Story by KRISTIN ROBERTS
It's the stuff of science fiction movies: a futuristic-looking device that harnesses the power of the stars to yield unlimited electricity. Yet this storyline is coming to life now at the Institute of Physical Science in Hefei, China, where an impressive instrument generates power by controlling nuclear reactions.
The Experimental Advanced Superconducting Tokamak (or EAST) is a 400-ton machine composed of more than 10 complex parts that fill an area the size of three tennis courts. To understand what it does, we first have to have a little refresher on the most common state of matter in the universe — plasma.
Plasma is a charged gas found in the sun and other stars, but also in neon signs, florescent light bulbs and certain televisions. Unlike other gases, plasma can be influenced by electric and magnetic fields. And when plasma particles are heated up and collide, they can (like the sun) produce massive amounts of energy.
Using EAST, researchers are trying to create this kind of energy with the help of powerful magnets. At the center of the machine are more than a dozen 6-tesla, ring-shaped superconducting magnets that keep the plasma contained. Another set of magnets, oriented perpendicularly to the first, push the charged particles in the plasma toward each other, encouraging those critical collisions — known as fusion — that create the energy.
But this entire plan only works if the plasma can be heated to ultra-high temperatures — temps about 80,000 times hotter than lava. To do that requires a complex injection heating system and other specialized equipment.
Scientists are making progress. When EAST created its first plasma in September 2006, it generated an electrical current of 200,000 amps for three seconds at a temperature of about 20 million degrees Celsius. About a decade later, the machine reached 400 kiloamps for 102 seconds at temperatures up to 50 million degrees Celsius. In the next 15 years, scientists hope to produce steady-state operation of 1,000 seconds with plasma heated to 100 million degrees Celsius.
These ambitious goals are all part of the world's biggest fusion energy project, ITER. Based in France, ITER is a 35-country collaboration to build the world’s largest tokamak and change the future of energy. EAST serves as a test bed for ITER, laying a foundation for the ITER tokamak to create 500 megawatts of power (enough to power 250,000 homes for about 10 minutes), all from fusion. Now that's a sci-fi fantasy come true.
Photo courtesy of Institute of Physical Science.