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Phenomenal Physics Q&A
Q: How close are we to developing energy from nuclear fusion?
A: Nuclear fusion has been the subject of ongoing research for approximately 50 years. The idea behind nuclear fusion is to fuse isotopes of light elements into a heavier element. This is the same process used by stars to generate energy. One example of a reaction is demonstrated with the following equation:
3H + 2H →4He + neutron + 17.6 MeV
For every reaction, 17.6 MeV (mega-electron volt) of energy is produced.
It is important to note that at present we can reliably produce an “uncontrolled” fusion reaction. This is the mechanism behind the H-bomb. But to capture and use energy, a controlled, sustainable reaction is needed.
Research nuclear reactor at southeast Portland’s Reed College (Source: Oregon Live.)
Present-day science: Nuclear fuel rods (Source: The Belfer Center for Science and International Affairs, Harvard University.)
A joint international project called the International Thermonuclear Experimental Reactor (ITER) is currently being built in France. This facility is based on the tokamak fusion reactor design, where deuterium and tritium, two hydrogen isotopes, are heated to millions of degrees to form hot plasma; magnetic fields are then used to confine the plasma and produce energy from fusion reactionsis a major stepping stone toward solving the problem of sustaining a controlled fusion reaction.
So, back to the original question, and this time with the addition of the word “sustainable”: How close are we to developing sustainable energy from nuclear fusion? That is a difficult question. In short, we still have work to do. It is possible that in the next 50 years we will have a safe and reliable method suitable for harnessing energy from controlled nuclear fusion. Once we have the method, the infrastructure still must be built. So, fusion technology will likely be a viable energy source 75 100 years from now. Today, we have much research ahead before we are able to harness energy for commercial purposes from fusion reaction. Incidentally, the ITER project has a goal of producing 10 times more energy than it uses by the year 2028.
tokamak is a device using a magnetic field to confine a plasma in the shape of a torus.
A “torus” shape.
Achieving a stable plasma equilibrium requires magnetic field lines that move around the torus in a helical shape. Such a helical field can be generated by adding a toroidal field (traveling around the torus in circles) and a poloidal field (traveling in circles orthogonal to the toroidal field). In a tokamak, the toroidal field is produced by electromagnets that surround the torus, and the poloidal field is the result of a toroidal electric current that flows inside the plasma. This current is induced inside the plasma with a second set of electromagnets.
The tokamak is one of several types of magnetic confinement devices, and is one of the most-researched candidates for producing controlled thermonuclear fusion power. Magnetic fields are used for confinement since no solid material could withstand the extremely high temperature of the plasma.
Tokamaks were invented in the 1950s by Soviet physicists Igor Tamm and Andrei Sakharov, inspired by an original idea of Oleg Lavrentiev. (Source: Wikipedia.)
Personnel (August 2013) laying the foundations for ITER’s tokamak, which will contain hot plasma. (Source: BBC News.)
What is Phenomenal Physics?
As a reminder, or for those new to our program, Phenomenal Physics is a program intended to enhance the education and interest of middle and high school students in science. Our goal is to build relationships and continue to expand the program to offer scholarships to students and grants for the purchase of lab supplies and equipment for use in local schools. While the program is heavily rooted in science education, it is free and available to everyone interested in solving everyday problems.