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Herausgeber: John Wiley & Sons
Kategorie: Wissenschaft und neue Technologien
Sprache: Englisch

Beschreibung

Examines the foundation of pulse power technology in detail to optimize the technology in modern engineering settings Pulsed power technologies could be an answer to many cutting-edge applications. The challenge is in how to develop this high-power/high-energy technology to fit current market demands of low-energy consuming applications. This book provides a comprehensive look at pulsed power technology and shows how it can be improved upon for the world of today and tomorrow. Foundations of Pulsed Power Technology focuses on the design and construction of the building blocks as well as their optimum assembly for synergetic high performance of the overall pulsed power system. Filled with numerous design examples throughout, the book offers chapter coverage on various subjects such as: Marx generators and Marx-like circuits; pulse transformers; pulse-forming lines; closing switches; opening switches; multi-gigawatt to multi-terawatt systems; energy storage in capacitor banks; electrical breakdown in gases; electrical breakdown in solids, liquids and vacuum; pulsed voltage and current measurements; electromagnetic interference and noise suppression; and EM topology for interference control. In addition, the book: * Acts as a reference for practicing engineers as well as a teaching text * Features relevant design equations derived from the fundamental concepts in a single reference * Contains lucid presentations of the mechanisms of electrical breakdown in gaseous, liquid, solid and vacuum dielectrics * Provides extensive illustrations and references Foundations of Pulsed Power Technology will be an invaluable companion for professionals working in the fields of relativistic electron beams, intense bursts of light and heavy ions, flash X-ray systems, pulsed high magnetic fields, ultra-wide band electromagnetics, nuclear electromagnetic pulse simulation, high density fusion plasma, and high energy- rate metal forming techniques.

