INNOVATION January-February 2012

Capacitor Bank

Plasma Injector

This graphic shows the plasma in the center of the vortex with the shockwave created by pneumatic pistons.

Pneumatic Pistons

Plasma instability has produced disappointing results for both fusion methods. Also, electromagnets, electrical coils and lasers require substantial power to operate, and the amount of energy produced so far by fusion has been less than break-even. Current Efforts Underway Theoretically a large-scale magnetic confinement machine would be more successful than a smaller machine. China, Europe, India, Japan, the Russian Federation, South Korea, and the US have joined forces on ITER, a 17 m diameter tokamak under construction in France. ITER will begin operations in 2019, and cost US $22 billion. It is expected to produce more than net energy by 2021, and ITER management is planning construction of a demonstration fusion power plant further in the future. Research into inertial confinement continues at the US$4 billion National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in California. The NIF hopes to achieve break-even this year, which would be a significant milestone. However, power production at Livermore will require a different machine, planned for the 2020s. A newer method is magnetized target fusion, which combines elements of magnetized and inertial approaches. This process is being studied by Los Alamos; the US Air Force Research Laboratory; and Burnaby-based company, General Fusion. Magnetized target fusion combines the approaches of magnetic and inertial methods. Fuel is heated into plasma in a vacuum, and confined in magnetic fields. Then the plasma is compressed to increase density and temperature until it fuses reliably. Like inertial confinement, this process produces pulses of energy, which can be repeated. Making Fusion a Reality General Fusion is a recent startup led by President and Chief Technology Officer Dr Michel Laberge and Chief Executive Officer Doug Richardson, The company has raised over $30 million in private venture capital and Canadian government foundation funding to produce a prototype

If it proves feasible, the payoff will be enormous. Deuterium and tritium are the easiest isotopes to fuse. Deuterium is abundant in water, while tritium can be bred from lithium by the fusion process itself. Gram for gram, such fusion fuel releases a million times the energy of chemical fuels, so little fuel is needed. The reaction can be easily halted, so reactor meltdowns are unlikely, and fusion does not produce long-lived radioactive waste products. The first step in achieving fusion power has been to create plasma in a vacuum. Fuel, usually deuterium and tritium, needs to be heated evenly to at least 50 million degrees Celsius—much hotter than the core of the Sun—in pursuit of a more rapid reaction. Plasma tends to expand, so it must be confined and compressed for sustained fusion to occur. Maintaining the necessary temperatures and pressures has been a major challenge. The first method invented to contain plasma was magnetic confinement. No physical material can hold the super hot ionized gas, but magnetic fields can keep it suspended. A popular form of fusion vessel is the toroidal (doughnut-shaped) tokamak, devised in the USSR during the 1950s. The other major method is inertial confinement. Powerful laser beams are fired at a frozen plastic pellet of fuel from many directions; the lasers vaporize the plastic shell causing an implosion that compresses the fuel to fusion temperatures and densities. Above: Model of the fusion demonstrator. Opposite: CTO Michel Laberge works at the back of a plasma injector which heats deuterium-tritium gas in a toroidal magnetic field and compresses it through a conical chamber using a high- voltage electrical discharge.

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