Waves need to be able to penetrate into the center of plasma for heating tokamaks. In recent years, generation of steady – state currents in plasma has been considered using Radio - Frequency waves. In particular it has been predicted that these currents are produced by waves that their phase velocity is several times greater than electron thermal velocity. This prediction has been confirmed by numerous experiments in which the current has been driven by lower hybrid waves. Current drive has generated toroidal electric current in the plasma in a tokamak. Component of toroidal magnetic field is greater than component of poloidal magnetic field but our purpose is to increase poloidal magnetic field so that cause to increase toroidal current in plasma. If the wave phase velocity is approximately equal to the electron runaway velocity, RF energy could be converted to poloidal field energy. The interaction of radio frequency waves with a plasma is described by the Fokker - Planck equation with an added quasilinear term. The Fokker - Planck equation then reduces to an equation in time and two velocity (or momentum) dimensions only. Here we investigated lower hybrid wave interactions in the T and Alcator C – Mod reactors. Then we found found optimal lower hybrid wave powers and frequencies for these reactors. Also comparison of the T tokamak and Alcator C – Mod torus tokamak shows that both have been able to create a high driving current. Our results indicated that the use of lower hybrid waves in improved spherical tokamak T compared to the Alcator C – Mod torus is much better and more efficient.
