Plasma is a charged system and therefore can be confined through the use of appropriate electromagnetic fields, generated by passing current in special coils: the geometry of the fields necessary for confinement can be quite complex. Knowing the strength and the peculiar shape of the magnetic field it is possible to deduce the overall temperature of the plasma (the so-called calculation of the plasma frontier).
In general, temperatures of the order of millions of degrees are reached in Tokamak reactors.
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