There's some info here on the (mis-spelled) rules cards regarding the ion jackpot/ Click to enlarge.
http://www.marcospecialties.com/pinball-parts/755-5001-00
Quoted from grantopia:I can't find a ton on the rules for this game. Does anyone have any insight into how the ion cannon jackpot value increases? I thought it was tied to the bonus amount, but played a game last night when I had ALOT of bonus built up and the jackpot was only 100K...next ball 400K. Anything concrete on how this works? Thanks!