Magnetohydrodynamic generators are normally used as eihter an attachment to recycle wasted heat and flow of other generators, or used to absorb the energy from rocket thrusters.
However, I'm trying to understand why not use the MHD's as the primary source for power generation while using configurations such as a Tokamak or a Stellarator to confine its combustion and plasma?
Either using the combustion of fossil fuels or the combustion of liquid oxygen/hydrogen rockets, it could be interesting to use it as a compact generator that directly converts electricity from the reaction.
Regardless of what I believe it could be interesting, the specialists on the subject do not use MHD generators in such a way. And I assume there is a good reason for that (such as its low efficiency), which I'm trying to understand.
In case of burning fossil fuels in an MHD generator leads to plasmas with comparatively low ionisation, which makes such a generator less efficient (you need a good electrical current for such a generator to work properly). Furthermore, an ordinary turbine is much more cost effective for heated gases.
In the case of stellarators/tokamaks you want to have a good confinement of the plasma over a long time (as long as possible). However, if you use your hot plasma specifically as a kind of gaseous conductor to drive a large current through a magnetic field but this breaks the confinement and your fusion rates will go down drastically (or stop entirely).
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