JET - Nuclear Fusion Research
Nuclear fusion is the process powering the Sun and stars, and a worldwide research programme is under way, aimed at harnessing fusion energy to produce electricity on Earth.
Global demand for energy continues to grow year by year as the world population expands and society becomes more and more dependent on energy supplies. The need to find new sources of energy is becoming increasingly important as environmental concerns mount over the emission of CO2 from burning fossil fuels.
The international record for fusion energy production of over 16 Megawatts is held by the Joint European Torus or JET in England. JET is the world’s largest nuclear fusion research facility and it has come closest to demonstrating fusion’s feasibility.
JET’s fusion method consists of a doughnut-shaped vacuum chamber surrounded by magnets.The aim is to heat hydrogen atoms to temperatures of up to 10 times higher than the centre of the sun, which causes them to break apart and form into plasma. Plasma is a form of matter achieved only by lightning under normal circumstances on Earth.
Within this plasma, atomic nuclei re-form to produce helium and in the process release an enormous amount of energy. The great challenge of these experiments is confinement.
Confining plasma with lines of magnetic force has been compared to trying to confine jelly with rubber bands. As the temperature increases, impurities from the vessel wall enter the plasma, causing major problems.
The success of JET, in terms of optimising plasma stability and confinement, has led to the design of the next step device - ITER. ITER is an international collaboration with seven partners (EU, Japan, USA, South Korea, Russia, China and India) - and is a more advanced, larger version of JET.
It will be capable of producing 500MW of fusion power (ten times that needed to heat the plasma). By comparison, JET can only produce 70% of the fusion power needed to heat the plasma. After much political debate, the go ahead to build ITER at Cadarache in France was given in June 2005. ITER will take ten years to build and should operate from 2015.
The fast track to commercial fusion power is a strategy designed to ensure that a demonstration fusion power station puts electricity into the grid in 30 years' time.