From 2D to 1.5D: Reduced Order Simulations with the Large-Signal Code TESLA

This work presents results of the study, which involves modifications in the algorithms of the well-known 2D large-signal klystron code TESLA with a goal to improve its performance by simplifications in the physics of its model. The proposed modifications are based on the idea to reduce number of degrees of freedom of particle's motion from 3 down to 1 by restricting their motion along Z-axis only. Essentially, this will assume that magnetic field is infinitely large and one can completely ignore radial motion of particles as they will be “frozen” and allowed move in one direction only. Such modification in effect will reduce dimensionality of the algorithm from 2D down to 1.5D as a price to pay for proposed simplifications in the model. We will discuss pilot results of modeling by using the modified, reduced order algorithm, making main emphasis on advantages and disadvantages (“gains and losses”) of such step.