Burnaby, British Columbia-based General Fusion has announced that it has achieved first plasma at its Lawson Machine 26 (LM26) experimental fusion reactor. The reactor’s start-up marks the start of a 96-week experiment that is designed to reach the so-called break-even point, the point at which the energy released by fusion equals the energy needed to start and maintain the reaction.
Image source: General Fusion
It took 16 months to build the LM26 demonstrator. It is not the first or last prototype reactor before a commercial fusion plant is built. General Fusion has been working toward this goal for more than 20 years, since its founding in 2002, and remains a long way from the ultimate goal of creating a fusion plant with at least zero yield. The first plasma at LM26 gives hope for a successful experiment. If all goes according to plan, the breakeven point will be reached in 2026.
It should be noted that the breakeven point can be scientific and commercial. In the first case, only the energy spent directly on igniting the thermonuclear fuel is taken into account. This point was first achieved at the National Ignition Facility (NIF) in the United States. In the case of a commercial breakeven point, the energy of the entire system is taken into account, which significantly exceeds the energy needed just to start the thermonuclear reaction. No one in the world has yet managed to achieve this.
The LM26 setup partially uses the method used in NIF. In the American inertial ignition system of deuterium-tritium fuel, pressure is created by a multitude of focused laser beams. In the case of magnetized target fusion (MTF) General Fusion, pressure on the fuel is created simultaneously by a magnetic field and physical compression of the jacket inside the reactor working chamber. The magnetic field at the moment of the spark compresses the plasma formed in the reactor, and additional pressure is created by a shock wave from the compressing jacket. Interestingly, the jacket is compressed by the action of steam pistons – real steampunk.
In the commercial General Fusion reactor, the jacket will be made of liquid metal—an alloy of lithium and lead. It will perform several functions at once: it will trap the neutrons produced during nuclear fusion, serve as a protective shield against radiation, and also act as a coolant, transferring heat for subsequent energy generation. In the LM26 demonstration facility, the jacket is a shell of solid lithium, which is compressed by electromagnets.
The idea of the MTF reactor was proposed by American scientists back in the 1970s. However, they failed to achieve a stable thermonuclear reaction in it. General Fusion believes that the problem was in the insufficiently precise control of the pistons that provide compression of the shell and plasma. Modern computing systems are capable of solving such problems, and the company promises to prove this in the coming year.