Energy Department fusion discovery could allow physicists to tame volatile plasma – report

Researchers at the U.S. Department of Energy’s Princeton Plasma Physics Laboratory (PPPL) have developed a new strategy for seeking to generate electricity from fusion: combining two existing plasma management methods to achieve greater overall flexibility.

PPPL 團隊的新雙方法將電子迴旋電流驅動(ECCD) 方法與共振磁擾動(RMP) 方法結合在一起，標誌著首次透過模擬展示它們如何一起使用，從而有助於在聚變反應期間更好地控制plasma.

Simply put, fusion creates energy by replicating the natural processes that occur on the surface of the sun. This is accomplished by merging two light nuclei to form a heavier nucleus, a process that releases energy because although the resulting nucleus is heavier, its total mass is still less than the mass of the two original nuclei that merged.

However, generating energy in this way is difficult to replicate on Earth and requires the creation and control of extremely hot gases called plasmas, which can be controlled using electric and magnetic fields because the electrons and ions they possess carry electrical charges.

Qiming Hu, a PPPL research physicist at General Atomics’ DIII-D National Fusion Facility, said the team’s dual approach is a novel one, and while all the details are still being worked out, he and his team are very excited about what he and his team are doing. This new approach, described in a new paper written by colleagues, is about to become a reality.

The full functionality is still a work in progress, but our paper does a good job of improving our understanding of the potential benefits, said Hu, lead author of the team’s new paper, noting that the process they outline has also been proven experimentally.

Until fusion can reliably produce electricity, scientists are working to find ways to reduce the occurrence of particle bursts produced by the plasma, known as edge localized modes (ELMs).

These bursts periodically release a little bit of stress because it’s just too much. But Hu said in a statement that these outbreaks could be dangerous.

The device Hu and his colleagues used at PPPL’s ​​DIII-D National Fusion Facility is a tokamak, which relies on magnetic fields to confine fusion plasma in a donut shape.

Researchers are working hard to find ways to prevent ELM bursts from occurring, as they can interrupt fusion reactions, causing them to end prematurely or even cause damage to the tokamak device.

Alessandro Bortolon, principal research physicist at PPPL and one of the co-authors of the new paper, said the best method the team has found so far is to use resonant magnetic perturbation (RMP) to generate additional magnetic fields to help suppress volatile plasmas.

The tokamak main magnetic field wraps around the outer edge of the toroidal plasma and passes through the central hole, applied by the device, while the additional magnetic field generated by the RMP passes directly through the plasma, together forming an elliptical or circular magnetic island in most cases , this is not what nuclear fusion scientists want to see.

Typically, islands in plasma are really, really bad, said Bertolon. If the island is too big, the plasma itself will break up.

That’s not to say they can’t help under the right conditions. Past experiments have shown that creating these magnetic islands can be helpful, although it requires generating a powerful enough RMP to create them.

Enter the electron cyclotron current driver (ECCD), which helps by injecting a microwave beam at the edge of the plasma, which completely reduces the current required to generate RPM sufficient to create magnetic islands.

Using this process, the PPPL team was able to create islands of just the right size to ensure maximum plasma edge stability. This is possible because the RMP functions like a switch that turns the island on, while the ECCD functions like a dimmer switch, allowing the size of the island to be adjusted to produce a plasma of manageable size.

Additionally, the team broke with traditional approaches by adding ECCD to the edge of the plasma rather than its core, as is most common in such experiments. One reason this is usually avoided is the potential risk microwaves could pose to components in the tokamak, although Hu and his team say they have found a way to do it safely.

“We have proven that this is possible, and we have also demonstrated the flexibility of this approach,” Hu Jintao said in a statement. This could open up new avenues for designing future devices.

In their theoretical model, Hu says, the ECD is in the same direction as the current in the plasma, leading to smaller island widths and increased pedestal pressure. Nonsense, applying ECCD in the opposite direction will produce the opposite result, increasing island width, decreasing pedestal pressure or promoting island opening.

Overall, reducing the amount of electrical current typically required to produce RMPs could pave the way for more cost-effective fusion energy production and may also help create commercial-scale fusion devices.

The PPPL team’s new paper details their findings, published in the journal Nuclear Fusion.

Micah Hanks is the editor-in-chief and co-founder of The Report. You can contact him via email:micah@thedebrief.org.Follow his workmicahhanks.comOn X:@michahanks.