CAN A CHARGE-EXCHANGE INDUCED DENSITY RISE AT THE HELIOPAUSE EXPLAIN THE FREQUENCY DRIFT OF THE 3-KHZ VOYAGER SIGNAL

A physical model for the recently advanced interpretation of tile 3 kH z data [Gumett, Kurth et al., 1993] is proposed. Basing on the results of the flow dynamical model of the heliosheath [Czechowski and Grzedz ielski, 1993, 1994] we conclude that the post-shock salar wind (SW) pl asma, cooled down by charge-exchange with neutral hydrogen of LISM ori gin, should form a high density layer on the inner side of the surface of the heliopause. The model allows us to estimate the plasma density profile and the size of tile layer. These we use as input for MHD cal culation of (1) a transient shock moving through this layer towards th e heliopause and (2) of resulting 2 omega(p) (frequency) drift of VLF emissions generated at the shock. For the heliopause distance L=150-18 0 A.U. our model reproduces both tile time duration of the emissions a nd their typical frequency drifts.