Nuclear fusion company SHINE has reported the first-ever observations of Cherenkov light during a fusion reaction, visual evidence that a reaction was taking place. This phenomenon is more commonly seen in traditional nuclear fission power plants and produces a pretty, blue-violet light.
The closest analogy to explain this phenomenon is sound. When an object, from the tip of a whip to a supersonic plane, goes faster than the speed of sound, there is a boom. When a particle goes faster than the speed of light in a particular medium, you get Cherenkov light.
To be clear, these particles are not moving faster than the speed of light in a vacuum and the fastest possible speed in the universe. But light is about 25 percent slower in water compared to in a vacuum, so, with the right reaction, you can accelerate particles to more than 225,000 kilometers (139,800 miles) per second. In this case, the particles are neutrons being produced in a fusion reaction.
“Normally, to see this with the naked eye, you’d need to be looking at nuclear fission reactor cores or used nuclear fission fuel," Greg Piefer, founder and CEO of SHINE, told IFLScience. "It’s significant because we're able to show steady-state fusion rates at much higher levels than demonstrated previously. We believe this is the first time that a fusion reaction has generated visible Cherenkov radiation.”
SHINE's fusion system uses two special types of hydrogen atoms for their fusion setup: deuterium and tritium. While most hydrogen in the universe has a nucleus made of a single solitary proton, deuterium has a neutron and a proton, and tritium has two neutrons and a proton. The company employs a deuteron beam (just the nucleus of the deuterium) to hit a tritium target at high speed.
“The Cherenkov radiation effect produced here was bright enough to be visible, which means there’s a lot of fusion happening, about 50 trillion fusions per second. At a billion fusions per second, you might have measurable Cherenkov radiation but not visible amounts,” said Gerald Kulcinski, Grainger Professor of Nuclear Engineering-Emeritus and Director of Fusion Technology-Emeritus at the University of Wisconsin-Madison, said in a statement.
“These results are powerful evidence of nuclear processes at play and further proof that fusion can produce neutrons on par with some reactors.”
The approach is currently producing a very low output. The goal of SHINE is to demonstrate the feasibility and scalability of nuclear fusion. At the same time, deuteron beams can be used to produce medically useful radioisotopes, something that SHINE is also involved in.
