Update on General Fusion

General Fusion is nearing significant milestones. General Fusion’s Approach is Magnetized target fusion (MTF). Magnetized target fusion is a hybrid between magnetic fusion and inertial confinement fusion. In MTF, a compact toroid, or donut-shaped magnetized plasma, is compressed mechanically by an imploding conductive shell, heating the plasma to fusion conditions.

General Fusion has a full-scale prototype [of the injectors and other subsystems], twin plasma injectors resembling five-metre-long cones, each attached to opposite ends of a three-metre-diameter sphere, would pulse a few milligrams of hydrogen gas, heat it until it becomes a plasma, and inject it into a vortex of swirling liquid metal. Electricity circulating in the plasma would create magnetic fields that bind the plasma together and confine the heat.

From there, an array of as many as 300 huge pistons attached to the sphere’s shell would act like synchronized jackhammers, ramming it at 200 km/hr. This would send shockwaves into the very centre of the chamber, compressing the hydrogen isotopes to 100 million degrees celsius — hot enough for fusion to occur, and good enough to generate clean electricity from steam turbines.

General Fusion reached its milestones on the piston timing about two years ago. Technicians are now perfecting functionality of the plasma injectors.

The nearly 200 capacitors that send 10-gigawatt bursts into General Fusion’s machine were “recycled” from an old laser fusion experiment in Los Alamos, California.

Here is 2013 paper on the progress on the driver timing and the injector work.

General Fusion, which shares investors with D-Wave, is about two to three years out from creating its own power plant. Today, the pistons work well, and the plasma is hot enough and dense enough. Within the last month, the gas donut has started lasting long enough for the system to work, so now the company is turning its focus to compression and timing, according to Michael Delage, VP of strategy and corporate development.

General Fusion thinks it can provide power at a cost of seven cents per kilowatt hour, comparable to the cost of coal.

General fusion also wants to heat the spheromak to 500 eV before injection. They have reached 200 eV, while they would want to reach 500 eV and expect actually to exceed 600 eV.

31 page presentation on General Fusion from mid-2013

In the TEDX talk of 2014 – there is the offhand mention that the plasma lifttime issue of getting to 100 microseconds had good progress

The Plan from 2012

In a 2014 Nature paper, there is the statement that the General Fusion “beefier” prototype will be built perhaps by the end of 2016.

General Fusion has demonstrated the idea with a small-scale device, using pistons driven by explosives, and has raised about $50 million from venture capitalists and the Canadian government. If the company can win another $25 million or so, Laberge says, it will build a beefier implosion system that can compress the plasma to the levels needed for fusion — perhaps within the next two years.

Not sure if the beefier prototype would be the net gain prototype since previously that was $80-100 million.

General Fusion is developing full scale subsystems to demonstrate that they can meet their performance targets. This includes full scale plasma injectors and acoustic drivers, and liquid metal vortex compression tests. Every step is matched with simulation to guide ongoing development work.