American Scientists Are About to Start Shooting Plasma Guns in a Bid to Achieve Controlled Nuclear Fusion

Scientists at the Los Alamos National Laboratory in New Mexico are about to start experiments with "plasma guns" in the hope of achieving controlled nuclear fusion—a source of clean and near limitless energy.

Nuclear fusion is the way the sun generates power. It involves two small, lighter nuclei joining together to create one heavy nucleus. When they join together, energy is released. However, achieving this in a stable state, meaning the energy can be harnessed, is extremely difficult. High pressures and temperatures of around 150 million degrees Celsius are required.

Generally scientists have been focused on producing fusion energy in two types of devices— tokamaks and stellarators. These are donut-shaped devices that use magnets to confine the plasma—a state of matter—in which the fusion reactions can take place. The problem with these devices is stability. Like reactions on the sun, fusion can produce flares, which can damage their walls. Researchers are currently working on suspending plasma in a stable state to the point where energy can be harnessed at an economic level.

However, researchers at Los Alamos are taking a different approach. They have begun assembly of the Plasma Liner Experiment (PLX), which involves installing 36 plasma guns around a spherical chamber. These guns will then fire "supersonic jets of ionized gas" inwards towards a gas target that will be fusion fuel, a statement from the American Physical Society said.

The first step will be to install 18 of the 36 guns so they can begin testing the technique. The machine uses both magnetic confinement (like tokamaks) and inertial confinement, where powerful beams of laser are used to compress and heat isotopes to the point of fusion. By using both techniques, the team hopes to achieve stable nuclear fusion that may be cheaper and less complicated than other methods.

"Plasma guns are pulsed electrical devices that can accelerate matter to high velocities, and can do so very efficiently in comparison to [for example] laser-driven approaches," Samuel Langendorf, who is leading the assembly of PLX, told Newsweek.

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The Plasma Liner Experiment at the Los Alamos National Laboratory. So far 18 plasma guns have been assembled and another 18 will be added early next year. Los Alamos National Laboratory

The PLX will magnetize the plasma to help prevent the loss of particles and thermal energy. But like inertial confinement, it will rapidly compress and heat the fuel to generate conditions for nuclear fusion with the plasma guns. The guns are fired by driving a high electrical current between the gun electrodes. This, Langendorf said, "creates an electromagnetic force that launches the plasma out of the muzzle of the gun."

"The plan is that a spherical array of plasma guns, all firing towards the center, form a spherically imploding shell or 'liner' of plasma," he explained. "This liner than acts a heavy and extremely fast piston, to compress fusion fuel in the center to the very high temperatures and pressures needed for fusion to occur.

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Supersonic jets fired from seven guns collide. Researchers hope their technique will lead to stable nuclear fusion. Los Alamos National Laboratory

"One of the most promising aspects to this approach is that if successful, all of the experimental equipment/hardware is separated and physically spaced away from the center of the chamber—where the fusion would occur—by several meters of 'standoff' distance. This means you don't destroy any expensive parts of your system on a given shot, and the heat and particle fluxes to your equipment can be made much lower and more manageable, which in turn could enable the repetitive operation needed for a power plant."

The team is planning to test the 18 guns this year and to install the other 18 early in 2020. They are aiming to start testing all 36 by the end of next year. Langendorf said they are hoping to show that the liner formation works and can be used to compress and heat fusion plasmas.

"One thing that could go wrong is that the plasma jet merging process may give rise to too many non-uniformities in the liner, which can lead to instabilities and reduced effectiveness of target compression," he added. "One of the main goals of this experiment is to get some data to benchmark computer simulations of these types of experiments, so we can understand the merging process and how it might scale towards a breakeven-class fusion machine."