In a burning plasma, keeping the high-energy ions produced by fusion contained is key to generating energy. There are large amounts of electromagnetic waves in these fusion plasmas that can squeeze high-energy ions out of the plasma. This reduces the heating of the plasma by the fusion reaction products and ends the burning state of the plasma. New observations from the DIII-D National Fusion Facility provide important insights into high-energy ions in fusion plasmas, which are critical for the development of fusion power plants and the understanding of space plasmas, with implications for satellite technology.
Recent measurements at the DIII-D National Fusion Facility provide the first direct observations of the spatial and energetic movement of high-energy ions in a tokamak. The researchers combined these measurements with advanced computer models of electromagnetic waves and their interactions with energetic ions. These results deepen our understanding of the interaction between plasma waves and high-energy ions in fusion plasmas.
Plasma physics and fusion research are moving from experimental facilities to demonstration power plant designs. To make this transition successful, researchers need accurate simulations and other tools to predict the performance of power plant designs. Most current facilities are unable to generate combustion plasma. However, researchers understand much of the relevant physics and are developing simulation tools to reproduce the observed experimental behavior.
The current study provides new measurements of high-energy ion currents in the DIII-D tokamak. This will accelerate the development of models that can account for the dynamics of all relevant wave-ion interactions. Phase space engineering can also be applied after a deeper understanding. Researchers can use this process to design new fusion plasmas based on predicted ideal interactions between waves and ions. Notably, these interactions can also damage satellites, so this research could help improve satellite reliability.
Researchers at the DIII-D National Fusion Facility, a Department of Energy user facility, made the first measurements using a new diagnostic system, the Imaging Neutral Particle Analyzer (INPA), to observe the flow of high-energy ions in a tokamak. After years of conception, design and construction, INPA now has the ability to observe this behavior for the first time.
After high-energy ions are injected into the tokamak by a neutral beam, they interact with electromagnetic plasma waves and flow with energy and position in the tokamak. The simulations reproduced the observed behavior, demonstrating the accuracy of the first-principles model in describing the underlying physics. Improving our understanding of these wave-particle interactions has important implications both for designing nuclear fusion power plants and for understanding the behavior of plasmas observed in outer space.
INPA measures the energy of high-energy ions injected by a neutral beam that are greater than the energy of the background plasma from the hot plasma core to the edge of the cold plasma. These experiments, combined with advanced high-performance computing simulations that simulate the electromagnetic spectrum and interactions with energetic ions, provide the most detailed understanding of the interaction between plasma waves and energetic ions in fusion plasmas.
This increased understanding also enables researchers to apply phase space engineering, which is the design of new fusion plasma schemes based on predicted ideal interactions between waves and ions. These types of interactions occur in outer space. For example, electromagnetic ion cyclotron (EMIC) waves cause electrons to flow through space and energy.
In some cases, the electrons are accelerated, causing satellites to malfunction. A deeper understanding of the wave-particle resonance interaction process through fusion plasma research will help simulate outer space plasma, thereby improving the reliability of future satellite missions.
Compiled source: ScitechDaily