I am pretty sure that is does normal type damage on units with the kT value indicated. And fighters don't have a computer core! But I would suggest you make your own test. I never tried it on planets too.
I corrected the target ability in my component file and now everything is fine.
Yeah, if it attacks fighters then it must be a problem in the combat code. Fighters don't have a computer core. Oh well, it's easy to just change the targetting to ships only.