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**

**CASA Seminar**

**
Thursday, May 25, 2006, 3:30 PM**

ARC, 231/233

Advances
in Electromagnetic Modeling: Advanced Algorithms,

Self-consistency, and Parallelism

John R. Cary

Tech-X Corp. and University of Colorado, Boulder

Multiple
advances in algorithms, computation, and computational hardware have
made

electromagnetic calculations of large, complex systems possible.
So-called charge-conserving

algorithms allow fully self-consistent computations, in which the
self-generated wake fields affect

the dynamics of the particles generating the fields. Cut-cell (or
embedded) boundaries allow the

accurate computation of modes for complex shapes, such as crab cavities
with multiple

resonators and both low-order mode dampers and high-order mode dampers.
Inclusion of

emission processes enables the computation of multipactoring and
similar effects. New implicit

algorithms that conserve charge are stable for any time step. These
allow one to compute

systems with structures small compared with the characteristic
wavelength of the system in

reasonable time. Algorithms that parallelize well allow one to take
advantage of the largest

computational hardware. This talk will discuss these algorithmic and
computational advances,

their implementation in VORPAL,** a flexible, object-oriented,
massively parallel modeling

application, and their application to beam physics. Example
computations for cavities,

photoinjectors, and compact acceleration will be presented.

* Work in collaboration with J. Amundson, R. Busby, D. L. Bruhwiler, R.
Busby, J. Carlsson, D. A. Dimitrov, P. Messmer, C. Nieter, N. Sizemore,
D. N. Smithe, P. Spentzouris, P. Stoltz, R. M. Trines, S. Veitzer,
W.-L. Wang, G. Werner

** C. Nieter and J. R. Cary, "VORPAL: a versatile plasma simulation
code", J. Comp. Phys. 196, 448-472 (2004).

Talk Slides: (Slides)