A group of researchers at New Jersey-based LPP Fusion is turning to crowdfunding to demonstrate net power gain from a nuclear fusion reactor. The scientists plan to do this using a technique which is relatively little-known, but which they claim is scientifically sound and only relies on well-established science. Given enough funding, the researchers say they could design a US$500,000, 5 MW reactor that would produce energy for as little as 0.06 cents per kWh, all by the end of the decade.

You'd be excused for doubting that research into fusion power could successfully be crowd-funded. ITER's tokamak, which is being built in the south of France, is requiring a collaboration of seven countries and has seen several delays, with costs now expected to exceed the €10 billion (US$13.7 billion) mark. Barring further difficulties, the ITER project is slated to begin operations in 2027 at the earliest.

According to LPP Fusion chief scientist Eric Lerner, the vast majority of the financial resources have been allocated to ITER's approach to fusion power, while other avenues, such as the one being pursued by his team, have been largely neglected, despite being much cheaper. Using an approach he calls "focus fusion," Lerner says his team can obtain a crucial electrode for $200,000, demonstrate net power gain with $1 million, and solve the final engineering problems, leading to a functioning fusion reactor with just $50 million in funding.

How it works

In a standard nuclear fusion approach, the idea is to capture the plasma and make it stable, which is technically extremely challenging (and expensive). The Focus Fusion approach is not to fight those instabilities, but to instead harness them to concentrate the plasma in a very small area.

The plasma focus device, the heart of the fusion reactor, can be as small as just a few inches in diameter (see above). The device consists of a central hollow cylinder made out of copper, the anode, surrounded by an insulator (in white), and an outer electrode, the cathode, a circle of copper rods. The device is enclosed in a vacuum chamber filled with the fusion fuel and attached to a powerful capacitor bank.

A strong current pulse generates plasma between the anode and the cathode of the plasma focus device (Image: LPP Fusion)

In only a microsecond, the capacitor bank pulses a current of over a million amps from the cathode to the anode. This ionizes the gas, turning it into a plasma. At this point, parallel currents run along each other inside the plasma, generating a magnetic field that forces dense plasma filaments to attract and twist around each other, concentrating the plasma over a small area.

The magnetic fields focus the plasma filaments into a donut-shape plasmoid that is only millimeters across and quickly compressing. When the plasmoid gets dense enough, radiation from the center of the plasmoid starts to escape, and that causes a sudden fall in the magnetic field, accelerating a beam of electrons on one end and a beam of ions on the other end. As they leave, the electrons in the beam interact with the electrons in the plasmoid and heat up the area to over 1.8 billion degrees Celsius, which is enough to get fusion reactions.

Natural instabilities briefly concentrate plasma into a donut-shaped plasmoid (Image: LPP Fusion)

The record temperatures achieved in this way are hot enough for fusing a boron and a hydrogen atom briefly into a carbon nucleus, which immediately breaks apart into three helium atoms and a large amount of energy. Unlike the deuterium and tritium used in other approaches, this reaction is aneutronic, which means the end product is charged particles, and no dangerous radioactive waste. In fact, the end products have a half-life just over 20 minutes, meaning that radiation inside the reactor will be back to background levels after only nine hours.

Moreover, because the end product of the reaction is moving charged particles, those can be converted into electricity directly, which is both more efficient and, according to the researchers, up to 10 times more cost-effective.

The final reactor would harvest electricity directly, for better efficiency and vastly reduced costs (Image: LPP Fusion)

Electricity would be generated in two ways. A good 60 percent would come from the ion beam shooting out of the plasmoid, which would be fed to a metal coil, where the rapidly changing electromagnetic fields would generate a current which is then fed into a capacitor with 80 percent efficiency.

The remaining 40 percent of the electricity would be harvested from the x-ray pulse generated by the reaction, which would be collected by a stack of thousands of extremely thin metal foils that will capture electrons into a fine electric grid.

The impact

A full-sized focus fusion reactor, says Lerner, would cost $500,000, which is much cheaper than a standard nuclear reactor, and would be safe and small enough to fit in a garage or a shipping container. It would provide 5 MW of power, which is enough for about 3,500 homes, for as cheap as 0.06 cents per kWh – a twenty-fold improvement over current costs.

With 20 percent of the world's population having no access to electricity, this technique has the potential to offer cheap, clean and decentralized energy that could be deployed even to remote areas.

According to NASA's Jet Propulsion Lab, which financed part of Focus Fusion's research, a functioning reactor could also double as a rocket engine, allowing us to reach Mars in as little as two weeks. Currently, rockets take six months for the trip in the best-case scenario.

The next step

Lerner and colleagues say they have already achieved two out of the three conditions they need to demonstrate a net energy gain: they have heated the plasma to 1.8 billion degrees and confined it to a tiny area for tens of nanoseconds. The third, remaining condition is to achieve a plasma density 10,000 times higher.

The researchers say they know how to do it, and that they could achieve it by using higher-quality beryllium electrodes, employing heavier gases, and switching from deuterium-tritium to hydrogen-boron as fuel.

If the researchers can raise $200,000 for beryllium electrodes, they say they will be able to show that a commercial fusion reactor is feasible and ready for commercial application by the year 2016. By then, it would be much easier to secure the $50 million needed to solve the remaining engineering problems and build a prototype reactor over the following three or four years.

You can find out more on the Indiegogo campaign set up by the researchers. The video below illustrates how the reactor would be able to harness plasma instabilities to generate energy fusion energy.

Source: Focus Fusion