---
author:
- 'Eduard P. Kontar'
title: Dynamics of electron beams in the solar corona plasma with density fluctuations
---

Introduction
============

One of the challenging problems in the theory of type III bursts, widely discussed in the literature, is the fine structure of the bursts. The fine structure is observed in almost all ranges of frequencies from GHz ([@Benz82]; [@Benz96]) to a few tens of kHz in interplanetary space ([@Chaizy95]). Direct observations of Langmuir waves and energetic electrons show that Langmuir waves have rather clumpy spatial distribution whereas the electron stream seems rather continuous ([@Lin81]; [@Chaizy95]).

There are a few alternative ways to explain the observational data. The existing theories can be roughly divided into three groups in accordance with the electron beam density or the energy of the Langmuir waves. The first group of theories is based on the assumption that nonlinear instabilities of strong turbulence theory can suppress quasilinear relaxation ([@Papadopoulos74]) and lead to extreme clumpiness of the spatial distribution of Langmuir waves ([@Thejappa98]). However, some observations and theoretical studies ([@Cairns95]) raise doubts as to whether the Langmuir turbulence level is high enough for strong-turbulence processes. The second, recently developed group of theories, is based on the 