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Leseprobe

Cover

Series Page

Title Page

Preface

About the Authors

Acknowledgments

Introduction

Chapter 1: Marx Generators and Marx-Like Circuits

1.1 Operational Principles of Simple Marxes

1.2 Impulse Generators

1.3 Effects of Stray Capacitance on Marx Operation

1.4 Enhanced Triggering Techniques

1.5 Examples of Complex Marx Generators

1.6 Marx Generator Variations

1.7 Other Design Considerations

1.8 Marx-Like Voltage-Multiplying Circuits

1.9 Design Examples

References

Chapter 2: Pulse Transformers

2.1 Tesla Transformers

2.2 Transmission Line Transformers

2.3 Magnetic Induction

2.4 Design Examples

References

Chapter 3: Pulse Forming Lines

3.1 Transmission Lines

3.2 Coaxial Pulse Forming Lines

3.3 Blumlein PFL

3.4 Radial Lines

3.5 Helical Lines

3.6 PFL Performance Parameters

3.7 Pulse Compression

3.8 Design Examples

References

Chapter 4: Closing Switches

4.1 Spark Gap Switches

4.2 Gas Discharge Switches

4.3 Solid Dielectric Switches

4.4 Magnetic Switches

4.5 Solid-State Switches

4.6 Design Examples

References

Chapter 5: Opening Switches

5.1 Typical Circuits

5.2 Equivalent Circuit

5.3 Opening Switch Parameters

5.4 Opening Switch Configurations

5.5 Design Example

References

Chapter 6: Multigigawatt to Multiterawatt Systems

6.1 Capacitive Storage

6.2 Inductive Storage Systems

6.3 Magnetic Pulse Compression

6.4 Inductive Voltage Adder

6.5 Induction Linac Techniques

6.6 Design Examples

References

Chapter 7: Energy Storage in Capacitor Banks

7.1 Basic Equations

7.2 Capacitor Bank Circuit Topology

7.3 Charging Supply

7.4 Components of a Capacitor Bank

7.5 Safety

7.6 Typical Capacitor Bank Configurations

7.7 Example Problems

References

Chapter 8: Electrical Breakdown in Gases

8.1 Kinetic Theory of Gases

8.2 Early Experiments in Electrical Breakdown

8.3 Mechanisms of Spark Formation

8.4 The Corona Discharge

8.5 Pseudospark Discharges

8.6 Breakdown Behavior of Gaseous SF6

8.7 Intershields for Optimal Use of Insulation

8.8 Design Examples

References

Chapter 9: Electrical Breakdown in Solids, Liquids, and Vacuum

9.1 Solids

9.2 Liquids

9.3 Vacuum

9.4 Composite Dielectrics

9.5 Design Examples

References

Chapter 10: Pulsed Voltage and Current Measurements

10.1 Pulsed Voltage Measurement

10.2 Pulsed Current Measurement

10.3 Design Examples

References

Chapter 11: Electromagnetic Interference and Noise Suppression

11.1 Interference Coupling Modes

11.2 Noise Suppression Techniques

11.3 Well-Shielded Equipment Topology

11.4 Design Examples

References

Chapter 12: EM Topology for Interference Control

12.1 Topological Design

12.2 Shield Penetrations

12.3 Shield Apertures

12.4 Diffusive Penetration

12.5 Design Examples

References

Index

End User License Agreement

List of Tables

Table 1.1

Table 3.1

Table 3.2

Table 3.3

Table 3.4

Table 4.1

Table 5.1

Table 5.2

Table 7.1

Table 8.1

Table 9.1

Table 10.1

Table 10.2

Table 10.3

Table 10.4

Table 11.1

Table 11.2

Table 11.3

List of Illustrations

Figure I.1

Figure 1.1

Figure 1.2

Figure 1.3

Figure 1.4

Figure 1.5

Figure 1.6

Figure 1.7

Figure 1.8

Figure 1.9

Figure 1.10

Figure 1.11

Figure 1.12

Figure 1.13

Figure 1.14

Figure 1.15

Figure 1.16

Figure 1.17

Figure 1.18

Figure 1.19

Figure 1.20

Figure 1.21

Figure 1.22

Figure 1.23

Figure 1.24

Figure 1.25

Figure 1.26

Figure 1.27

Figure 1.28

Figure 1.29

Figure 1.30

Figure 1.31

Figure 1.32

Figure 1.33

Figure 1.34

Figure 1.35

Figure 1.36

Figure 1.37

Figure 1.38

Figure 1.39

Figure 1.40

Figure 1.41

Figure 1.42

Figure 1.43

Figure 1.44

Figure 1.45

Figure 1.46

Figure 1.47

Figure 1.48

Figure 1.49

Figure 1.50

Figure 1.51

Figure 1.52

Figure 1.53

Figure 1.54

Figure 2.1

Figure 2.2

Figure 2.3

Figure 2.4

Figure 2.5

Figure 2.6

Figure 2.7

Figure 2.8

Figure 2.9

Figure 2.10

Figure 2.11

Figure 2.12

Figure 2.13

Figure 2.14

Figure 2.15

Figure 2.16

Figure 2.17

Figure 2.18

Figure 2.19

Figure 2.20

Figure 2.21

Figure 2.22

Figure 2.23

Figure 2.24

Figure 2.25

Figure 3.1

Figure 3.2

Figure 3.3

Figure 3.4

Figure 3.5

Figure 3.6

Figure 3.7

Figure 3.8

Figure 3.9

Figure 3.10

Figure 3.11

Figure 3.12

Figure 3.13

Figure 3.14

Figure 3.15

Figure 3.16

Figure 3.17

Figure 3.18

Figure 3.19

Figure 3.20

Figure 3.21

Figure 3.22

Figure 3.23

Figure 3.24

Figure 4.1

Figure 4.2

Figure 4.3

Figure 4.4

Figure 4.5

Figure 4.6

Figure 4.7

Figure 4.8

Figure 4.9

Figure 4.10

Figure 4.11

Figure 4.12

Figure 4.13

Figure 4.14

Figure 4.15

Figure 4.16

Figure 4.17

Figure 4.18

Figure 4.19

Figure 4.20

Figure 4.21

Figure 4.22

Figure 4.23

Figure 4.24

Figure 4.25

Figure 4.26

Figure 4.27

Figure 4.28

Figure 4.29

Figure 4.30

Figure 4.31

Figure 4.32

Figure 4.33

Figure 4.34

Figure 4.35

Figure 4.36

Figure 4.37

Figure 4.38

Figure 4.39

Figure 4.40

Figure 4.41

Figure 4.42

Figure 4.43

Figure 4.44

Figure 4.45

Figure 4.46

Figure 4.47

Figure 4.48

Figure 4.49

Figure 4.50

Figure 4.51

Figure 4.52

Figure 4.53

Figure 4.54

Figure 4.55

Figure 4.56

Figure 4.57

Figure 4.58

Figure 4.59

Figure 4.60

Figure 4.61

Figure 4.62

Figure 4.63

Figure 4.64

Figure 4.65

Figure 4.66

Figure 4.67

Figure 4.68

Figure 4.69

Figure 4.70

Figure 4.71

Figure 5.1

Figure 5.2

Figure 5.3

Figure 5.4

Figure 5.5

Figure 5.6

Figure 5.7

Figure 5.8

Figure 5.9

Figure 5.10

Figure 5.11

Figure 5.12

Figure 5.13

Figure 5.14

Figure 5.15

Figure 5.16

Figure 5.17

Figure 5.18

Figure 5.19

Figure 5.20

Figure 5.21

Figure 5.22

Figure 5.23

Figure 5.24

Figure 5.25

Figure 5.26

Figure 5.27

Figure 5.28

Figure 5.29

Figure 5.30

Figure 5.31

Figure 5.32

Figure 5.33

Figure 5.34

Figure 5.35

Figure 5.36

Figure 5.37

Figure 5.38

Figure 5.39

Figure 5.40

Figure 5.41

Figure 5.42

Figure 5.43

Figure 5.44

Figure 6.1

Figure 6.2

Figure 6.3

Figure 6.4

Figure 6.5

Figure 6.6

Figure 6.7

Figure 6.8

Figure 6.9

