Here the MHD generator is similar to that of rocket engine except surrounded by a magnet that is to produce external magnetic field. Once the gas is heated to 2750 to 3000 K and pressurized to 7 to 15 atm pressure. A small fraction Ionized alkali metal like cesium or potassium is injected to increase the electric conductivities of gas. While expanding in the presence of powerful magnet, the positive and negative ions moves tot he electrodes and constitute an electric current. Which is basically Faraday's law of motional electromagnetic induction. But not the usual one, in which charge flows in a conductor when time varying magnetic filed is applied. Here both electrons and heavy gas particles are in thermal equilibrium due to high collision frequencies and energy transfer/collision.
While in closed MHD system plasmas are thermally non-equilibrium with elevated electron temperatures in inert gas plasmas to keep sufficient conductivity but relatively low temperature with open cycle system. To achieve this we use the concept of ohmic heating under relatively low collision frequencies between electrons and ions.
| Diagram of open cycle MHD generator |
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