Ion Source: with 26 tables/Huashun Zhang. –Beijing; Hong Kong; New York: Science Press; Berlin; Heidelberg; New York; Barcelona; Hong Kong; London; Milan; Paris; Singapore; Tokyo: Springer, 1999. ISBN 3-540-65747-9 (Springer) ISBN 7-03-007351-7 (Science Press)

　　Preface

　　Ion source is a rapidly evolving applied science and technology with wide applications. Its development relies on many scientific fields and industrial technologies.

　　Ion sources are important in many fundamental sciences, such as atomic physics, plasma physics, plasma chemistry, nuclear physics. Their pioneering developments and applications include the scientific and technological frontiers of mass spectroscopy, accelerators, isotope separation, ion propulsion, controlled thermonuclear fusion and radiation therapy etc. They are also important to many industrial processes of ion importation, ion etching, microanalysis, microfabrication and others.

　　The development of ion sources dependents not only on various scientific knowledge, including gas discharge, atomic physics, plasma physics, surface physics, intense ion optics and computational mathematics, but also on many newly developing technologies, which include plasma and beam diagnostics, sophisticated high voltage equipment, modern vacuum systems, intense and quality magnetic fields, high-intensity electron guns, microcomputers and special materials.

　　According to limited statistics, the number of principal types of sources exceeds one hundred. Their developments are driven by many areas of applications which propose new different requirements and anticipate further developments.

　　Ion source is an old science, but still a rapidly developing science. Although it has been studied for more than eighty years, it is still a “”semi-empirical” Science and technique. Numerous papers---approximately 400 papers per year during the past decade---have been presented in a wide variety of journals and conference proceedings. As a result of the emergence of new applications for ion sources, more scientists and engineers have the need to systematically study and use ion sources.

　　This book is intended to serve a threefold purpose, in a manner it is useful to those who are new to this field as well as the experts. First, to provide comprehensive information that is easily understood and provide fundamental and technical knowledge associated with ion sources in sufficient depth to be useful to the new or laboratory workers. Second, to briefly review the essential principles and major research achievements to date of various sources giving available recent information on the design and operation of the source. Third, to present a great quantity of commonly used source diagrams, drawings, curves, physical contents, useful formulas, references, etc., thus making the book a useful practical reference.

　　Fundamental knowledge regarding source performance, gas discharge, extraction system and space-charge neutralization is presented in Chapters 1, 2, 3 and 9. Positive ion sources are introduced in Chapter 4. The principles for producing negative and multi-charged ions are discussed in Chapters 6 and 8. The processes determining the mass and energy spectra of sources are discussed in Chapter 7. The giant ion sources, multi-charged sources and negative sources, which have developed fastest during the past thirty years, are discussed in detail in Chapters 5, 6 and 8. Finally, beam diagnostic is introduced in Chapter 10. Many useful physical constants and data are given in the appendix. This book has extracted its contents form more than 4000 articles published in different journals and other publications, to avoid too much consumption of space only about one thousand foremost references, which are sufficient to guide the readers to further information on topics of particular interest, are given.

　　The original manuscript of this book was written by Zhang Huashun based on his book, in Chinese, “Ion Source and Powerful Neutral Beam Injectors”. Parts of Chapters 2, 4 and 9 of the Chinese book were written by Wan Chunhou, likewise parts of Chapter 5 were written by Wang Gengjie. The author thanks Dr. P. Allison and K. Prelec for their encouragement for this English version. The English manuscript was extensively reviewed and reedited by Mr. C. W. Schmidt, who made a great contribution to the book quality.

　　Thanks are due to many publishers, organizations and persons for permission to reproduce materials and figures from various books and journals.