Figure 6.10

Figure 6.11

Figure 6.12

Figure 6.13

Figure 6.14

Figure 6.15

Figure 6.16

Figure 6.17

Figure 6.18

Figure 6.19

Figure 6.20

Figure 6.21

Figure 6.22

Figure 6.23

Figure 6.24

Figure 6.25

Figure 7.1

Figure 7.2

Figure 7.3

Figure 7.4

Figure 7.5

Figure 7.6

Figure 7.7

Figure 7.8

Figure 7.9

Figure 7.10

Figure 7.11

Figure 7.12

Figure 7.13

Figure 7.14

Figure 7.15

Figure 7.16

Figure 7.17

Figure 7.18

Figure 8.1

Figure 8.2

Figure 8.3

Figure 8.4

Figure 8.5

Figure 8.6

Figure 8.7

Figure 8.8

Figure 8.9

Figure 8.10

Figure 8.11

Figure 8.12

Figure 8.13

Figure 8.14

Figure 8.15

Figure 8.16

Figure 8.17

Figure 8.18

Figure 8.19

Figure 8.20

Figure 8.21

Figure 8.22

Figure 8.23

Figure 8.24

Figure 8.25

Figure 8.26

Figure 8.27

Figure 8.28

Figure 8.29

Figure 8.30

Figure 8.31

Figure 8.32

Figure 8.33

Figure 8.34

Figure 8.35

Figure 8.36

Figure 8.37

Figure 8.38

Figure 8.39

Figure 8.40

Figure 9.1

Figure 9.2

Figure 9.3

Figure 9.4

Figure 9.5

Figure 9.6

Figure 9.7

Figure 9.8

Figure 9.9

Figure 9.10

Figure 9.11

Figure 9.12

Figure 9.13

Figure 9.14

Figure 9.15

Figure 9.16

Figure 9.17

Figure 9.18

Figure 9.19

Figure 10.1

Figure 10.2

Figure 10.3

Figure 10.4

Figure 10.5

Figure 10.6

Figure 10.7

Figure 10.8

Figure 10.9

Figure 10.10

Figure 10.11

Figure 10.12

Figure 10.13

Figure 10.14

Figure 10.15

Figure 10.16

Figure 10.17

Figure 10.18

Figure 10.19

Figure 10.20

Figure 10.21

Figure 10.22

Figure 10.23

Figure 10.24

Figure 10.25

Figure 10.26

Figure 10.27

Figure 10.28

Figure 10.29

Figure 10.30

Figure 10.31

Figure 10.32

Figure 10.33

Figure 10.34

Figure 11.1

Figure 11.2

Figure 11.3

Figure 11.4

Figure 11.5

Figure 11.6

Figure 11.7

Figure 11.8

Figure 11.9

Figure 11.10

Figure 11.11

Figure 11.12

Figure 11.13

Figure 11.14

Figure 11.15

Figure 11.16

Figure 11.17

Figure 11.18

Figure 11.19

Figure 11.20

Figure 11.21

Figure 11.22

Figure 11.23

Figure 11.24

Figure 12.1

Figure 12.2

Figure 12.3

Figure 12.4

Figure 12.5

Figure 12.6

Figure 12.7

Figure 12.8

Figure 12.9

Figure 12.10

Figure 12.11

Figure 12.12

Figure 12.13

Figure 12.14

Figure 12.15

Figure 12.16

Figure 12.17

Figure 12.18

Figure 12.19

Guide

Cover

Table of Contents

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IEEE Press445 Hoes LanePiscataway, NJ 08854

IEEE Press Editorial BoardTariq Samad, Editor in Chief

Giancarlo Fortino

Xiaoou Li

Ray Perez

Dmitry Goldgof

Andreas Molisch

Linda Shafer

Don Heirman

Saeid Nahavandi

Mohammad Shahidehpour

Ekram Hossain

Jeffrey Nanzer

Zidong Wang

Foundations of Pulsed Power Technology

Jane Lehr and Pralhad Ron

Published by John Wiley & Sons, Inc., Hoboken, New Jersey.

Published simultaneously in Canada.

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Library of Congress Cataloging-in-Publication Data is available.

ISBN: 978-1-118-628393

Preface

Pulsed power technology provides conditioned charging profiles for present and future applications requiring high peak power. This book is primarily concerned with providing the concepts, design information, and system techniques for optimizing this profile to the application. The field of pulsed power has been difficult to codify because each high-power application requires specific power sources. This customization, along with the innate interdisciplinary nature of the field, has inhibited comprehensive documentation. This book is meant to be useful for designers of pulsed power sources and the researchers who require them. The book will be valuable for graduate students, studying courses in pulsed power technology, plasma physics and applications, laser physics and technology, high-voltage insulation and power system engineering, measurement and diagnostics, high-power electromagnetics, particle beams, and electromagnetic interference and compatibility.

The authors have spent the bulk of their careers in government research laboratory settings in the design and construction of pulsed power technology and applications and have been heavily involved in the evolution of the field. Both authors have taught academic courses in pulsed power and recognize the deep need for a comprehensive book focused on the fundamental principles of the field. It is our deep conviction that a strong foundation in the fundamental principles – and the history of the field – will provide the future workforce with the necessary skills for emerging applications. This book, with its emphasis on engineering design and construction of pulsed power equipment, is intended for graduate students and practicing engineers with specialization in multiple disciplines, since it establishes a firm foundation in pulsed power components, systems, and measurements. Moreover, we include electromagnetic interference, compatibility, and topology concepts for the purpose of controlling noise and interference for modern designs of the pulsed power system. The book bridges the gap between a textbook for students and a monograph for research scientists. The length of the book is intended to provide in-depth insight into the theory, design, and construction of individual components of pulsed power equipment, but short enough to keep the attention anchored to overall system requirements. This book is illustrated with a large number of equations derived from fundamental concepts, figures, and solved design examples. Foundations of Pulsed Power Science and Technology complements the other books on the subjects of pulsed power: Gennady A. Mesyats, Pulsed Power, Kluwer Academic/Plenum Press, 2005; Paul W. Smith, Transient Electronics: Pulsed Circuit Technology, John Wiley & Sons, Inc., 2002; JC Martin on Pulsed Power, edited by T.H. Martin, A.H. Guenther, and M. Kristiansen, Plenum Press, 1996; S.-T. Pai and Qi Zhang, Introduction to High Pulse Power Technology, World Scientific, 1995; and W. James Sarjeant and R.E. Dollinger, High Power Electronics, TAB Books, 1989.

