Let’s imagine that we have two (ideal) monolayers of hydrogen in vertical position. In reality, it might be impossible to get hcp structure with one layer of hydrogen atoms, but that’s not a dealbreaker. We can either use more hydrogen atom layers (more energy will be released too!) or we can use emerged fcc structure. What factors we must take into consideration in order to be successful? The initial requirement is that introduced protons must have anti-parallel spins (anti-parallel spin vectors in ToEbi terms) and they must contact with their spin axes head-on.
FTEP flux from protons keep the protons on a same layer in a required alignment. But before we put those (mono)layers together we have to manipulate them separately with magnetic fields to make sure that they have that required spin pattern (see picture). After that, we have annihilation enabling setup ready to go! But we won’t go just yet, we have few other things to consider.