[pmayrgundter]

I think that's true for the easier to ignite reactions like D-T, but there are others that are aneutronic, eg Proton+Boron. It's much harder to initiate, but the fuel is cheap and the energy output higher.

"Aneutronic fusion loses much of its energy as light... Since X-rays can go through far greater material thickness than electrons, many hundreds or thousands of layers are needed to absorb the X-rays." https://en.m.wikipedia.org/wiki/Aneutronic_fusion

Now the Army research in the OP doesn't go up to XRay frequencies, but I haven't found a hard upper limit to the coupling effect yet.

[infogulch]

What if the fusion container was an x-ray laser? Could it induce fusion, where emitted xrays are in phase with the laser? I can imagine that an extreme high energy, directable, phase aligned, giant laser power source could be pretty useful.

[pmayrgundter]

Yeah, the NIF experiment is laser driven fusion, but I don't think that even being in phase would help capture the light. Not sure. It's the Ryberg coupling with light (without the usual requirement of just lots of mass/shielding) that's kind of unique here