•Have
lots of hydrogen (p+ and e-) – what can we
make from it?
•
•If 2He (2 protons, 0 neutrons) were stable,
fusion would be “easy”
–Run
two protons into each other at high enough speed to overcome Coulomb
repulsion
–Once
they get close enough strong force takes over, and holds them as nucleus
–
•“Unfortunately”
2He
isn’t stable
–To
get stable He need to add one or two neutrons to:
•Increase
Strong Force, without increasing Coulomb force
–Not
really “unfortunate” – If 2He were stable:
•Sun
would burn energy way too fast – and would have gone out by now
–
•Will
need to rely on weak force to convert proton to neutron – fusion will be
slow
–In
solar fusion no excess neutrons lying around
–Hydrogen
bombs use deuterium: 2H = (p+ n)
or tritium: 3H = (p+ n n) to provide it