The MHD Faraday Generator

In the Faraday configuration, electrodes are placed transverse to the flow to collect the v×B current directly across the channel.

The straightforward geometry

The Faraday generator is the direct realization of the MHD principle. Plasma flows down a channel, a magnetic field crosses the flow, and the induced electric field drives current across the channel to electrodes on the two side walls. The output voltage is set by the field strength, the flow velocity, and the channel width; the current by the plasma's conductivity and the electrode area.

Segmented electrodes

A single pair of continuous electrodes suffers from short-circuiting axial currents driven by the Hall effect. Practical Faraday generators use segmented electrodes: many electrically isolated electrode pairs along the channel, each with its own load, so that the useful transverse current is collected while the parasitic axial current is suppressed. Segmentation is what lets the Faraday design work in the presence of strong Hall effects at high field.

Design drivers

• Higher field and higher flow velocity raise the induced voltage.
• Higher plasma conductivity raises the extractable current.
• Wider channels raise voltage but can lower current density — a geometry trade.
• Electrode segmentation controls Hall short-circuiting.

Where it fits

The Faraday configuration is the baseline MHD stage for converting the burner's ordered plasma exhaust. Its counterpart, the Hall generator, reconfigures the same channel to collect the axial current instead — useful at very high magnetic-field-to-conductivity ratios. The choice between them, and hybrid diagonal designs, is set by the burner's field and conductivity, discussed next.