Nuclear fusion is similar to nuclear fission in that the binding energy of the products is much higher than the starting nuclei.  The process to achieve this, however, is based on combining nuclei rather than breaking them down.  At temperatures greater than 100 million Kelvin, the small nuclei of tritium and deuterium will combine to form larger, more stable helium atoms while releasing an amount of energy proportional to the change in mass (mass defect) or equal to the difference in binding energies before and after the reaction.

Nuclear fusion powers the Sun, which has enough hydrogen to maintain its present rate of energy production for another 6 billion years. On Earth, hydrogen is abundant in the water, which, in theory, could provide a seemingly infinite supply of clean, safe nuclear energy.


Watch This
Watch the video " Sun Flares ". Courtesy of SOHO (ESA & NASA) This video shows the energy released by nuclear fusion on the surface of the Sun. When the Sun's magnetic field fluctuates it allows massive amounts of plasma to arc off into space.  The arcs are often larger in diameter than Earth.



Commercial fusion reactors have the potential to provide phenomenal amounts of non-polluting electrical energy.  The EFDA (European Fusion Development Agreement) sponsors JET (Joint European Torus), a commercial fusion reactor development site.  EFDA scientists are researching how to safely recreate the reaction that powers the Sun to produce electricity on Earth.  They used the information gathered from the JET project to design a large reactor called ITER, which is scheduled to begin operation in 2016.  When complete, ITER will be the biggest fusion furnace ever built, twice as large as any previously built, and will produce plasma at temperatures of hundreds of millions of degrees Celsius.  The video "Inside a Reactor" shows the inside of the JET reactor during a plasma experiment. 

Read
Read "Fusion" on pages 821 to 823 of your physics textbook.  Page 821 provides more detail on the reactions occurring on the Sun and includes references to the products released (neutrinos, positrons or anti-electrons, and gamma rays).


Try This
Read "Example 16.16" and complete "Practice Problem" 1 on page 822 of the textbook.  NOTE: For Practice Problem 1.(a), the answer should be 3.7 x 10 36 . For 1.(b), the answer should be 3.1 x 10 27 kg.