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p>Changes in program capabilities usually occur when I am involved in a consulting project. While working intensively with a program, I invariably find that there is a missing feature or that an existing feature is irritating. Both aspects apply to the
CircBeam and
RectBeam tools of
OmniTrak.
To review, the CircBeam tool creates a particle file (PRT) to represent a beam with an approximately uniform current density with specified radius, total current, species and energy. As input to OmniTrak, the particle file provides a useful starting point for many simulations. In the current project, I wanted to model transformations of the distributions of a high-current electron beam in a bending magnet. In its previous form, the CircBeam tool generated beams parallel to the x, y or z axis. In the bending magnet application, it is necessary to assign convergences (or divergences) in the vertical and horizontal directions to seek a match (i.e., the beam has the same shape at entrance and exit). I added new capabilities to both the CircBeam and RectBeam tools. (For reference, the RectBeam tool generates a uniform-current-density beam with a rectangular cross section.) At the same time, I made the tools easier to use.
Figure 1 shows a screenshot of the CircBeam dialog. The new parameters are shown at the lower right (red arrow). The parameters are the effective focal lengths for transverse divergence. If the primary axis is z, then initial particle angles in the x and y directions are assigned according to
dx(n)/dz = x(n)/XConv,
dy(n)/dz = y(n)/YConv.
A positive value of XConv gives a diverging beam in x. A negative value gives a converging beam. If XConv = YConv, the beam has a radial divergence (or convergence).
Figure 1. Screenshot of the CircBeam tool dialog.
While adding the features, I fixed several vexing issues:
- Better choice of default parameters.
- Consistent formatting of numbers in standard and scientific notation.
- During a session, OmniTrak remembers the tool settings so you can return to the dialog and make small changes without re-typing all the information.
- Upon completion, the tool opens a standard Windows save dialog so you can assign a name and location to the output particle file rather than the default CIRCBEAM.PRT in the current directory.
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