The entire subject of pulsed power technology is covered in 12 chapters. Each chapter contains a large number of references, to lead the researchers to greater depths in the field. This book is organized such that the Chapters 1–5 describe the “building blocks” of a pulsed power system. Chapters 6 and 7 describe considerations with examples of systems resulting from synergetic integration of individual components. The remaining five chapters describe the vital topics of electrical breakdown in insulators of interest (Chapters 8 and 9), pulsed voltage and current measurements (Chapter 10), and electromagnetic interference, compatibility, and topology for interference control (Chapters 11 and 12).

The following are the salient features of the various chapters:

The design formulas, considerations, and examples of the widely used voltage-multiplying circuits based on the Marx generator are discussed in

Chapter 1

, Marx Generators and Marx-Like Circuits. A number of modified configurations of low-inductance Marx generators with capabilities for high-power delivery, fast erection with low jitter, and capability for repetitive pulse generation are discussed. Other circuits, such as the Maxwell Marx and Fitch circuit are introduced even though not widely used.

Chapter 2

, Pulse Transformers, introduces another popular means of voltage multiplication: the Tesla transformer. This chapter also includes a discussion of transmission line transformers for modifying high power pulses with minimum distortion, with its special application for impedance matching to the application device.

Pulse forming lines, discussed in

Chapter 3

, receive input from a Marx generator or Tesla transformer, having capabilities to deliver gigawatts of power in a very short rise time and a flat-top. The various configurations of PFL, such as coaxial lines, striplines, Blumleins, stacked Blumleins, radial lines, helical lines, and spiral generators, are covered. The optimization of PFL design from the viewpoints of maximum charging voltage, maximum power delivery, choice of dielectric, and dielectric strength dependence on charging time are illustrated with solved design examples.

The design considerations and performance parameters of self-triggered and externally triggered

spark gap switches

to transfer the energy to the load at high efficiency with minimum distortion in waveform are covered in

Chapter 4

. A review of spark gap configurations, trigger geometries, trigger modes, and salient features of specialized spark gaps like krytrons, burst mode gaps, and radioisotope-aided gaps is included. Design examples are provided for calculation of inductive rise time, resistive rise time, and a rough estimation of number of spark channels.

Chapter 5

describes a variety of

opening switches

that are a critical component of inductive energy storage systems. An exhaustive coverage of opening switches, their configurations, and performance are discussed at length. The subject covered in this chapter is taken largely from the NRC Report “Opening Switches in Pulsed Power Systems,” Rep.TR-GD-007, by P.H. Ron & R.P. Gupta.

Chapter 6

on multigigawatt pulsed power systems describes advanced systems with capabilities to deliver single or repetitive pulses at very high peak power levels. The major system categories are cascaded capacitor storage, cascaded inductor storage, magnetic pulse compression schemes, inductive cavity cells, and induction linacs. Some well-known machines comprised of fast Marx generators, fast pulse forming lines, and multichannel spark gaps are discussed at greater length, because of their historical importance and the relevance to the evolution of modern-day pulsed power systems.

Chapter 7

, Energy Storage in Capacitor Banks, the theoretical, practical, and safety aspects involved in the design and construction of high current or energy storage capacitor banks are discussed. Capacitor banks are used for the delivery of large energy in the microsecond regime. The capacitor bank discharges have wide ranging applications in plasma heating, high magnetic field generation, and electromagnetic propulsion.

Chapter 8

, Electrical Breakdown in Gases, gives basic concepts of the kinetic theory of gases and ionization. The early experiments of Paschen and Townsend are described as well as insight into the fundamental mechanisms of electrical breakdown of gases. Pseudospark discharge and corona phenomena are also introduced. The techniques of optimum utilization of insulation by providing intermediate electrodes into electrically weak cylindrical and spherical geometries are discussed at depth. Practical hints are given for deriving maximum benefit out of SF

gas and its mixtures with other gases.

Chapter 9

deals with the properties of electrical insulation and electrical breakdown in solids, liquids, and vacuum. The breakdown mechanisms in the above dielectrics and practical techniques to be adopted for enhancing insulation performance are discussed. The important topics of partial discharges and electrical trees, which govern long-term performance of solid dielectrics, behavior of liquids for PFL insulation, and vacuum in application devices, and the theory of surface flashover and some mitigation techniques are described.

The concepts and techniques for

pulsed voltage and current measurements

, which necessarily involves the accurate scaling down of parameters without distortion of pulse shape, are discussed at great depth in

Chapter 10

. The electro-optical and optoelectronic techniques, which possess high immunity to intense EMI, are introduced.

