Transverse Wakefield Analysis for the Nlc & Jlc Detuned Structures on a Parallel Computer ∗

The detuned structure (DS) has been proposed as one possible design to control the emittance growth of long bunch trains in linear colliders due to transverse wakefields. A DS typically consists of over a hundred cells with tapering from cell to cell of the order of few microns to decohere the dipole modes. The design parameters are targeted for two orders of magnitude reduction in the wakefield experienced by the trailing bunch. Field analysis of such a large heterogeneous structure is impractical with finite-difference schemes using structured grids. This paper presents the results from calculations performed on a parallel computer using a finite-element code based on an unstructured grid. We discuss the parallel implementation issues and show comparisons between simulation results and the wakefield data taken on both the NLC and JLC detuned structures.