For sustainable fusion reaction to be realized, the tritium and deuterium plasma must be exposed to temperatures of over 100 million °C using powerful heaters with minimal loss of energy. To maintain that high temperature, the hot plasma must be placed a distance from the reactors interior. Since the plasma is an electrically-charged gas, it is held by magnetic fields, which control and supply heat while they allow the charge-less neutrons to escape.
In a tokamak, a doughnut-shaped structure keeps the plasma in position. A magnetic field in created using special coils thus resulting in the spiral movement of plasma particles without coming into contact with the walls of the vessel.
The main idea behind the European fusion research ITER experiment is topnotch technology referred to as ‘Toroidal magnetic confinement fusion’. In the ‘doughnut shaped’ chamber that forms a continuous tube, plasma is isolated from the surrounding areas resulting in reactions. Flow of electrical current in the plasma and the electromagnets surrounding the vessel induce generation of both toroidal and poloidal magnetic fields. A centrally placed solenoid in the torus partly contributes to the current that acts as the main transformer winding. This ensures that the plasma particles, and their charges are kept at a distance from the wall of the reactor.
Three conditions must be met in order to achieve disposable fusion power output in a deuterium tritium reactor. These conditions are: extremely high temperatures above100 million °C, density of plasma particle should not be less than 1022 particles per cubic metre and a one-second energy confinement period for the reactor. Comprehension of plasma properties is necessary for proper control.
Some factors to consider include the mode of heat conduction, how loss of particles from the plasma takes place, the stability and how impurities can be removed from the plasma.
Maintenance of plasma temperature is a great challenge in fusion research. Apparently, unwanted particles have a cooling effect on the plasma, and they need to be removed. More heating is required to achieve the high temperatures required although plasma is heated by the electric current induced by the transformer arrangement. This is done by injection of highly energetic fusion fuel (deuterium and or tritium) beam particles which upon collision with plasma particles, they transmit their energy and radio frequency heating resulting in high-power radio waves that is taken in by the plasma particles.
Europe has a good history of fusion technology.
The Joint European Torus (JET) located at Culham (UK) is the largest fusion facility in the world besides being the only one able to apply the Deuterium-Tritium fuel combination. JET has so far achieved the set objectives and also surpassed some of them. In 1997, it managed to reach a global fusion power production of 16 MW and a Q of 0.65.
Europe has also been advancing on knowledge acquired through the Tore Supra tokamak in France, which was the first large tokamak that used superconducting magnets; Germany’s ASDEX device that has ITER-shaped plasmas; the stellarators TJ-II of Spain and Germany and Italy’s reversed pinch device RFX.
Source: Fusion for Energy (Europa)