Wakefields in the Trace 3-D Code

TRACE 3-D is an interactive code that calculates and displays the envelopes of a bunched beam through a user-defined transport system. Accelerating elements and linear space-charge forces are included. The beam is described by a 6-D sigma matrix of second moments. We have extended the capabilities of this code to include effects, such as wakefields, related to the variation of the beam bunch in the longitudinal direction. This nonlinear capability was implemented by adding centroid tracking and describing the beam by a collection of slices, each described by a 6-D centroid and sigma matrix. External forces, space-charge forces, and wakefields act on the collection of beam slices. Results are presented in terms of an overall sigma matrix, computed by combining the slice distributions. The new TRACE 3-D has been integrated with an improved graphic user interface (GUI) based on the Shell for Particle Accelerator Related Codes. This new approach to modeling wakefields demonstrates the flexibility of extending the capabilities of moment codes to handle important physical effects, and the rapid incorporation of the new capabilities into the graphic interface illustrates the ease of customizing the new GUl. The wakefield model and features of the new interface are presented.