>>12826881anon, all you need is a big, seriously big i mean, light gas gun. Ideally a Voitenko compressor. If you can accelerate a small block of hydrogen rich mass, to 100 km/s, you would basically reach the peak cross section for fusion.
This only work for macroscopic mass (say a few kg) because they have critical thermal inertia. A small mass or worse, a particle beam, would cool down too fast.
