https://www.sciencedaily.com/releases/2020/06/200630193209.htm > "Conventional models explain most instances of the sawtooth crashes, but there is a tenacious subset of observations that we have never been able to explain," said PPPL physicist Christopher Smiet, lead author of a paper reporting the results in Nuclear Fusion. "Explaining those unusual occurrences would fill a gap in understanding the sawtooth phenomenon that has existed for almost 40 years." > Fusion combines light elements in the form of plasma -- the hot, charged state of matter composed of free electrons and atomic nuclei -- and in the process generates massive amounts of energy in the sun and stars. Scientists are seeking to replicate fusion in devices on Earth for a virtually inexhaustible supply of safe and clean power to generate electricity.