Energetic Particle Codes
Energetic particle codes follow fast ions from heating and fusion reactions through their slowing-down, tracking losses, redistribution, and wall loads.
The fast-ion population
Neutral beams, radio-frequency heating, and fusion reactions produce ions with energies far above the thermal bulk. These energetic particles carry heating power and current and can drive instabilities. Dedicated codes follow their orbits and their slow collisional relaxation onto the background, answering where their energy is deposited and whether any are lost to the wall.
The tools range from orbit-following Monte Carlo codes, which push individual guiding centers with pitch-angle and energy scattering, to kinetic solvers that evolve the fast-ion distribution in phase space.
Orbit topology and losses
Fast ions execute passing, trapped, and stagnation orbits whose radial excursions can be large, especially at low aspect ratio. Codes classify orbits, identify loss regions in phase space, and compute the flux of escaping ions to specific wall locations, which drives localized heat and damage concerns.
Coupling to instabilities
Energetic-particle transport is often anomalous because Alfven eigenmodes, analyzed with kinetic-MHD codes, redistribute fast ions. Advanced workflows couple the orbit-following code to the mode structure to model resonant transport rather than assuming classical slowing-down alone.
Design relevance
For the Aegis and MetroVolt burner, a D-3He tandem-mirror generator, energetic-ion behavior is central: the fuel ions and reaction products are fast, and their confinement in the 26.49 T plug governs performance and the direct-energy-conversion scheme. For the Hyperion breeder, alpha and beam confinement bears on heating and wall loading. All results are simulation studies.
- Follows fast ions from heating and fusion
- Orbit-following Monte Carlo or kinetic solvers
- Computes losses and wall-load hot spots
- Couples to Alfven-mode-driven transport