Introduction to Plasma State

**Chapter 1**

**Abstract**

Introduction: Plasma Parameters

Plasma is ionized gas (partially or fully). Overwhelming majority of matter in the universe is in plasma state (stars, Sun, etc.). Basic parameters of plasma state are given briefly as well as classification of plasma types: classic-quantum, idealnonideal, etc. Differences between plasma and neutral gas are presented. Plasma properties are determined by long distance electrostatic forces. If spatial dimensions of a system of charged particles exceed the so-called Debye radius, the system may be considered as plasma, that is, a medium with qualitatively new properties. The expressions for Debye radius for classical and quantum plasma are carried out. Basic principles of plasma description are presented. It is shown that plasma is a subject to specific electrostatic (or Langmuir) oscillations and instabilities. Simplest plasma models are given briefly: the model of "test" particle and model of two (electron and ion) fluids. As an example, Buneman instability is presented along with qualitative analysis of its complicate dispersion relation. Such analysis is typical in

**Keywords:** plasma, quasi-neutrality, Langmuir frequency, Debye length, simplest

Everyone knows the three states of matter: solids, liquids, and gases. Plasma is often called the fourth state of matter; bear in mind that with increasing temperature, the following transitions take place: solids-liquids-gases-plasma. Under the last transition, atoms lose electrons. Plasma consists (along with neutral atoms) of charged particles: electrons and positively charged ions (single and/or multiple ionized). This definition of plasma is far from complete. The complete definition of plasma is, in fact, impossible. It must cover a very wide range of phenomena in a

Plasma is very common in the universe. Most of the substance in it (more than 99%) is in plasma state. Media consisting of ionized atoms is found almost everywhere. The upper layers of the Earth's and stellar atmospheres, interstellar medium, etc. actually are in plasma state. Stellar plasma is another widespread example. In the plasma of stars, in particular the Sun, reactions of the synthesis of light elements, the so-called thermonuclear reactions, provide a huge release of energy and plasma heating. Currently, scientists from many countries around the world are studying the possibility of creating such a high-temperature plasma in terrestrial conditions, setting the task of implementing controlled thermonuclear fusion and

and Simplest Models

plasma theory. It allows to easily obtain the growth rate.

providing humanity with an inexhaustible supply of energy.

plasma models, unstable plasma oscillations

**1. Introduction**

wide variety of conditions.

**3**

*Eduard Vardges Rostomyan*
