Why do electrons create a Hall field inside an MHD generator channel?

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magnetohydrodynamic power generator Comparison of the operating principles of (A) a turbogenerator and (B) an MHD generator.

In a magnetohydrodynamic (MHD) generator, the Hall field arises due to the Hall effect, which occurs because electrons in the plasma possess significantly higher mobility than ions.1

When an electric load current flows across the channel, the electrons experience a force directed along the axis of the channel due to the interaction of the magnetic and electric fields. This force causes the electric current to flow at an angle across the channel rather than directly between the electrodes. Consequently, this displacement of charge establishes an additional electric field along the channel axis, known as the Hall field.1

To manage this phenomenon, engineers must either design segmented electrode walls to support the axial field or utilize the Hall field itself to drive current through an external circuit.1