Nonlinear development of the two ion beam instability

The nonlinear development of the two ion beam instability has been experimentally investigated. The ion acoustic turbulence grows and stabilizes in conjunction with a significant change in the average ion distribution function. A quasilinear type theory is developed for ion waves in a boundary value problem which appears to predict most of the observed nonlinear behavior of the instability including excited waves and the growth of the background noise. A brief discussion of trapping and strong turbulence effects is given.