Theory of type II radio emission from the foreshock of an interplanetary shock

We present an analytical model for type II solar radio bursts and then appl y it to an observed type II event. Electron beams are produced in the fores hock of an interplanetary shock via shock drift acceleration. Reflection is treated in the de Hoffman-Teller frame with efficiencies modeled by a loss cone that incorporates the effects of the static cross-shock potential phi. Stochastic growth theory is used to treat electron beam driven Langmuir wa ve growth in the type II foreshock. Nonlinear wave-wave interactions are us ed as the mechanisms for converting Langmuir wave energy into freely propag ating radio emission. The electron beams produced in the foreshock have a w ide range of speeds and number densities. These electron beams are qualitat ively consistent with observations in a type II foreshock as well as earlie r theoretical predictions, and observations in Earth's foreshock. Significa nt levels of Langmuir waves and f(p) and 2f(p) emission are predicted. In p articular, the predicted volume emissivities are similar to those predicted for type III bursts. The simple model developed for the source environment of the type II event on August 26, 1998, produces fluxes in reasonable agr eement with observation.