Princeton Plasma Physics Laboratory (PPPL) scientists have developed a new computer code for designing more advanced stellarators.
A stellarator is a twisting magnetic coil device that has to be engineered precisely to prevent heat from escaping the plasma core where it stokes the fusion reactions.
Fusion combines light elements in the form of plasma – the hot, charged state of matter composed of free electrons and atomic nuclei – and generates massive amounts of energy in the sun and stars.
Scientists have been aiming to replicate fusion in devices on Earth for a virtually inexhaustible supply of safe and clean power to generate electricity.
And this is where the stellarators come into the picture.
PPPL’s new code – XGC-S – could help design more advanced stellarators that confine the essential heat more effectively.
“The main result of our research is that we can use the code to simulate both the early, or linear, and turbulent plasma behavior in stellarators,” notes lead author and PPPL physicist Michael Cole.
“This means that we can start to determine which stellarator shape contains heat best and most efficiently maintains conditions for fusion.”
The PPPL team simulated the behavior of plasma inside fusion machines called ‘Tokamaks’ that look like a donut, but with pinches and deformations that make the device more efficient.
They then used the XGC-S for modeling turbulence in these fusion facilities.
These modifications also allowed the new XGC-S code to model plasmas in the geometrically more complicated stellarators.
The simulations showed that a type of disturbance limited to a small area can become complex and expand to fill a larger space within the plasma.
The results showed that XGC-S could simulate this type of stellarator plasma more accurately than what was previously possible.
Moreover, the code can calculate the turbulence in stellarators all the way from the plasma core to the edge, providing a more complete picture of the plasma’s behavior.
“Turbulence is one of the primary mechanisms causing heat to leak out of fusion plasmas,” says Cole.
“Because stellarators can be built in a greater variety of shapes than tokamaks, we might be able to find shapes that control turbulence better than tokamaks do.”
The scientists are now planning to modify the XGC-S even further to produce a more clearer view of how turbulence causes heat leakage.
Image and content: Swansea University/PPPL