Why are electrodes placed along the channel walls of an MHD generator?

In a magnetohydrodynamic (MHD) generator, electrodes are placed along the channel walls to enable the extraction of electric current from the system.1

The process relies on Faraday’s law of induction, which dictates that when a conductive gas (plasma) is accelerated through a magnetic field, an electromotive force is established in a direction perpendicular to both the gas flow and the magnetic field. By positioning electrodes on the channel walls parallel to the magnetic field, the generator can capture this induced potential and provide power to an external electric circuit.12

Depending on the specific configuration of the generator—such as a Faraday generator, Hall generator, or diagonal generator—these electrodes may be segmented or staggered to manage the Hall effect, a phenomenon where electrons experience a force along the channel axis, causing the current to flow at an angle.1