Advancements in Fusion Research: Fresh Perspectives on Energetic Ion Flow

The DIII-D National Fusion Facility has recently conducted research that present key findings about energetic ions present in fusion plasmas, which are critical to maintaining a state of burning plasma. These findings significantly advance our understanding and could pave the way for the development of fusion power plants. They could also enhance our knowledge about plasma behaviors in space, potentially increasing the reliability of satellites. Credit: SciTechDaily.com

These new findings from the DIII-D National Fusion Facility provide valuable insights into energetic ions in fusion plasmas. This information is critical to the development of fusion power and to our understanding of plasma in space and its implications on satellite technology.

In a plasma state, confinement of fusion-produced energetic ions is vital to generate energy. Fusion plasmas house a broad range of electromagnetic waves that can force energetic ions out of the plasma. This consequently lowers the plasma's heat, generated from fusion reaction products, ending the state of burning plasma.

Latest measurements from the DIII-D National Fusion Facility are the first to directly observe energetic ions moving through space within a tokamak. Researchers have melded these findings with sophisticated computer models of electromagnetic waves and their interaction with energetic ions. This gives us a better understanding of the relationship between plasma waves and energetic ions in fusion plasmas.

Fusion and plasma physics research are transitioning from experimental facilities to the development of demonstration power plant designs. To make this transition successful, researchers require precise simulations and other predictive tools to assess the performance of power plant designs. Most existing facilities do not generate burning plasmas, but researchers are developing simulations to reproduce experimental behavior.

The present study carried out new measurements of the flow of energetic ions in the DIII-D tokamak. This research will expedite the development of models that incorporate all pertinent wave-ion interaction dynamics.

Researchers can now use this comprehensive understanding to apply phase-space engineering. This process lets researchers create designs for new fusion plasma scenarios based on anticipated ideal wave-ion interactions. However, these interactions can disrupt satellites, so this research should improve the reliability of satellites as well.

The flow of energetic ions in DIII-D plasmas was both measured and simulated. Starting from the injected energies of neutral beams, these ions move around in space and energy due to electromagnetic wave interactions. Credit: X.D. Du, General Atomics

Scientists at the DIII-D National Fusion Facility, a Department of Energy user facility, were the first to apply measurements from a novel diagnostic tool, the Imaging Neutral Particle Analyzer (INPA), in observing the flow of tokamak's energetic ions. The INPA, a result of multi-year efforts to conceive, design, and build, provided the first-ever capability to observe this behavior.

Once injected into the tokamak by neutral beams, energetic ions interact with electromagnetic plasma waves and move around in space and energy inside the tokamak. Simulations validate this observed behavior, thus attesting to the accuracy of first-principle models in explaining the fundamentals of physics. Greater understanding of these wave-particle interactions is essential to the design of future fusion power plants and understanding plasmas behavior in outer space.

The INPA can assess the energy of neutral beam-injected energetic ions, which exhibit energies higher than the background plasma. It can measure it across time and spatial position from the hot plasma core to the cold plasma edge, where the ions can be lost. Combined with sophisticated high-performance computing simulations modeling both the variety of electromagnetic waves and interactions with energetic ions, this experiment offers the most detailed understanding of the relationship between plasma waves and energetic atoms in fusion plasmas to date.

This understanding also allows scientists to apply phase-space engineering for designing new fusion plasma scenarios based on anticipated ideal wave-ion interactions. These interactions also occur in space, with electromagnetic ion cyclotron (EMIC) waves for instance, causing electrons to move in space and energy.

There have been times when electrons were speeded up to a degree that resulted in satellite malfunctions. This improved understanding of wave-particle resonant interaction processes through fusion plasma studies can contribute to simulations of outer space plasma which could enhance the reliability of future satellite missions.