Allright, this is a plug for one of Tech-X's products relevant to IEC fusion. Tech-X sells a code VSim (previously Vorpal) that is used by many people to simulate IEC fusion concepts. Version 6.2 was just released ( http://www.txcorp.com/home/vsim/vsim-overview ). It's a parallel 3D relativistic PIC code which allows complex geometries externally applied electric and magnetic fields. It can be run in electrostatic mode as well as electromagnetic.
Also of note, the recent Iranian paper on IEC fusion used OOPIC Pro which was also a Tech-X product, but I believe it's been discontinued entirely in favor of VSim. As far as commercial competitors there is also MAGIC and LSP both owned by ATK. As a hobbyist, all these codes are very expensive, but for serious projects it seems like a tool like this is needed. Anyway, I haven't seen any of these tools mentioned in the forums (though I may be searching incorrectly) so here they are.