Who is we? It sounds like you're working on a SF story, is that right?we are considering the ignition with a laser or relativistic electron
Have you read about Inertial Confinement Fusion with lasers? You should look at the size of the target spheres and read how much energy is released per shot. I don't know if that qualifies as your "bomb" or not. Also, I guess you need to include the size of the building housing the laser system in the "size" of the "bomb"...So you can make small fusion bombs as much as you want
Maybe you can modernize the concept of Project Orion. https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)Thank you! Actually, I'm considering this kind of bombs for advanced space propulsion systems, not on the Earth. Anyway thanks for your suggestion.
Winterberg has done some work along these lines.Maybe you can modernize the concept of Project Orion. https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)