Nonlinear Theory of Density Fluctuations in Turbulent Plasmas

The level of rms density fluctuations in a turbulent plasma, saturated by modified particle orbits, are theoretically found to obey a remarkably general, but simple, formula. The results are obtained independently of the form of the dispersion relation and are therefore applicable to turbulence arising from a broad class of instabilities. The restrictions on the ratios between gyro, collision, and mode frequencies are explicitly given. Both the collisional and collisionless cases are discussed, and shown to be consistent with a variety of experiments.