On the generation of low-frequency waves in the solar wind in the front of the bow shock

The generation of low-frequency waves in the solar wind by the flux of protons accelerated in the magnetosheath is considered. It is shown that pulsations are produced in two partly overlapping frequency ranges. The growth rate of waves is maximal when the angle theta between the direction of the interplanetary magnetic field and the front of the bow shock is not equal to π/2. The dependence of the increment of perturbation on the solar wind velocity is analysed. A satisfactory agreement between theory and experimental results on the connection of Pc3-4 properties and parameters of the solar wind is obtained. (author)