Microwave Plasma Sources and Methods in Processing Technology

Ladislav Bardos, Hana Barankova

• Publisher: Wiley-IEEE Press
• Year: 2022
• Print ISBN: 9781119826873
• eBook ISBN: 9781119826897
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

A practical introduction to microwave plasma for processing applications at a variety of pressures

In Microwave Plasma Sources and Methods in Processing Technology, the authors deliver a comprehensive introduction to microwaves and microwave-generated plasmas. Ideal for anyone interested in non-thermal gas discharge plasmas and their applications, the book includes detailed descriptions, explanations, and practical guidance for the study and use of microwave power, microwave components, plasma, and plasma generation.

This reference includes over 130 full-color diagrams to illustrate the concepts discussed within. The distinguished authors discuss the plasmas generated at different levels of power, as well as their applications at reduced, atmospheric and higher pressures. They also describe plasmas inside liquids and plasma interactions with combustion flames.

Microwave Plasma Sources and Methods in Processing Technology concludes with an incisive exploration of new trends in the study and application of microwave discharges, offering promising new areas of study.

The book also includes:

• A thorough introduction to the basic principles of microwave techniques and power systems, including a history of the technology, microwave generators, waveguides, and wave propagation

• A comprehensive exploration of the fundamentals of the physics of gas discharge plasmas, including plasma generation, Townsend coefficients, and the Paschen curve

• Practical discussions of the interaction between plasmas and solid surfaces and gases, including PVD, PE CVD, oxidation, sputtering, evaporation, dry etching, surface activation, and cleaning

• In-depth examinations of microwave plasma systems for plasma processing at varied parameters

Perfect for researchers and engineers in the microwave community, as well as those who work with plasma applications, Microwave Plasma Sources and Methods in Processing Technology will also earn a place in the libraries of graduate and PhD students studying engineering physics, microwave engineering, and plasmas.

1
Basic Principles and Components in the Microwave Techniques and Power Systems

1.1 History in Brief – From Alternating Current to Electromagnetic Waves and to Microwaves

The greatest discoveries and developments connected with the great names in the field of alternating current (AC) and related systems were already dated in the early nineteenth century, see [Ref. 1.1]. However, an important basic invention was the battery, a source of electricity, disclosed by the Italian scientist Alessandro Volta in 1799. This simple source of a direct current (DC) allowed many important experiments with electricity. In 1820, Danish physicist Hans Christian Ørsted discovered an effect of electricity on the magnetic field and his findings were confirmed by the experiments of French physicists Andre-Marie Ampere and François Arago. The parallel wires with DC current visibly attracted or repelled each other according to the mutual current directions. However, in 1830, English scientist Michael Faraday discovered the ability to generate electricity by moving magnets and the corresponding principle of the electric induction. These new effects based on the electric induction inspired the Serbian-American electrical and mechanical engineer Nikola Tesla and led to his inventions of an alternating current generator which used a rotating magnetic field, the Tesla coil, the transformation of AC voltages to high voltages or vice-versa, as well as other inventions patented at the end of 1887. Besides his fundamental inventions, Tesla is considered a pioneer in radar technology, X-ray technology, and remote control.

In 1860, Scottish scientist James Clerk Maxwell proposed the electromagnetic disturbances longer than infrared (IR) radiation. He explained theoretically how electric and magnetic fields can form electromagnetic waves and developed a theory known as Maxwell’s equations, see [Ref. 1.2]. In 1888, the German physicist Heinrich Hertz used an electric spark arrangement and a simple capacitor made from a Leyden jar for the generation of electromagnetic waves, see Ref. [1.3]. He was the first person who was able to transmit and receive radio waves. That is why the frequency unit, 1 Hz = 1/s, is called Hertz. In 1897, an application of Hertzian waves was patented for long-distance radio telegraph communication by Italian electrical engineer Guglielmo Marconi. Radio waves are only part of electromagnetic waves used in radio communications. The whole spectrum of electromagnetic waves is graphically illustrated in Figure 1.1. The spectrum can be roughly divided into the following wavelengths (λ):

Figure 1.1 Graphical illustration of the frequencies and wavelengths in the spectrum of the electromagnetic waves. An optical spectrum is inserted between ultraviolet and infrared waves. The part of the visible light is shown in spectral colors.

Gamma (γ) rays	λ ≈ 1–100 pm (picometer)
X-rays	λ ≈ 100 pm–100 nm
Ultraviolet (UV) light	λ ≈ 100–300 nm
Visible light	λ ≈ 350–750 nm
IR	λ ≈ 750 nm–1 mm
Microwaves (μ)	λ ≈ 1 mm–1 m
Radio waves	λ ≈ 1 m–100 km

The electromagnetic waves are moving with the speed of light (c = 3 x 10⁸ m/s) and the corresponding frequencies can be calculated from the expression f = c/λ. This gives the following approximate frequency values:

Gamma (γ) rays	f ≈ 3 × (10^20–10^18) Hz
X-rays	f ≈ 3 × (10^18–10^15) Hz
UV light	f ≈ 3 × 10^15–10^15 Hz
Visible light	f ≈ 9 × 10^14–4 × 10^14 Hz
IR	f ≈ 4 × 10^14–3 × 10^11 Hz
Microwaves (μ)	f ≈ 3 × 10^1–3 × 10^8 Hz
Radio waves	f ≈ 3 × 10^8–3 × 10^4 Hz

In case you need to recall what units are used in the high and very high frequencies, see the following list:

kHz	10^3 Hz (Kilohertz)
MHz	10^6 Hz (Megahertz)
GHz	10^9 Hz (Gigahertz)
THz	10^12 Hz (Terahertz)
PHz	10^15 Hz (Petahertz)
EHz	10^18 Hz (Exahertz)
ZHz	10^21 Hz (Zettahertz)
YHz	10^24 Hz (Yottahertz).

The ideas presented by Tesla along with many ongoing experiments with electromagnetic waves in many countries led to the development of electromagnetic detection of objects, i.e. radar, see the condensed history in Ref. [...

Table of contents

• Cover
• Title page
• Copyright
• Table of Contents
• Foreword from the Authors
• 1 Basic Principles and Components in the Microwave Techniques and Power Systems
• 2 Gas Discharge Plasmas
• 3 Interactions of Plasmas with Solids and Gases
• 4 Microwave Plasma Systems for Plasma Processing at Reduced Pressures
• 5 Microwave Plasma Systems at Atmospheric and Higher Pressures
• 6 New Applications and Trends in the Microwave Plasmas
• 7 Appendices
• Index
• End User License Agreement