The topic of

Chapter 11

electromagnetic interference and compatibility, is important because of the intense radiated electromagnetic fields generated by the operation of the pulsed power system. This radiation may damage equipment or cause inaccurate measurements or even operation because of extraneous ground loops. After discussing the theory of fundamental mechanisms of capacitive coupling, inductive coupling, common impedance coupling, and radiative coupling responsible for electromagnetic interference, the practical methods of incorporating protection techniques such as shielded cables, power line and signal line filters, isolation transformers, effective earthing, and shielded enclosures are discussed at length.

Techniques required for high frequencies are introduced in

Chapter 12

, EM Topology for Interference Control. Multiple, nested shields in complicated geometric shapes may be incorporated to enable the safe and reliable operation of electronic systems from high interfering levels in harsh environments. To maintain high shield integrity in the presence of numerous shield surface discontinuities requires specialized techniques in the various protection zones and high standards of connections between the penetrating devices and shield.

Jane Lehr

Prahlad Ron

About the Authors

Jane Lehr received the Bachelor of Engineering degree from Stevens Institute of Technology and the Ph.D. degree in Electrical Engineering from New York University in 1996 under the supervision of Professor Erich Kunhardt. Dr. Lehr joined the University of New Mexico's Electrical and Computer Engineering faculty in 2013 after spending 12 years at Sandia National Laboratories in the Pulsed Power Sciences Center. She served 5 years at the Air Force Research Laboratory's Directed Energy Directorate studying ultra-wideband high-power electromagnetics and repetitive pulsed power where she was awarded the USAF-wide Basic Research Award in 2001. Dr. Lehr's research interests are in all aspects of high-power electromagnetics, pulsed power, high-voltage engineering, and the physics and application of electrical breakdown in vacuum, gases, and liquids. Dr. Lehr is a Fellow of the IEEE.

Dr. Lehr served as President of the IEEE Nuclear and Plasma Sciences Society in 2007 and 2008. She has served the Society in a number of roles since then and currently serves as the Chair of the NPS Society Fellow Evaluation Committee. She has served on the Administrative Committees for both the Nuclear and Plasma Science and the IEEE Dielectric and Electrical Insulation Societies. She has served as an Associate Editor of the IEEE Transactions on Dielectrics and Electrical Insulation, Guest Editor of the IEEE Transactions on Plasma Science, and on the IEEE Technical Activities Board Publications Committee. Dr. Lehr received the IEEE Shea Distinguished Member Award in 2015 and the IEEE Region 6 Award for Leadership in 2001. She was named an Outstanding Woman of New Mexico and has been inducted into the New Mexico Hall of Fame for her technical accomplishments and volunteer activities serving her local community.

Prahlad Ron was born in 1939 in Dharwad, Karnataka, India. He obtained his Bachelor of Engineering degree from Pune Engineering College, India, in 1961. He was the winner of the Homi Bhabha Award for top performance in electronics engineering. He joined the Bhabha Atomic Research Centre (BARC) in 1962. He obtained the M. Sc. (Engg.) degree from the University of Manchester, UK, in 1969 and a Ph.D. from the Indian Institute of Science, Bangalore, India, in 1984.

At BARC, Dr. Ron specialized in the design and development of high-voltage equipment for carrying out applications, such as (a) electron beam processing for melting and welding in vacuum., (b) industrial electron beams for radiation processing in atmosphere, (c) pulsed power technology for production of nanosecond multigigawattt electron beams, flash X-rays, and EMP testing, (d) pulsed high magnetic fields for magnetization, demagnetization, and magnetoforming, and (e) electromagnetic interference simulation and protection technology. Dr. Ron led a team of engineers, who successfully carried out garter spring repositioning in the nuclear power reactors at Narora and Kakrapar. Under his leadership, electron beam processing plants based on Cockcroft-Walton multipliers and RF Linacs were successfully developed for industrial applications.

Dr. Ron served as Head of the Accelerator and Pulsed Power Division of BARC from 1992–2001. He was a visiting scientist at Queen Mary College, London, UK in 1970 working on electrical breakdown and at the National Research Council in Ottawa, Canada in 1985 and McGill University, Montreal, Canada, in 1987 working on pulsed power technology. He taught a graduate course in pulsed power technology from 1996 to 2000 at the Devi Ahilya University in Indore, India. Dr. Ron was the Steering Committee Chairman of the Electron Beam Centre in Kharghar, New Bombay, to carry out radiation processing of polymers. He was Chair of the Atomic Energy Regulatory Board's Design Safety Review Committee for the construction of particle accelerators in India. He was Chairman of the Engineering Design Committee for the conversion of BARC's 5.5 MV van de Graff generator into a 7 MV folded tandem ion accelerator. He was a member of the following councils for the Department of Atomic Energy: (a) Trombay Council at BARC, (b) CAT Council, Center for Advanced Technology, Indore, Madhya Pradesh, India, and (c) Cyclotron Council, at Variable Energy Cyclotron Centre, Calcutta, West Bengal, India.

Acknowledgments

The authors are grateful to the large community in pulsed power whose works form the basis for this book. The authors are indebted to Dr. D.V. Giri, ProTech, California, and the great late Dr. Carl Baum, Air Force Research Laboratory, Directed Energy Directorate, and the University of New Mexico for their encouragement, valuable guidance, and constructive suggestions.

