Distribution of MHD wave activity in the foreshock region and properties of backstreaming protons

Magnetic field and plasma data obtained by ISEE 2 experiments in the earth's foreshock region have been used, in conjugation with a shock model, to correlate with geometrical parameters the intensity of MHD trubulence and some moments of the distributions of back-streaming protons. The geometrical parameters are the distance of the observation point from the proton foreshock boundary and the distance from the shock surface. The results obtained allow a preliminary discussion of two basic problem of the physics of the foreshock. These are (1) the relative role of shock struture and/or wave particle interaction in determining the form of the backscattering ion distribution and (2) the physical mechanism determining the observed saturation of the MHD turbulence