April 2003 Archives

Last night I changed the SimIon model to use one electrode for the entire cage and received much better agreement with the five fold symmetry.  In the previous model, each of the great circles was a separate electrode.  I know this was bone headed, as they are all at the same potential, but I won't go into the reasons why this came about.  The extra bonus is that the field calculation is about half as long.  Only two electrodes, not 7.  <heh>  I can be silly at times.

Finally got some time and dug into simulating the beast with SimIon.  Click here to download the SimIon geometry files.  Why was this hard?  Just figuring out the three dimensional rotation matrices, that's all.  Tedious, as the SimIon reference frame is a right handed, and the reference frame I had from my cad system is left handed.  Projection and a few sign changes later and I had the icosidodecahedron cage modeled as an electrostatic potential array (shown on the left).  Click on the image for the full size image.  It's the standard 3D isometric viewpoint of the icosi-grid as modeled in SimIon.