Is the major barrier to fusion power the tendency of very hot plasma to destroy the container? Or not? Would zero gravity solve the problem? Or is this a relatively trivial problem?
Bonus question: would we get any mileage from creating a solar array closer to the sun and beaming the energy to a microwave collector in orbit around the earth?
ETA: No, I haven’t taken college level physics and do not understand orbital mechanics or the relationship between speed and distance from the central body.
It is not clear to me how you think anti-gravity would help. The problem is to compress the plasma without it touching the sides of its (physical) container (which it would melt. A gas, or plasma, in a container does not touch the sides due to gravity, just to the general tendency of any gas to fill any container, due to the kinetic energy of its molecules.
Stranger’s reference to gravity was an allusion to how fusion happens in stars. That sort of “containment” of the plasma relies on their being a shitton of gravity (which comes from teh enormous mass of the plasma that is there, comprising the star. You don’t want anti-gravity there, you want lots of regular gravity.
I suppose if anti-gravity meant some sort of gravitation-like repulsive force (to me, it tends to mean just the nullification of gravity, but what the hell, it is not real anyway) then I suppose one could imagine using it to to confine a plasma (if you could also make it somewhat directional), but it would need to be an awfully strong repulsive force, and regular gravity is very weak, even compared to the magnetic forces that fusion research mostly relies upon now. If anti-gravity is gravity’s opposite, one would imagine that it would take an enormous amount of energy to create a strong repulsive force (just as it takes an enormous amount of mass to create even a moderately strong gravitational attraction, such as the force produced by Earth that keeps our feet on the ground).
Holding the plasma up against gravity isn’t the issue. The issue is keeping the plasma contained and preventing it from expanding and touching the walls of the container. It wouldn’t make much of a difference if the reactor was in free fall.
Also, the problem with letting the plasma touch the walls of the container isn’t so much that the walls would melt, as that touching them would drain too much energy out of the plasma and cool it off. The plasma may be very hot, but it’s also thin, and the walls of the reactor have much, much more thermal mass than the fairly thin plasma.
FWIW, my problem (one of many) was a tenuous understanding of the state of matter known as plasma. If I’m correct, plasma is, “Like a gas with electro-magnetic properties”, as opposed to, “Like mercury or a corn starch gelatin or a lava lamp”. So gravity doesn’t matter so much. I am unclear where my mistaken impression formed.
The fact “plasma” is also used to refer to the liquid fraction of blood is probably the source of a lot of folk’s confusion. A lava lamp is (very!!!) vaguely similar to blood in that it is lumps of smooshy solids in a thick semi-transparent liquid. That’s about the end of the similarity, so don’t press too far with it.
As far as space-based solar power goes, there is no real advantage in placing the collectors much closer to the Sun, at least not if your main objective is providing power to the Earth. The ambient sunlight in Earth Orbit is quite powerful enough to justify collection, but only if the solar power satellites can be made and launched very cheaply. Adding the additional expense of placing the satellites closer to the Sun would make the exercise even more difficult to justify.
Eventually there could be an economic case for placing solar power satellites much nearer the Sun, but only if we can establish an industrial economy on Venus and/or Mercury.
In terms of the four fundamental forces of the universe (strong nuclear, weak nuclear, electromagnetism, and gravity) the force of gravity is essentially non-existent at the atomic level.