Applications of Electron Emission Physics

1. Auflage 2027
ISBN: 978-1-394-19956-3
Verlag: John Wiley & Sons Inc

Buch, Englisch, 368 Seiten

From theory to device construction in electron emission technology

Constructing, modeling, and operating electron emission devices demands a command of both underlying physics and practical engineering realities. Applications of Electron ??Emission Physics is written by Kevin L. Jensen, an APS Fellow, a recipient of the Sigma Xi Applied Science Award for his work on electron emission, a research physicist at the Naval Research Laboratory, and now at the University of Maryland. He delivers field-tested concepts for the modeling and simulation of electron sources, particularly those based on thermionic, field, and photoemission, grounded in decades of hands-on research and instruction experience.

Applications of Electron Emission Physics covers the use of electron emission theory and models to the understanding and operation of electron emission devices alongside a detailed treatment of electron beam physics. The text provides algorithms needed to simulate theoretical models and interpret experimental results obtained with both lab-scale and large-scale electron sources. Included code algorithms enable readers to perform their own numerical computations, analyze data, simulate, and validate experimental observations against theoretical predictions.

Readers will also find: - Field-tested methods for simulating quantum mechanical tunneling and emission, and modeling electron sources modified by changes to materials, emitter shape, and the application of coatings
- A detailed overview of electron beam physics connecting source design to downstream beam transport and performance
- Algorithmic tools for interpreting experimental results from both laboratory-scale and large-scale electron source configurations
- Code algorithms enabling independent numerical computation, data analysis, simulation, and direct comparison of theory with experiment
- Practice-oriented guidance shaped by the author’s extensive research at both the Naval Research Laboratory since 1990 and the University of Maryland since 2023

Designed for advanced graduate students, PhD candidates, academics, and researchers in solid state physics, materials science, electron transport, and beam physics, this book serves both users and developers of electron sources who require a unified treatment connecting emission theory directly to device construction, operation, and experimental analysis.

Autoren/Hrsg.

Jensen, Kevin L.

