Research in nuclear fusion depends on understanding super-heated plasmas. A new system of classifying magnetized plasma has led to the discovery of ten unknown topological phases. A better understanding of these phases and the transitions between them could assist physicists in the development of practical commercial fusion reactors. The transitions between these new phases support waves at the intersection of plasma surfaces.
These exotic excitations could expand the potential practical uses of magnetized plasmas. Yichen Fu is a physicist at the Princeton Plasma Physics Laboratory (PPPL). He said, “These findings could lead to possible applications of these exotic excitations in space and laboratory plasmas. The next step is to explore what these excitations could do and how they might be utilized.”
Recent research has begun to focus on the topological properties of plasma which means studying the shapes of the waves inside the plasma. The topological phases in cold magnetized plasma and transitions between them have not been thoroughly explored. This research is important because it will help scientists understand how plasma interacts with itself.
Fu and his colleague, PPPL physicist Hong Qin, sought to describe mathematically the topological phases of a cold plasma in a uniform magnetic field. They discovered ten different novel plasma phases separated by edge modes. These modes are the boundary between two topological different regions within the plasma. Numerical studies have verified the findings of the pair of physicists.
Qin said, “The discovery of the 10 phases in plasma marks a primary development in plasma physics. The first and foremost step in any scientific endeavor is to classify the objects under investigation. Any new classification scheme will lead to improvement in our theoretical understanding and subsequent advances in technology.”
The paper from Fu and Qin does not speculate about what those advances might be. However, there are some interesting possibilities. Plasma is often referred to as the fourth state of matter. It is a gas in which electrons have been stripped from the atoms. This forms an ionized material. Plasmas are abundant in space. It is the state of matter that is found in stars and is a key to potential plasma technology.
Deep in their cores, stars fuse nuclei to create heavier elements. This process generates a vast amount of energy. Researchers have been working on the creation of plasma fusion on Earth. Supporters of this research claim that fusion reactors could provide clean and cheap energy.
Creating fusion on Earth has proven to be extremely difficult. Scientists need to be able to maintain a stable plasma as temperatures hotter than the Sun for long enough to generate and extract energy. There are many technological challenges and researchers are still far from their goal of commercial fusion reactors. A better understanding of the behavior of plasmas can bring that goal closer.
Fu said, “The most important progress in the paper is looking at plasma based on its topological properties and identifying its topological phases. Based on these phases we identify the necessary and sufficient condition[s] for the excitations of these localized waves. As for how this progress can be applied to facilitate fusion energy research, we have to find out.”