Ultra-High-Field MHD Conversion
Magnetohydrodynamic conversion draws current directly from an electrically conducting plasma flow as it crosses an intense magnetic field.
A generator with no moving parts
Magnetohydrodynamic (MHD) conversion applies Faraday's law to a flowing plasma. A conducting fluid moving with velocity v across a magnetic field B experiences a force on its charges, v×B, which drives a current transverse to both. Place electrodes on the flow's sides and that current flows into an external load. There is no turbine and no rotor — the moving conductor is the plasma itself.
Why ultra-high field
The power density and voltage of an MHD generator scale strongly with the magnetic field. The burner is a tandem mirror built around superconducting magnets reaching 26.49 T at the plug and 17 T at the throat, so it already carries the ultra-high-field capability that makes MHD conversion attractive. A strong field means more v×B per unit flow, so a compact channel can convert a large fraction of the ordered flow energy.
What MHD converts best
- The bulk, ordered flow of the expanding plasma leaving the mirror — not individual high-energy ions.
- Energy that is thermal-plus-flow rather than a clean beam, which TWDEC handles less well.
- A broad mixture of species, since MHD acts on the conducting fluid as a whole.
In the train, MHD sits between the traveling-wave stage and the thermionic backstop, converting the ordered expansion of the plasma exhaust. Its own limits — electrode erosion, Hall effects, and conductivity — are covered in the pages that follow.