Established physics
Neutrons carry most of the D–T fusion energy.
Deuterium–tritium fusion produces a helium nucleus (an alpha particle) and a neutron. About one fifth of the energy goes to the alpha particle and the rest to the neutron. This is textbook physics, not an assumption.
A magnetic nozzle can only steer charged particles. The neutron has no charge and passes straight through the field. So if only charged products feed the exhaust, the engine uses just a small part of the fusion energy.
The model question
Recovering neutron energy in the propellant.
In the SPRINT concept the target is surrounded by propellant in the form of a plasma liner. Some neutrons are absorbed there and heat it, and that heated, charged material leaves through the nozzle. The model has to show what share of the neutron energy the liner can actually capture and pass on to the exhaust.
Whatever does not reach the exhaust does not vanish: neutrons that miss the liner heat the shield and coils, and radiation goes to the radiators. The model must account for every one of these terms.
What we test
Parameters that determine the energy balance.
| Parameter | Status | What we test |
|---|---|---|
| Alpha-particle energy share | known | A tabulated value for D–T; not adjustable |
| Fusion yield per pulse | under study | Whether it is realistic at the given compression; NIF results are the benchmark |
| Pulse rate | under study | Whether target delivery and system recharge can keep up |
| Neutron capture by the propellant | key question | How much neutron energy the liner absorbs and how much goes to the shield |
| Magnetic nozzle efficiency | under study | What share of plasma energy becomes directed flow |