Physics Section Activities 

Nuclear Fusion

     When two hydrogen nuclei collide at high speed, they may fuse together into a heavier nucleus, releasing energy. Similar fusion reactions generate the enormous energy produced by the Sun and other stars.

     While the ultimate goal of nuclear fusion research is to develop fusion power plants to generate electricity, research on fusion is still at an early stage. The main fuels involved would be deuterium and tritium, both heavy isotopes of hydrogen. Deuterium constitutes 0,0153% of natural hydrogen and can be extracted inexpensively from seawater.

     Tritium can be made from lithium, which is also abundant. The amount of deuterium present in one liter of water can produce as much energy as the combustion of 300 litres of gasoline, so there is enough deuterium in the oceans to accomplish the human energy needs for millions of years.

     The potential advantages of nuclear fusion energy include:

• An enormous supply of inexpensive fuel (deuterium and tritium).

• A long term, sustainable, economic and safe energy source for electricity generation.

• Minimal long lived radioactive products.

• Possible recycling of some reactor materials and unburned fuel.

• No greenhouse gas effect.

     The task of building fusion power plants is a great challenge involving the expertise of plasma physicists in many Member States. The deuterium-tritium fuel must be heated to about 100 million degrees centigrade in order to achieve fusion ignition. At these temperatures, the fuel becomes a fully ionized gas-plasma. The Physics Section is supporting research on two general methods of fusion: inertial confinement and magnetic confinement.

     Inertial confinement uses intense ion beams or laser beams to compress a pea-sized deuterium-tritium fuel pellet to extremely high densities, at which point shock wave heating then ignites the pellet. Fusion power plants using this technique would ignite fuel pellets several times per second in a large chamber, and the resulting heat would produce the steam used to generate electricity.

     Magnetic confinement uses extremely powerful electromagnets to contain and insulate the fuel plasma. A very high current is induced in a doughnut shaped plasma, and auxiliary heating (by microwaves, radiowaves or accelerated atom beams) is used to achieve temperatures of several hundred million degrees centigrade for several seconds. The temperature and density values that are possible to achieve with today's technology are close to what would be needed for a fusion power plant.

     The Physics Section is helping the Member States to build up knowledge on controlled nuclear fusion and is facilitating the research project to build a fusion power plant: ITER, the International Thermonuclear Experimental Reactor.

     In the meantime, many spin-offs relating to plasma physics and fusion technology are already benefiting society through improvements in materials (such as ceramic, metals and coatings), industrial processes (such as welding and waste removal), electrical technology, transportation and other scientific areas.

     The Physics Section maintains the World Survey of Activities in Controlled Fusion Research.