by iamlucky13 » Mon Apr 07, 2008 6:54 pm
I'm not an astronomer, but I am as avidly interested in energy, including fusion as I am in astronomy.
A lot of early fusion research involved understanding the sun, and separately, developing nuclear weapons. Probably back in the 1960's or so, most of the common details had been worked out, and fusion energy and weapons research became mostly independent of astronomy.
As far as identifying fuel for fusion in space, if that's what you were curious about, it's not necessary. We have abundant hydrogen on earth. Currently, fusion research is being done using deuterium and tritium as fuels. Deuterium makes up 0.015% of all hydrogen on earth, which might not sound like much, but there is a lot of hydrogen on earth. Both deuterium and tritium can also be produced in laboratories or as a byproduct in nuclear reactors.
The process isn't quite clean, but it is a lot cleaner than fission with uranium, etc. The reaction product is ordinary helium, hydrogen fusion releases a lot of high energy neutrons. These neutrons are absorbed by metals in the reactor wall, causing them to become low-level radioactive. These metals are much, much less dangerous and easy to dispose of than spent uranium, but still somewhat of a concern.
There is some hope, once hydrogen fusion is perfected, for switching to helium-3 fusion. This requires much higher temperatures and is therefore harder to achieve, but it releases no neutrons. Some space enthusiasts view this as a reason to push hard at manned space exploration as there are higher levels of He-3 on the moon than on earth. However, we are first of all a long, long ways away from being able to use He-3 fusion, and secondly even on the moon you would have to mine millions of tons of dirt for a few pounds of He-3. It can be made artificially on earth much, much easier, in my opinion.
Another benefit of most potential fusion reactor designs is that the total amount of fuel in the reactor at one time is much to low for a major accident to occur. Of course, nuclear fission reactors are increasingly safe, most of them outstandingly so, but fusion is even better in that regards. A complete failure of a Tokamak reactor would only release about as much energy as a small artillery shell, easily contained and trivial compared to the huge steam explosion that destoyed the core of the Chernobyl reactor. In the fusion case, the reaction would stop immediately, where as at Chernobyl it continued for a long time, in addition to a graphite fire which helped spread the radioactive fuel.
I'm not an astronomer, but I am as avidly interested in energy, including fusion as I am in astronomy.
A lot of early fusion research involved understanding the sun, and separately, developing nuclear weapons. Probably back in the 1960's or so, most of the common details had been worked out, and fusion energy and weapons research became mostly independent of astronomy.
As far as identifying fuel for fusion in space, if that's what you were curious about, it's not necessary. We have abundant hydrogen on earth. Currently, fusion research is being done using deuterium and tritium as fuels. Deuterium makes up 0.015% of all hydrogen on earth, which might not sound like much, but there is a lot of hydrogen on earth. Both deuterium and tritium can also be produced in laboratories or as a byproduct in nuclear reactors.
The process isn't quite clean, but it is a lot cleaner than fission with uranium, etc. The reaction product is ordinary helium, hydrogen fusion releases a lot of high energy neutrons. These neutrons are absorbed by metals in the reactor wall, causing them to become low-level radioactive. These metals are much, much less dangerous and easy to dispose of than spent uranium, but still somewhat of a concern.
There is some hope, once hydrogen fusion is perfected, for switching to helium-3 fusion. This requires much higher temperatures and is therefore harder to achieve, but it releases no neutrons. Some space enthusiasts view this as a reason to push hard at manned space exploration as there are higher levels of He-3 on the moon than on earth. However, we are first of all a long, long ways away from being able to use He-3 fusion, and secondly even on the moon you would have to mine millions of tons of dirt for a few pounds of He-3. It can be made artificially on earth much, much easier, in my opinion.
Another benefit of most potential fusion reactor designs is that the total amount of fuel in the reactor at one time is much to low for a major accident to occur. Of course, nuclear fission reactors are increasingly safe, most of them outstandingly so, but fusion is even better in that regards. A complete failure of a Tokamak reactor would only release about as much energy as a small artillery shell, easily contained and trivial compared to the huge steam explosion that destoyed the core of the Chernobyl reactor. In the fusion case, the reaction would stop immediately, where as at Chernobyl it continued for a long time, in addition to a graphite fire which helped spread the radioactive fuel.