Applications of Plasma Technologies to Material Processing

Giorgio Speranza, Wei Liu, Luca Minati

• Publisher: CRC Press
• Year: 2019
• eBook ISBN: 9780429559679
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Condensed Matter

This book provides a survey of the latest research and developments in plasma technology. In an easy and comprehensive manner, it explores what plasma is and the technologies utilized to produce plasma. It then investigates the main applications and their benefits. Different from other books on the topic that focus on specific aspects of plasma technology, the intention is to provide an introduction to all aspects related to plasma technologies. This book will be an ideal resource for graduate students studying plasma technologies, in addition to researchers in physics, engineering, and materials science.

Features

• Accessible and easy to understand
• Provides simple yet exhaustive explanations of the foundations
• Explores the latest technologies and is filled with practical applications and case studies

Chapter 1

Introduction

Since the 1980s, gases made of ionized particles have been used to synthesize materials with a specific desired surface chemistry or modify the chemical surface properties of an object. Such an ionized gas is called plasma and is usually referred to as the fourth state of matter in addition to the conventional solid, liquid, and gaseous forms. There is a rather broad variety of plasmas and they can be classified on the basis of different criteria, as summarized in Table 1.1.

TABLE 1.1 Classification of Plasmas Following Different Criteria

Criteria	Plasma
Operating pressure	low-pressure plasma
	atmospheric-pressure plasma
Thermodynamic equilibrium	thermal or equilibrium plasma (Telectron ≈ Tion ≈ Tgas)
	non-thermal plasma or non-equilibrium plasma (Telectron >> Tion ≈ Tgas)
	low-temperature plasma (Tgas < 2000 K)
	high-temperature plasma (Tgas > 2000 K)
Plasma generation	microwave frequency discharge (300 MHz–300 GHz)
	radio frequency discharge (450 kHz–3.0 MHz; 13.56 MHz)
	DC discharge
	dielectric barrier discharge
	corona discharge
	electric arc
	hollow cathode discharge
	electron beam
	plasma torch
	alternating current
Type of coupling	inductive coupling
	capacitive coupling

Low pressure and atmospheric plasmas can be distinguished on the basis of the operative pressure. In the first case, plasmas are generated in vacuum chambers where the precursor pressure typically ranges between a fraction of a millibar and 10⁻⁴ millibar. Atmospheric pressure plasma jets operate at ambient pressure without the need for complex equipment to reach low pressures. Due to the combination of simplicity, low cost, and wide possibilities of material treatment and modification, at present they are one of the most promising technologies. Plasmas can be classified also on the basis of temperature, that is, thermal equilibrium. In non-thermal plasmas, the temperatures of the electrons and the ions are in a thermal non-equilibrium. Due to the different mass, the temperature of the electrons (i.e., the kinetic energy) ranges between several electron volt (eV), whereas the temperature of the positively charged ions and neutral species is around room temperature. ^{1 , 2} This corresponds to a quite low overall plasma temperature ranging from 300 K to 1000 K. For this reason, the plasma is also called “cold plasma” and is favorable for the synthesis of materials at low temperature. In high-temperature plasmas, the temperatures are about 10⁷ K, which is typical of fusion plasmas ³ used to produce energy. We will focus on low-temperature, plasmas, which are used to modify the properties of materials.

The common feature of all the plasmas is that they use vaporized chemical compounds or gaseous precursors. In a typical plasma process, the precursor molecules are introduced and ionized in a chamber (the plasma reactor) with selected concentrations. Then, another kind of classification may be done on the basis of the energy source used to generate and sustain the plasma. The source of energy can be thermal energy, a flame, a laser, a microwave or radio frequency (RF), ...

Table of contents

• Cover
• Half-Title
• Title
• Copyright
• Contents
• Chapter 1 ■ Introduction
• Chapter 2 ■ Plasma Reactors
• Chapter 3 ■ Plasma Applications
• Chapter 4 ■ Concluding Remarks
• References
• Index