Part 2 of 2 Parts (Please read Part 1 first)
     It turns out that the conditions necessary to trigger nuclear fusion are an extreme challenge for human science and technology. Fusion works by combining light element nuclei into heavier element nuclei. When two hydrogen atoms are smashed together hard enough, they fuse into helium. The new atom that is formed by the collision has less mass than the sum of its parts. The balance of the mass is converted to energy via the E=MC2 mass-energy equivalence.
     The above description of the fusion process has been simplified. The atoms actually require a multi-step reaction to achieve fusion. Nuclear fusion produces net energy only at extreme temperatures and pressures. The temperatures required are on the order of hundreds of millions of degrees Celsius. This is much hotter than the core of our Sun and too hot for any known terrestrial material to withstand.
     In order to get around this problem, researchers are using extremely powerful magnetic fields to contain the hot plasma and prevent the plasma from coming into contact with the walls of the fusion reactor. This requires a huge amount of energy.
     Stars are able to accomplish fusion because they are so massive, and their gravitational fields exert the pressure required. The gravity of the Sun is thirty times the gravity on the surface of the Earth.
     Every fusion experiment to date has been energy negative. This means that they have all consumed more energy than they have generated. So, they are useless as electricity generators. Getting the initial fusion reaction to trigger is not difficult. The problem is to keep it going to generate positive energy. Building commercial fusion reactors will require some very sophisticated feats of engineering which are not yet understood. Researchers are confident that they are close to constructing a nuclear fusion reactor that will produce more energy than it consumers.
     The Saint-Paul-les-Durance, France-based International Thermonuclear Experimental Reactor (ITER) currently under construction is the largest fusion reactor in the world that is dedicated to developing commercially viable fusion. ITER is funded by six nations, including U.S., Russia, China, Japan, South Korea, and India. The ITER team plans to construct the world’s largest tokamak fusion device. This is a donut-shaped container that will produce five hundred megawatts of thermal fusion energy. The estimated cost of ITER will be about twenty four billion dollars with a delivery date estimated at 2035. The giant machine will weigh in at an impressive twenty-three thousand tons and will occupy a building about two hundred feet high.  
      One of the important advancements that are encouraging is the development of a new superconducting material which is basically a steel tape coated with yttrium-barium-copper oxide, or YBCO. This new material allows researchers to construct smaller and more powerful magnets. These new magnets will require less energy to trigger the fusion reaction.
     The European Union’s joint project to construct ITER will require eighteen niobium-tin superconducting magnets also called toroidal field coils to contain the one hundred and fifty million degrees Celsius plasma. The magnets will generate a powerful magnetic field equal to about twelve tesla or a million times stronger than the Earth’s magnetic field. Europe will construct ten of the toroidal field coils. Japan will manufacture nine.
     It will be another decade before a full-scale demonstration power plant will be built using the lessons learned from ITER. The ITER site construction is about eighty percent complete.