ELI5. Why do you need to use heavy hydrogen to start a fusion reaction?

Question

I am pretty sure the sun fuses just standard one proton hydrogen. So why do we need to use deuterium and tritium for our bombs?

In: Physics

Answer 1

The sun actually does a 2 step process

It fuses 2 protons, which almost immediately beta decays into dueterium.

After that, it either fuses a proton with dueterium to make helium-3 or fuses 2 dueterium into ordinary helium-4

By starting with heavy hydrogen, we can skip that first step which makes the reaction easier to get going