Aha!

Search for this term, and check out the PDF from the SLAC people at Sanford: CHANNELED PARTICLE ACCELERATION BY PLASMA WAVES IN METALS

You'll get this link.

I obviously am not the first to think along these lines.

And people say I'm just crazy.

The fields inside solid materials are to charged particles inside their structures very very strong compared to the fields we make in accelerators. In fact, what that paper describes is actually far stronger than is necessary to fuse protium, deuterium, or tritium, or even boron and protium.

See the Wiki entry on aneutronic fusion.

Anyhow, it should be possible to create a system that easily drives an ionized fuel source to fuse and release energy. The trick then is to immediately capture said energy and transfer some back to the generator and use the rest across a load. Going beyond break-even should be relatively simple if we can figure out the absorption method properly. I'm thinking something like a solar cell, but for higher energy radiation.

You know, you can channel and even bend gamma rays like light and they do this for astrophysics. Perhaps a metallic crystalline matrix for intercepting and moderating gamma rays and x-rays down to more manageable wavelengths and then knocking electrons loose creating a potential. We'd have to be able to get rid of the charged ions in an aneutronic system, or allow neutron scattering but I think the proper beryllium compounds might work there too.

This is going to require quite an amount of calculations for some very enterprising people across a dozen disciplines starting with molecular mechanical physics to design the appropriate matrices and then chemical engineers to consider how to make those compounds and grow the crystals and perhaps engineers to figure out how to do molecular compositing...

But... a solid-state fusion battery pack should be possible.