JML is grateful to Ian D. Smith of L-3 Communications for an in-depth review of the breakdown scaling formulas; Keith Hodge and Zachariah Wallace of Sandia National Laboratories; University of New Mexico colleagues Chuck Rueben for lessons and Edl Schamiloglu for advice; Jon Cameron Pouncey for commentaries and encouragement; and Mark, for technical assistance and moral support, and to the memory of Lucius J. Lehr, my magnus opus, who is dearly loved.

PHR is grateful to Dr. R. Chidambaram Scientific Advisor, Government of India and former chairman, Department of Atomic Energy and Dr. Anil Kakodkar, Homi Bhabha Chair and former chairman of the Department of Atomic Energy and Dr. S. Bhattacharjee, ex-Director, Bhabha Atomic Research Center (BARC), for their support; Dr. Raj Gupta for providing visiting fellowship grants; the following staff members of the Accelerator and Pulse Power Division (APPD) of BARC: Mr. S.H. Kamble, Mrs. Supriya Barje, Dr. G.V. Rao, Mrs. Geeta Patil, and Miss Poornalaxmi for the preparation of typescripts; his wife, Asha, for providing a loving home environment, thus enabling long concentrated working hours on this book; and also Nitin and Sangeeta and Nilesh and Monica for their cooperation.

Introduction

Pulsed power technology is an area of interest to physicists and engineers in fields requiring high voltages and large currents. Modern pulsed power runs the gamut from its historical roots in flash radiography, X-ray generation, and the simulation of weapons effects, such as nuclear electromagnetic pulse (EMP), to packaged pulsed power for directed energy weapons and biological and medical applications. New applications and techniques continue to emerge.

Pulsed power has traditionally been described as the gradual accumulation of energy over a relatively long timescale and the subsequent compression into pulses of high instantaneous power for delivery in the required form to a load. This process is illustrated in Figure I.1, and is discussed in Chapter 3. Depending on the application, the slow accumulation of energy may be over minutes, such as for charging large capacitive energy store, or milliseconds for systems operating in a repetitive burst mode. The fast discharge is usually less than tens of microseconds but may be measured in tens of picoseconds.

Figure I.1 Pulsed power may be represented schematically as a series of power conditioning stages that increases the peak power while decreasing the pulse width. This technique is known as pulse compression.

Pulsed power generally falls within the following range of parameters:

Energy per pulse

1–10

Peak power

–10

Peak voltage

–10

Peak current

–10

Pulse width

−10

–10

−5

This explanation, however, does not capture the two key elements of the field: the exploitation of the time dependence of electrical breakdown on insulating materials and the specifics of the load requirements.

The observation that electrical breakdown of insulators – be it gas, liquid, or solid – occurs at higher electric fields at shorter pulse durations was well known before the “birth” of pulsed power in the United Kingdom in the late 1950s. Definitive work on electrical discharges in gases and the mechanisms leading to electrical breakdown was performed in the first half of the twentieth century, starting with Townsend's experiments on current growth in low-pressure gases and its relation to ionization. The invention of the Marx generator, patented in 1923, allowed the generation of substantially higher voltages with shorter pulse durations than previously available. The streamer mechanism of electrical breakdown of gases was proposed in the 1940s and seminal work was performed by Loeb, Meek, Craggs, and Raether. At the same time, Llewellyn-Jones and Davies, as well as Raether, continued to advance the understanding of the Townsend breakdown mechanism. The focus, however, was on physics and scant attention was paid to the increased breakdown strength of insulators upon application of pulses of short duration. Even in the very thorough, modern text, Gas Discharge Physics by Yu. Raizer [1], the time dependence of electrical breakdown is rarely mentioned.

The integral nature of the time dependence of electrical breakdown to pulsed power is illustrated in an anecdote relayed by Goodman [2] and Martin [3]. The Atomic Weapons Research Establishment (AWRE) in the United Kingdom had acquired a used electron accelerator that was being used to radiograph explosive events. The radiographs were somewhat blurred and a better resolution was needed. The conventional option was to increase the accelerator beam current by three orders of magnitude – an enormously expensive option. Martin proposed an alternative concept of a high-voltage (∼6 MV), high-current (∼50 kA) accelerator lasting for 30–50 ns exploiting the time dependence of electrical breakdown. The second option was chosen on the basis of cost, and, with its success, pulsed power was born. Martin and his colleagues went on to develop a number of high peak power devices, and, along the way, an empirical relation for the time dependence of insulator breakdown that had the general form:

where F is the average electrical breakdown field, t is the charge time, A is the area, and a, b, and k are constants that depend on the insulating material. These empirical relations allowed electrical breakdown to be predicted and therefore exploited, and are discussed in detail in Chapter 3. The scaling relation clearly shows that higher breakdown electric fields are attained with shorter charge and discharge times. Thus, using the pulse compression scheme illustrated in Figure I.1 permits the generation of high peak power. An in-depth history of these early developments can be found in the article by Smith [4]. Much of the material presented here is derived from work done in the United States and the United Kingdom. Pulsed power was independently and simultaneously developed in the former Soviet Union and is well documented by Mesyats in the English translation of his incredibly detailed book Pulsed Power [5].