Inhaltsverzeichnis

1 Dispenser Cathodes

1.1 Miram Curves

1.1.1 Longo Equation

1.1.2 Effect of GTF Emission

1.1.3 Effect of Multiple Crystal Faces

1.2 Diffusion of Coatings

1.2.1 Point Source Model

1.2.2 Lattice Gas

1.2.3 A Simple Model of the Diffusion Coefficient

1.2.4 Modeling Diffusion Using a Shuffle Algorithm

1.2.5 Adatom Motion and Diffusion Coefficients

1.2.6 The Darken Equation

1.2.7 Adatom Interactions

1.3 Evaporation of Coatings

1.4 Knudsen Flow Through Pores

1.5 Lifetime of a Sintered Wire Controlled Porosity Dispenser Cathode

2 Field Emitters

2.1 Field Enhancement

2.2 Hemispheres and Notional Emission Area

2.3 Point Charge Model

2.4 Schottky’s Conjecture

2.5 Assessment of the Tip Current Models

2.6 Line Charge Models

2.6.1 Simple Line Charge Model

2.6.2 Tapered Line Charge Model

2.7 Prolate Spheroidal Representation

2.7.1 Hyperbolic Emitter

2.7.2 Ellipsoidal Emitter

2.8 A Hybrid Analytic-Numerical Model

2.8.1 Analytic: the Saturn Model

2.8.2 Numerical: Boundary Element Methods

2.8.3 Semi-Analytic Model

2.9 Shielding

2.10 Statistical Variation

2.11 Paschen’s Curve

2.11.1 Modified Paschen’s Curve

2.11.2 Ions and the Emission Barrier

2.12 Breakdown

2.12.1 Nottingham Heating

2.12.2 Henderson Cooling

2.13 Fibers and Nanowires

2.13.1 Joule Heating

2.13.2 Analytic Model of Temperature

2.13.3 Numerical Model of Temperature

3 Photoemitters

3.1 Scattering Consequences

3.2 Basic Theory

3.3 Three Step Model

3.4 Moments Model

3.4.1 Metals

3.4.2 Semiconductors

3.5 Reflectivity and Penetration Factors

3.6 Lorentz-Drude Model of the Dielectric Constant

3.6.1 Harmonic Model

3.6.2 Quasi-Classical Boltzmann Model

3.6.3 Quantum Model

3.7 Scattering Contributions

3.7.1 Dowell-Schmerge Relation

3.7.2 Scattered Electron Contribution

3.7.3 Shell and Sphere Models

3.8 Low Work Function Coatings

3.8.1 Simple Dipole Model

3.8.2 Topping Model

3.8.3 Gyftopoulos-Levine Model

4 Secondary Emission

4.1 Diamond Amplifier Concept

4.1.1 Bethe Approximation

4.1.2 Penetration Range and Initial Conditions

4.2 Monte Carlo Methods

4.2.1 Poisson Statistics

4.2.2 Random Number Generation

4.2.3 Scattering and Self-Scattering

4.3 Relaxation Time

4.3.1 Ionized Center

4.3.2 Sinusoidal Potential

4.3.3 Electron-Electron Scattering

4.3.4 Acoustic Phonon Scattering

4.3.5 Optical Phonon and Ionized Impurity Scattering.

4.3.6 Scattering Angles

4.3.7 Allowed Final States

4.4 Monte Carlo and Diamond Amplifier Response Time

5 Space Charge

5.1 Generalized Child’s Law

5.1.1 Constant Density Approximation

5.1.2 Constant Current Approximation

5.2 Transit Time Model

5.3 Space Charge for a Single Emitter

5.3.1 Poisson Distribution

5.3.2 Transit Time Model

5.3.3 Sequential Emission Model

5.4 Space Charge for an Array

6 Electron Beam Physics

6.1 Electron Orbits and Cathode Area

6.2 Beam Envelope Equation

6.3 Emittance for Flat and Uniform Surfaces

6.3.1 Liouville’s Theorem and Normalized rms Emittance

6.3.2 Thermal Emittance

6.3.3 Field Emission Emittance

6.3.4 Comparisons of the 1D Emittance Equations

6.3.5 Space Charge and Emittance

6.3.6 Secondary Emission and Emittance

6.4 Emittance for A Bump

6.4.1 Trajectory Evaluation

6.4.2 Hemispheres and Emittance

6.4.3 Impulse Approximation

6.4.4 Single Hemisphere Emittance Parameters

6.4.5 A Notional Emittance for a Hemisphere

6.4.6 An Array of Emitters

6.5 Emittance and Realistic Surfaces

6.5.1 Emittance and Undulating Surfaces

6.5.2 Intrinsic Emittance and Space Charge

6.6 Particle-in-Cell Models

7 Algorithms

7.1 Permutation Algorithm

7.2 Least Squares Fitting of Data

7.3 Wave Function and Density Algorithm

7.4 Root Finding Methods

7.4.1 Method of Bisection

7.4.2 Method of Iteration

7.4.3 Final Correction

7.5 Simple ODE Solvers

7.5.1 First order

7.5.2 Second order

7.6 Roots of the Quadratic Image Charge Barrier

7.7 Zeros of the Airy Function

7.8 Sodium Exchange-Correlation Potential

7.9 Field Dependent Work Function

7.10 Evaluation of the Point Charge Model Functions

7.11 Modeling of Field Emitter I(V ) Data

7.12 Modeling a Log-Normal Distribution of Field Emitters

7.13 Simple Shell and Sphere Algorithm

7.14 Gyftopoulos-Levine Work function Algorithm

7.15 Poisson Distributions

7.15.1 Generation

7.15.2 Test of Acceptance-Rejection Method

7.16 Electron-Electron Relaxation Time

7.17 Resistivity and the Debye Temperature

7.18 Orbits in a Magnetic Field

7.19 Trajectory of a Harmonic Oscillator

7.20 Trajectories for Emission from a Hemisphere
7.21 Monte Carlo and Integration

Über Autor(innen)

KEVIN L. JENSEN, PhD, was a Research Physicist in the Materials and Systems Branch, Materials Science and Technology Division, at the Naval Research Laboratory (retired 2023), and is now at the Institute for Research in Electronics and Applied Physics at the University of Maryland. A Fellow of the American Physical Society and a recipient of the Sigma Xi Applied Science Award for his work on electron emission, he has authored or co-authored over 200 articles, chapters, encyclopedia entries, and books, and served as Principal Investigator for programs investigating field, photo, thermionic, and secondary emission sources for microwave devices, particle accelerators, and Free Electron Lasers.