''Drift'' excitation of Alfven waves by trapped electrons in Tokamak at βsub(J) approximately > 1

A study is made of the ''drifting'' buildup of the alfven waves by trapped electrons in the tokamak, where the plasma pressure is comparable with the pressure of the poloidal magnetic field Bsub(J) approximately > 1%. The interaction of trapped electrons with alfven waves is due to compressibility of the electron gas in a curved magnetic field and collisions of trapped electrons with ions and with flight electrons (dissipative interaction in a curved magnetic field). At Bsub(J) approximately > 1% the tokamak plasma is unstable. The instability increment is proportional to the square root of the electron collision frequency. Transverse wavelength of growing perturbations is of the order of the larmour ion radius, the longitudinal one of the tokaak size over a large azimuth, and the frequency is of the order of the electron ''drifting'' frequency