What are the details about the nuclear reactions that power the Sun?

When two protons collide, the strong nuclear force is not large
enough to hold them together against the electrical repulsion
because they have the same charge (like charges repel). So
in that instant when two protons are together, one of them
has to change into a neutron, which has no charge. This
happens very rarely, but then there are lots of interactions
happening in the sun. Since protons have two up quarks and
one down quark and neutrons have two down and one up quarks,
clearly an up must become a down. This can happen through
the weak nuclear force. A proton becomes a neutron + a positron
+ neutrino. The basic set of reactions that fuel the sun are

proton + proton --> deuterium (proton+neutron) + positron + neutrino
deuterium + proton --> helium-3 (2protons+neutron) + photon
helium-3 + helium-3 --> helium-4 + proton + proton

So hydrogren nuclei (single protons) are changed into helium nuclei.]

I hope this helps,
Sincerely
Jennifer Johnson

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