Burner Mirror Coils
The mirror coils shape the axial field, gentle in the central cell and intense at the plugs, to confine the plasma.
Sculpting the axial field
A tandem mirror is defined by its magnetic field profile along the axis: moderate in the central cell, then rising steeply to a peak at each plug throat, then falling in the expander. The mirror coils are the ring magnets strung along the axis that produce this profile. Their spacing and current set where the field is weak, where it peaks, and how sharply it changes.
The coil families
- Central-cell coils produce a long region of moderate, fairly uniform field.
- Plug coils produce the intense fields, up to 26.49 T at the plug and 17 T at the throat.
- Expander coils let the field flare down beyond the throat.
- All are wound from high-temperature REBCO superconductor to reach the required fields.
The mirror ratio
The single most important number the coils set is the mirror ratio: the peak plug field divided by the central-cell field. A larger ratio reflects more particles and confines better, which is why the plug coils are pushed to such extreme fields. The whole coil layout is an exercise in achieving a high mirror ratio without the field changing so abruptly that it drives instabilities.
In the model
The mirror coils are selectable individually or as families along the axis. The axial cutaway can plot the field magnitude against position so you can see the moderate central plateau rising to the 26.49 T plug peak. This is the clearest way to read how coil placement becomes confinement.
Shared magnet technology
The coils use the same REBCO conductor as Hyperion's magnets. See the REBCO magnet model and the plug throats the plug coils produce.