# Abstracts

## XX International Linac Conference

## TUA04 (Poster)

**Presenter: **Zenghai Li (SLAC)

** email: **lizh@slac.stanford.edu

**Status: **Complete

**FullText: **
pdf

**Eprint:** physics/0009031
# Design of the JLC/NLC RDDS Structure Using Parallel
Eigensolver Omega3P*

Z. LI, K. KO, R.J. LOEWEN, E.W. LUNDAHL, B. MCCANDLESS, R.H.
MILLER, R.D. RUTH, M.D. STARKEY, Y. SUN, J.W. WANG (SLAC),
T. HIGO (KEK)

The complexity of the Round Damped Detuned Structue (RDDS) for the
JLC/NLC main linac is driven by the considerations of rf efficiency and dipole
wakefield suppression. As a time and cost saving measure for the JLC/NLC, the
dimensions of the 3D RDDS cell are being determined through computer modeling to
within fabrication precision so that no tuning may be needed once the structures are
assembled. The tolerances on the frequency errors for the RDDS structure are about
one MHz for the fundamental mode and a few MHz for the dipole modes. At the X-band
frequency, these correspond to errors of a micron level on the major cell dimensions.
Such a level of resolution requires highly accurate field solvers and vast amount of
computer resources. A parallel finite-element eigensolver Omega3P was developed at
SLAC that runs on massively parallel computers such as the Cray T3E at NERSC. The
code was applied in the design of the RDDS cell dimensions that are accurate to
within fabrication precision. We will present the numerical approach of using these
codes to determine the RDDS dimensions and compare the numerical predictions with the
cold-test measurements on RDDS prototypes that are diamond-turned using these
dimensions.

* Work supported by the Department of Energy, contract
DE-AC03-76SF00515.

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