Fusion: Stepping closer to reality

Fusion is getting closer and closer, and will be achieved perhaps within my natural lifetime.

“There have been dramatic advancements in our scientific understanding” over the past five to 10 years, Goldston notes. The basic conclusion: The “fire” in the type of reactor planned for ITER may not be as finicky to control as many had previously believed.

Initial simulations had suggested that triggering and sustaining the fusion reactions might be too difficult. But “we’ve made enormous steps forward,” says Anne Davies, director of the US Energy Department’s Office of Fusion Energy Science. An International Atomic Energy Agency meeting last month in Portugal generated considerable excitement because experiments with test reactors around the world suggested ITER’s reactor would work as designed.

And what is fusion?

The idea behind fusion is fairly straightforward. Today’s nuclear reactors derive their energy by splitting atoms in a process called fission. Fusion works by combining them – actually the nuclei of two forms of hydrogen known as deuterium and tritium. Fusing nuclei requires more energy than splitting them, but the payoff is larger. A fusion reaction gives off three to four times as much energy as a fission reaction does.

The challenge: For fusion to occur, the surroundings must be torrid. Researchers anticipate their experimental reactor will run at 100 million degrees C – roughly six times as hot as the sun’s core. At these temperatures, atoms and their electrons part company and form a roiling particle soup called a plasma. Such temperatures also give the nuclei of the atoms enough speed to fuse with other nuclei when they hit them. But because the plasma is filled with electrically charged particles, many researchers hold that the only way to keep the plasma bottled up is with magnetic fields.

Scientists are excited:

“The fusion energy program has risen to a new level of scientific understanding,” Davies says. “We’re now measuring and controlling plasmas consistent with computer simulations. This represents an enormous step forward.”