Pulsed power technology, simply stated, is the technique and equipment required to adapt the power characteristics of the prime power source to the electrical requirements of the load. Pulsed power in the context of power conditioning captures the quintessence since significant efforts must be made to optimize and specify the power demand. In the preface to the Pulsed Power Monograph series [6–8], Magne (Kris) Kristiansen and Art Guenther describe pulsed power as “special power conditioning for specific applications.” This statement captures both the inextricable link between pulsed power and the application and their uniqueness. In applications requiring high peak power, pulsed power is a low-cost power conditioning technique. Electrical efficiency is increased by delivering the power in a specific optimal form – the “art” of pulsed power. Pulsed power provides unique solutions to certain physics applications.

Based on the above, the following succinct description of pulsed power is proposed:

Pulsed power is a special power conditioning technique that transforms the characteristics of the prime energy source to the electrical requirements of the load. Energy from a primary source is accumulated over a relatively long time scale and compressed into pulses of high instantaneous power. Several stages may be needed to fully exploit the time dependence of breakdown of insulating materials to deliver energy with the required time dependence and amplitude for the application. The resulting peak power delivered to the load has a large ratio of instantaneous-to-average power.

Recognizing pulsed power as special power conditioning, the breadth of applications and the wide variety of implementation imply an overwhelming amount of knowledge is needed to participate. Certainly, this is true in part, but a large user-facility or a high-performance system is rarely designed by a single engineer. Our premise in choosing material for this book is that a strong foundation in fundamental principles – using realized systems as examples – provides a better perspective for the wide number of applications a pulsed power engineer should expect to encounter over a career. In modern times, it is rare that a pulsed power engineer spends an entire career on a single application. In general, an in-depth treatise on applications is avoided to highlight this and instead the focus is on the foundations of pulsed power technology on which most systems are built. Many of the references in this book are old, which is a reflection of fundamental nature of this book, but modern references are included where appropriate.

While traditional applications of pulsed power are still relevant and continue to incorporate advances in technology, a host of new applications with very different operational requirements are emerging. For this reason, we chose to avoid application-driven pulsed power and focus on the fundamentals to provide a strong technical foundation for the next generation, as well as to document the many innovations achieved thus far. It is our belief that once the basics are mastered, they can be combined in any number of ways to create the specified output. The dimensional scale of the equipment may be vastly different but a focus on the fundamentals allows the similarities to be seen. For example, the Marx bank was invented almost a century ago, but continues to play an integral part in many systems. The basic Marx architecture is very versatile: It has been used with solid-state switches to produce a few hundred volts and is used exclusively to produce tens of megavolts, and it stores energy ranging from joules to kilojoules. It is the basis for trigger generators as well as lightning simulators. Marx generators are used exclusively as the energy storage stage of multigigawatt pulsed power systems and voltages over 18 MV have been produced [9]. However, the fundamental circuit architecture used to produce a 10 J per pulse, 200 kV peak voltage Marx generator that is only 15 cm long [10] is also configured into a bank of Marx generators that yields 5 MV, requires a robust mechanical support, and powers a current source. While is it obvious that the application of these two voltage sources are vastly different, their basic operation is the same.

Sources of Information

The dissemination of information related to pulsed power has been a low priority for much of its history and this may be attributed not only to its initial rapid growth but also to its initial use for military applications. Thus, much of the early progress was preserved primarily in reports and internal memoranda and passed informally throughout the community. Copies of these early reports are increasingly difficult to find, with the exception of Carl Baum's Note Series. The Note Series was started in early 1964 by R.E. Partridge, a technical staff member at Los Alamos National Laboratory, to document the rapid progress in the simulation of the nuclear-generated effects. The Note Series recorded both simulation technology (largely pulsed power) and measurement techniques. The Note Series quickly passed into the care of Carl Baum and now stands at over 2000 documents, most of which are available electronically (The Note series is maintained by the Summa Foundation and notes are available from http://www.ece.unm.edu/summa/notes/).

As an academic aid, Texas Tech University and the Air Force Weapons Laboratory (now called the Air Force Research Laboratory Phillips Research site), under the leadership of Kristiansen, created the Pulsed Power Lecture Series. Forty-nine lectures were given and 35 of these leading researchers wrote a self-consistent treatise on their specialty. Later, Kristiansen, along with Art Guenther, began a book series in the category of Advances in Pulsed Power Technology. This series started with two books on high-power switching [6,7]. The third book was a collection of the internal memoranda and high-voltage lectures documenting the work of Charlie Martin's group at AWRE [8]. Many of the memoranda that comprise this book were also archived in the Carl Baum Note Series.

There are also a number of books that are widely used by some pulsed power technologists. For instance, the two classic texts by Meek and Craggs [11,12] as well as the textbooks by Raizer [1] and Fridman and Kennedy [13] give a thorough treatment of gas discharge physics and electrical breakdown. Cobine [14] contains information on the practical implementation of gas discharges, such as the effects of humidity, which are difficult to find elsewhere. Grover's book [15], which has been republished, is a thorough reference on inductance calculations, and Knoepfel has two books on high magnetic fields [16,17]. The MIT Radiation Series volume, Pulse Generators [18], contains essential information on a variety of pulsed lumped element circuit techniques, which are not included in this book. The volume by Lewis and Wells [19] is another out-of-print book that contains a number of clever transmission line configurations for pulsed circuits that are still relevant today for moderate voltages. Martin credits Lewis and Wells as a source of considerable influence in the early days of pulsed power technology [3].

