Dielectric permeability at accounting of electrons contribution into their own screening

TL;DR

This paper presents a new expression for dielectric permeability considering electron contribution to screening, explaining ionic-sound oscillations in tokamak plasma with altered temperature relations.

Contribution

It introduces a modified dielectric permeability formula accounting for electron screening effects, challenging existing theories about ionic-sound oscillations in plasma.

Findings

Ionic-sound oscillations observed in tokamak plasma contradict previous theories.

The new dielectric expression alters conditions for ionic-sound excitation.

Phase velocity of ionic-sound fluctuations remains unchanged under new conditions.

Abstract

In this paper the experimental fact of presence of ionic - sound oscillations in plasma of tokamak DIII-D is given for plasma with additional heating by means of a neutral hydrogen beam. It contradicts modern theoretical representations about an opportunity of the build-up of such type of oscillations in plasma, when an ionic temperature is biger than an electronic one. Inasmuch as electrons provide the own screening by means of pushing aside forcibly around of itself of electrons and by baring an ionic skeleton their polarizing cloud should be of bigger radius than radius of Debye. Therefore the authors have suggested search of the decision of a kinetic equation, by taking into account the electrons contribution into their own screening, by means of inserting of some multiplier for Debye radius and of appropriate dividing of frequency onto this factor. In result a new expression of dielectric permeability is received which pass into former when the entered multiplier is identically equal to unit. The analysis of this expression has shown, that frequencies characteristics of possible low-frequency and high-frequency fluctuations have remained with former plasma frequencies, ionic - sound fluctuations have received the same phase velocity, but the condition of their excitation became different which for pure deuterium plasmas now has got a view: relation of the ionic temperature to the electronic is smaller than ten, instead of a former condition - relation of the electronic temperature to ionic one is biger than ten.