Providing of fusion situation is the most important affair in fusion reactors. These conditions are just provided by increasing particle’s temperature and density. In this way the collision rate between deuterium and tritium would be raised. In large tokomaks such as JET and ITER, heating process is done by D-T fuel injection; confinement by very high magnetic fields (around 30 T) and creating inductive current derive. At 1999 in L a new generation of fusion reactors was unveiled which presented some extraordinary characteristics. NSTX was a spherical torus that provided so compact and high confined plasma, just by means of 0.5 T magnetic fields. For this respect it was a feat. With respect of its small radius it yields so stable plasma so that its plasma is estimated by an over dense plasma. Due to its high temperature using of direct probing in order to determine the plasma characteristic features such as density, temperature and …is a fatal problems; in this way the only solution is waves. On the other hands buy considering the conductive property of plasma, prorogation of wave is a challenge by its own. However, by wave theory development we can overcome this matter. Some wave modes can propagate through the plasma. X and O and Bernstein wave are the most important of them. According to wave theory in plasma environment an X or O waves can convert to a Bernstein wave in a special out layer so called UHR. The Bernstein wave can easily propagate toward the inner areas with higher density and be damped in electron cyclotron harmonics. Inasmuch as the UHR has so vital role in this conversion and also it is so sensitive to density and magnetic field fluctuations in this kind of reactors, so its simulation is essential. Key Words : deuterium, tritium, tokomak, JET, ITER, NSTX, O wave, X wave, Bernstein wave, UHR, electron cyclotron harmonic