First a definition for this question, because there are many kinds of sci-fi out there and they sometimes liberally use cool sounding words without explaining them:
A disruptor is a kind of weapon that weakens, or “disrupts”, either material bonds (breaking a material into molecules), molecular bonds (breaking a molecule into atoms), or atomic bonds (breaking an atomic nucleus into protons, netrons, and free electrons. Almost like instantly turning into plasma).
Temperature can do these things, but the idea behind a disruptor, specifically, is that it happens through some kind of catalyst, rather than brute-forcing with insane amounts of heat.
Would such a weapon physically be possible (even if we don’t know how to make them just yet)?
How would a target realistically behave when hit by a disruptor?
So…. Wouldn’t a fission bomb be a “disruptor bomb”?
What you describe sounds an awful lot like the reaction in nuclear fission (with neutrons knocking a cascade of other neutrons out of atoms.).
Maybe a disruptor beam is just a neutron beam that causes a cascading reaction in more than just the typical “fissionable” materials. This is where we get the fun technobabble!