In other words, why is it so hard to get the Q value above 1 (ration between energy output and input)
In: 179
Essentially to make hydrogen fuse into helium (and release the massive amount of energy that makes it worthwhile) you need to apply enormous heat and pressure.
You can apply a truly ridiculous amount of heat, and a bit of pressure.
Or you could apply a little heat and a whole lot of pressure.
The Sun actually works off the second one.
Its sheer mass is what induces fusion. The force of gravity squeezes the hydrogen so tight it actually merges into Helium. That and some heat to excite the atoms and make them a bit more amenable to merging, and you get a star.
The problem is that we don’t have a star-sized amount of mass to squeeze the atoms together.
So we have to work with what we’ve got.
Turns out if you heat it up more, you don’t need as much pressure.
Gravity is pretty much free, the sun fuses just by sitting there.
Pouring lasers and whatever other methods of heating we can get into a mass of hydrogen (or other fuseable gas) costs a lot of energy, as does containing and squeezing it all with magnetic fields so it doesn’t melt the reactor.
The challenge is basically to find a means of heating and squeezing the fuel that takes less energy than we release by merging the atoms together.
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