On a possibility of further heating of a tokamak plasma by microwave injection

A possibility of further heating of a Tokamak plasma by means of microwave is estimated from the energy balance equations with rough assumptions. It is shown that the ion temperature is expected to rise with the electron temperature even when all the wave power is directly absorbed by the electrons, because energy relaxation time between electrons and ions becomes shorter as the plasma density increases. As an example of the numerical values in this framework of calculation, the ion temperature rises to about 4 keV from the initial value of 900 eV when 20 MW microwave is injected to a plasma of 60 m³ volume at the density of 8 x 10¹³ cm^-3 with the magnetic field of 5 T. (author)