　　Contents

　　1 INTRODUCTION

　　1.1 Major Applications and Requirements

　　1.2 Performances and Research Subjects

　　1.3 Historical Development

　　2 GAS DISCHARGE FUNDAMENTALS

　　2.1 Thermionic Emission

　　2.2 Secondary Electron Emission

　　2.3 Surface Ionization

　　2.4 Elastic and Inelastic Collisions

　　2.5 Ionization Cross Section

　　2.6 Recombination of Charged Particles

　　2.7 Mobility

　　2.8 Diffusion Coefficient

　　2.9 Particle Distribution in a Retardation Region

　　2.10 Ambipolar Diffusion

　　2.11 Magnetic Field Influence on Particle Motion

　　2.12 Fundamentals of a Hot-Cathode Arc Source

　　References

　　3 EXTRACTION SYSTEMS FOR ION SOURCES

　　3.1 Extraction Systems Requirements

　　3.2 Extraction System with a Solid Emitter

　　3.3 Emittance and Brightness

　　3.4 Ion Extraction from a Plasma

　　3.5 Geometry of Extraction Systems

　　3.6 Research Methods of Extraction Systems

　　3.7 Some Other Problems

　　References

　　4 POSITIVE ION SOURCES

　　4.1 Classification of Ion Sources

　　4.2 Hot Cathodes

　　4.3 Arc Source in a Uniform Magnetic Field

　　4.4 Hot-Cathode Penning Source

　　4.5 Duoplasmatron Ion Source

　　4.6 Hot-Cathode “Freeman” Source

　　4.7 Broad Beam Ion Sources

　　4.8 Cold-Cathode PIG Source

　　4.9 Radio-Frequency Ion Source

　　4.10 Technology of Heavy Ion Sources

　　References

　　5 GIANT ION SOURCES

　　5.1 DuoPIGatron Ion Source

　　5.2 Periplasmatron Ion Source

　　5.3 Multifilament Ion Source

　　5.4 Magnetic Multipole Ion Source

　　5.5 Hall Accelerator

　　5.6 Cluster Ion Source

　　5.7 Intense Pulsed Ion Source

　　References

　　6 MULTIPLY CHARGED ION SOURCES

　　6.1 Introduction

　　6.2 Formation of Multiply Charged Ion

　　6.3 Major Research of MCIS

　　6.4 Multiply Charged Electron Beam Ion Source

　　6.5 Conventional Multiply Charged Ion Sources

　　6.6 Microwave Ion Sources

　　6.7 High Density Plasma Sources

　　References

　　7 MASS AND ENERGY SPECTRA OF ION SOURCES

　　7.1 Mass Spectra of a Hydrogen Ion Source

　　7.2 Energy Spectra of Ion Sources

　　References

　　8 NEGATIVE ION SOURCES

　　8.1 Introduction

　　8.2 Negative Ion Formation Processes

　　8.3 Volume Formation of Negative Ions

　　8.4 Surface Formation of Negative Ions

　　8.5 Destruction of Negative Ions

　　8.6 Volume H－ Ion Source

　　8.7 Surface-Plasma H－ Ion Source

　　8.8 Charge-Transfer Negative Ion Source

　　8.9 Cesium Sputter Negative Ion Source

　　8.10 Dissociative Source by Positive Ion Impact

　　8.11 Surface Negative Ionization Ion Sources

　　References

　　9 SELF-NEUTRALIZATION OF BEAM SPACE CHARGE

　　9.1 Self-Neutralization of Positive Beams

　　9.2 Dynamic Decompensation of the Beam Space Charge

　　References

　　10 BEAM DIAGNOSTICS FOR ION SOURCES

　　10.1 Introduction

　　10.2 Beam Current Measurements

　　10.3 Beam Density Profile Measurements

　　10.4 Beam Emittance Measurement

　　10.5 Ion Energy Spectra Measurements

　　10.6 Mass or Charge Spectra Measurements

　　References

　　APPENDIX

　　A1. Physical Contents

　　A2. Common Units and Conversion Factors

　　A3. Densities, melting Points, Boiling Points, Vapor Pressure,

　　Some Source Feed Compounds

　　A4. Work-function, First and Stepwise Ionization Potential,

　　Electron Affinity of the Elements

　　A5. The Calculated Values of the Stepwise Ionization

　　Potential of Noble Gases

　　A6. The Minimum Workfunctions of Amorphous Surfaces

　　with Adsorbate Materials at Optimum Layer

　　A7. Solution of the Plasma-Sheath Equation

　　INDEX