The mysterious and ghostly "whistle wave" usually produced by lightning can protect the nuclear fusion reactor from the destruction of runaway electrons. New research shows that,
These whistler waves are found in the ionosphere above the ground, which is a layer of the earth's atmosphere, about 50 to 600 miles (80 to 1000 km) from the earth's surface. When the electromagnetic pulse generated by lightning propagates between the northern and southern hemispheres, these ghostly whistle waves will be formed. When these waves pass through the earth, their frequency will change. When these optical signals are converted into audio signals, they sound like whistles.
According to the latest research published in the journal Physical Review Letters on April 1 1, these whistle waves have been found in the hot plasma in the Tokamak (a ring machine with nuclear fusion reaction).
Whistle can scatter and hinder high-speed electrons, so it can provide a new way to prevent runaway electrons from destroying the interior of the tokamak. In the nuclear fusion reaction
Nuclear fusion can provide energy for the sun and stars. Atoms collide and fuse into larger atoms, releasing energy at the same time. For decades, researchers have been trying to use the fusion energy on the earth and the powerful magnetic field inside the tokamak device to surround the annular cloud formed by hot plasma, which is a strange material phase composed of charged gas.
Inside the tokamak device, the electric field can push the electrons faster and faster. But when these high-speed electrons fly in plasma, they can't slow down. Usually, an object moving in a gas or liquid will feel resistance that increases with speed. For example, the faster you drive, the greater the wind resistance. However, in plasma, the resistance decreases with the decrease of speed, which accelerates the electrons to near the speed of light, thus damaging the tokamak. Don Spock, a physicist at Oak Ridge National Laboratory in Tennessee and a co-author of the new study, said:
Some researchers have developed some techniques to reduce out of control. They can use artificial intelligence algorithms to monitor and adjust the density of plasma to prevent electrons from accelerating too fast. If escape still exists, they can inject frozen neon particles into the plasma, thus increasing the plasma density and slowing down the runaway electrons.
But whistle waves may be another way to control runaway electrons. "Ideally, we want to avoid interference and evasion," Span said, but if they happen, we want to have all kinds of tools to deal with them.
For the first time, Spong's team stopped the escaping electrons in the Tokamak at the DIII-D National Fusion Facility in San Diego.
He explained that plasma is like a jelly with multiple vibration modes. If some out-of-control electrons only have the right speed, they will excite one of the modes and trigger a whistle wave-similar to driving an old car at the right speed that will cause the dashboard to vibrate.
What we want to do is reverse engineering and put these waves outside (plasma) to disperse the fugitives, Spencer said.
By better understanding how fugitives whistle, researchers hope that they can reverse this process-using external antennas to generate whistles can disperse electrons and prevent them from becoming too fast.
Researchers need to further explore the relationship between fugitives and whistling. For example, Spong said that by identifying which frequencies and wavelengths can be suppressed to the greatest extent.