR impedance indicated resonant properties which were not seen in the theory for CWR in free space.
* Y.H. Chin, LBL29981, 1990. 
