MACROSCOPIC ELECTRIC-FIELDS DRIVEN BY LOWER-HYBRID TURBULENCE AND ACCELERATION OF THERMAL ELECTRONS IN THE FOOT OF QUASI-PERPENDICULAR SHOCKS

A new mechanism is suggested that draws non-resonant thermal electrons into a higher-velocity range, where they can be effectively accelerat ed by waves. We argue that the acceleration of a small number of pre-e xisting resonant particles influences the dynamics of the bulk plasma and results in a macroscopic electric field. The solution for the spat ial dependence of this electric field is obtained, and it appears to b e a new type of electrostatic shock, which forms only in the presence of background turbulence. This field enriches the region of resonant p articles with thermal electrons, which leads to a build-up of an exces s of accelerated particles. The number of accelerated particles is cal culated. This mechanism appears as a good candidate to explain electro n acceleration in the foot of quasi-perpendicular shocks.