Burner Expander
The expander is the flaring region beyond each plug where the escaping plasma spreads out along widening field lines.
Letting the plasma spread
No mirror is perfect; some plasma always escapes past the plug throats. The expander is the region beyond each throat where the magnetic field deliberately weakens and the field lines flare apart. As the field drops, the escaping plasma spreads across a much larger area, which is exactly what the next stage needs.
Why spread the plasma
- Concentrated plasma leaving the throat would deliver a punishing heat load onto a small area.
- Spreading it across a wide expander surface reduces the power density to manageable levels.
- The expansion also sorts the particle flow in a way that prepares it for direct energy conversion.
- It provides room to handle the exhaust without eroding a small target.
Magnetic expansion
Because charged particles follow field lines, widening the field lines widens the plasma stream. The expander is essentially a magnetic nozzle run in reverse: instead of focusing the flow, it dilutes it. The degree of expansion is a design parameter, set by how much the field is allowed to fall from the throat value of 17 T out to the converter.
In the model
The expander is the flaring section between each plug throat and its end assembly. In the axial cutaway the field lines can be shown fanning outward through it, and the growing cross-section is visible directly. Selecting it reports the expansion and the resulting drop in power density onto the converter.
What comes next
The spread-out plasma flows into the converter. See the direct-energy converter it feeds and the plug throats it follows.