The fission bomb implodes, giving off X-rays.
These X-rays heat the interior of the bomb and the tamper; the shield prevents premature detonation of the fuel.
The heat causes the tamper to expand and burn away, exerting pressure inward against the lithium deuterate.
The lithium deuterate is squeezed by about 30-fold.
The compression shock waves initiate fission in the plutonium rod.
The fissioning rod gives off radiation, heat and neutrons.
The neutrons go into the lithium deuterate, combine with the lithium and make tritium.
The combination of high temperature and pressure are sufficient for tritium-deuterium and deuterium-deuterium fusion reactions to occur, producing more heat, radiation and neutrons.
The neutrons from the fusion reactions induce fission in the uranium-238 pieces from the tamper and shield.
Fission of the tamper and shield pieces produce even more radiation and heat.
The bomb explodes.
