Warp, lots warp. There's quite a few bombs around that use the effect for sustained fusion.
The big green one with the VIBR for example
edit. the effect is much more noticable with velocity turned off(simulation options or press Y).
I think I figured it out. exot was used, produced warp that decayed into elec. these elec went and "enriched" the deut, and created a sustained reaction. I just tried this out, and I got more deut coming out than I put in.