Fusion reactor?

Today I read a story in the newspaper about how Japan is pulling out of the running of a multi-nation fusion reactor, leaving France as the likely host country. This is the first I’ve ever heard of a fusion reactor… is it a giant experiment? Has fusion been attempted before? Who’s taking care of the bill?

New stuff. Experimental. Don’t know about this particular one, but it’s the ‘holy grail’ of energy production.

H + H = He + heat. Clean, wonderful, and incredibly tough to do.

Fusion experiments have been running since the 50’s. Controlled ones since the 60’s.

There are a number of different methods to achieve controlled fusion. The best know is the tokomak. There you have a torous shaped chamber with very strong magnetic fields that contain a stream of protons and deuterium at very high temperatures link. The system gets pumped by microwaves to heat the gas to the point where fusion begins. If the plasma can stay hot enough a self sustaining fusion reactions begins. Otherwise the thing sputters out. Their still trying to achieve a long lasting breakeven point where the energy output is greater than the energy input. link

There are other approaches such as inertial confinement, where a small pellet of Deuterium is zapped by powerful lasers but the ITER project is likely the one you heard discussed.

Ignore the 's. Bad habit.

Just to clarify, Japan did not pull out of the project. It’s just a question on where to build it, and they gave in to other countries who wants it in France rather than Japan. From the Guardian:

Is it “sort of” a giant experiment. It has been delayed for several years because of the disagreement over this France/Japan issue, and due to the French/US recent diplomatic disagreement (the USA sided with Japan in part to “punish” France for the Irak war issue). An agreement has eventually be reached after the EU decided that it would go on without the US and Japan if needed and began to convince other countries (in particular Russia and China) to follow, after the “warming up” of US-French diplomatic relationship, and finally by giving some sort of compensation to Japan.
It’s “giant” in the sense that it’s a costly, large scale, international project.
However, it’s still only an experiment. The reactor isn’t expected to produce electricity in any significant amount. It will just be the most recent and costly experimental fusion reactor (there has been many of them build over the years). Even assuming that it would result in so significant progresses that an actual functionnal reactor could be build as a result, if you take into account the time needed to build it, to operate it, study the results, build another one, etc…we’ll likely have to wait for a couple more generations. I believe it will take something like 10 years just to build it, and maybe something like 15 years of experiments. So, it’s a large, long-term project, that might or might not result in significant advances that might or might not be later implemented…maybe 40 years down the road. So don’t hold your breath…

I once had the job of advising a consultant (how’s that for ducking responsibility?) to our city council on the advisability of going for a small piece of the sustained fusion reactor research dollar. My conclusion was that it looked like a pretty good cash cow for the next 100 years (WAG). To that time (ca 1990) no reactor had put ou more power than it took in. A plot of the ratio of output to input for tokomak reactors as of function of time, i.e. the year in which the measurement was made, resulted in a curve sort of like a 1-e[sup]-at[/sup] curve and seemed to be approaching 1 assymptotically. It sure looked to me at that time as if such a reactor wouldn’t ever produce a self-sustained reaction with some saleable excces power output or at least it would take a very long time if one could ever result. It is now 15 years later and I think that is still the case.

This Auntie Beeb News Article may be of interest.