The PARMELA FEL model has been a very important tool to understand and
setup the injector since the early stages of the 10kW Upgrade IR FEL
commissioning. We will discuss why this is true and how we have
achieved confidence in the model. A very limited set of beam-based
measurements have been performed in the injector, but an extensive
modeling has been done in an effort to compare the behavior of both,
machine and model by observing the derivatives of a particular
diagnostic as a function of a particular variable, instead of just
comparing absolute values. Several modifications to the PARMELA FEL
source code have been implanted to make the modeling results a little
bit closer to reality. These modifications will also be described.
Talk Slides: (Slides)