MHD Efficiency & Loss Channels
MHD conversion efficiency is bounded by internal resistive losses, electrode drops, and end effects, all traded against field and channel design.
The efficiency picture
An MHD generator extracts a fraction of the flow's kinetic-plus-thermal energy as electrical output. The efficiency is set by how much of the induced power reaches the external load versus how much is dissipated inside the channel. The dominant internal loss is ohmic dissipation in the plasma itself: the same finite conductivity that lets current flow also resists it, heating the plasma instead of the load.
The loss channels
- Ohmic dissipation: internal resistance of the finite-conductivity plasma.
- Electrode voltage drop: the sheath at each electrode consumes some voltage.
- Hall short-circuiting: parasitic axial currents in a poorly segmented Faraday channel.
- End losses: current leakage and non-uniform fields at the channel inlet and outlet.
- Heat leaving with the flow: energy not extracted, handed downstream to thermionic or thermal recovery.
How the design pushes back
Higher magnetic field raises the induced power relative to the ohmic loss, improving efficiency — the direct benefit of the burner's ultra-high field. Electrode segmentation or a Hall configuration controls the axial short-circuit. Operating the channel in the hot, high-conductivity inlet region keeps ohmic losses down. Careful inlet and outlet shaping limits end effects.
Honest framing
MHD conversion is a mature concept with a long experimental record in fossil-fired systems, but a fusion-exhaust MHD channel at these fields is a design-and-simulation exercise here, not a measured result. Its role is to raise the train efficiency by converting the ordered flow that the traveling-wave stage leaves behind; the burner test unit around 2032 is where the integrated performance is meant to be shown.