A primary source of information must be the biannual International Pulsed Power Conference and its proceedings. The first conference was held in Lubbock, Texas, in 1976 to aid the dissemination of information in the emerging field. The next conference was held in 1979 and every other year since. In 1995, the Pulsed Power Conference became sponsored by the IEEE and its publications are now available worldwide through IEEE Explore. To encourage publication in archival, refereed articles, the IEEE Transactions on Plasma Science published the first Special Issue on Pulsed Power Science and Technology in April 1997. Its success led to similar Special Issues with open call for papers published in October of even years. Other conferences are the European-Asian Pulsed Power Conference, held in even years, as well as a variety of other conferences specializing in either specific applications or subtopics. An example of the former is the Electromagnetic Launch Conference; and the latter is the Megagauss Conference, which focuses on the generation and use of high magnetic fields.

The evolution of pulsed power may also be viewed through the two issues of the Proceedings of the IEEE. The first appearance of pulsed power in the Proceedings of the IEEE was a portion of an issue, edited by Pace Van Devender, which included the classic paper by Martin [20]. Other review articles exist [21]. More recently, Edl Schamiloglu and Robert J. Barker devoted an issue of the Proceedings of the IEEE to applications of pulsed power [22]. Through this prism the evolution and expansion of pulsed power is apparent.

References

Yu. P. Raizer,

Gas Discharge Physics

, Springer, 1991.

M.J. Goodman, High Speed Pulsed Power Technology at Aldermaston, in

J.C. Martin on Pulsed Power

, in T.H. Martin, A.H. Guenther, and M. Kristiansen, eds., Plenum Press, New York, 1996.

J.C. Martin, Brief and Probably Not Very Accurate History of Pulsed Power at the Atomic Weapons Research Establishment Aldermaston, in

J.C. Martin on Pulsed Power

, in T.H. Martin, A.H. Guenther, and M. Kristiansen, eds., Plenum Press, New York, 1996.

I.D. Smith, The Early History of Western Pulsed Power.

IEEE Trans. Plasma Sci.

, Vol.

, No. 5, pp. 1585–1609, 2006.

G.A. Mesyats,

Pulsed Power

, Kluwer Academic, 2005.

A. Guenther, M. Kristiansen, and T. Martin, eds.,

Advances in Pulsed Power Technology: Vol. 1: Opening Switches

, Plenum Press, New York, 1987.

G. Schaefer, M. Kristiansen, and A. Guenther, eds.,

Advances in Pulsed Power Technology: Vol. 2: Gas Discharge Closing Switches

, Plenum Press, New York, 1990.

T.H. Martin, A.H. Guenther, and M. Kristiansen, eds.,

Advances in Pulsed Power Technology: Vol. 3: J.C. Martin on Pulsed Power

, Plenum Press, New York, 1996.

K.R. Prestwich and D.L. Johnson, Development of an 18 Megavolt Marx Generator.

IEEE Trans. Nucl. Sci.

, Vol.

16, Part II

, No. 3, p. 64, 1969.

M.V. Fazio and H.C. Kirbie, Ultracompact Pulsed Power.

Proc. IEEE

, Vol.

, No. 7, pp. 1197–1204, 2004.

J.M. Meek and J.D. Craggs,

Electrical Breakdown of Gases

, Clarendon Press, Oxford, 1953.

J.M. Meek and J.D. Craggs, eds.,

Electrical Breakdown of Gases

, John Wiley & Sons, Inc., 1978.

A. Fridman and L.A. Kennedy,

Plasma Physics and Engineering

, Taylor & Francis Publishing, 2004.

J.D Cobine,

Gaseous Conductors: Theory and Engineering Applications

, Dover Publications, Mineola, NY, 1941 (and also 1958).

F.W. Grover,

Inductance Calculations Working Formulas and Tables

, Dover Publications, Mineola, NY, 1946 (and also 1973).

H.E. Knoepfel,

Magnetic Fields

, John Wiley & Sons, Inc., 2000.

H.E. Knoepfel,

Pulsed High Magnetic Fields

, North Holland Publishers, 1973.

G.N. Glasoe and J.V. Lebacqz,

Pulse Generators

, McGraw-Hill, 1948.

I.A.D. Lewis and F.H. Wells,

Millimicrosecond Pulse Techniques

, Pergamon Press, 1959.

J.C. Martin, Nanosecond Pulse Techniques.

Proc. IEEE

, Vol.

, No. 6, pp. 934–945, 1992.

I.R. McNab, Developments in Pulsed Power Technology.

IEEE Trans. Magn.

, Vol.

, No. 1, pp. 375–378, 2001.

E. Schamiloglu and R.J. Barker, “Special Issue on Pulsed Power: Technology and Applications,” Proceedings of the IEEE, Volume: 92 Issue: 7, pp 1011–1013, 2004.

1Marx Generators and Marx-Like Circuits

The simplest and most widely used high-voltage impulse generator is the device Erwin Marx introduced in 1925 for testing high-voltage components and equipment for the emerging power industry. The basic operation of a Marx generator is simple: Capacitors are charged in parallel through high impedances and discharged in series, multiplying the voltage. This simplicity, however, is somewhat misleading: The design of a Marx generator, when stray reactance is included and reliability and precise timing are needed, can be incredibly complex.

This chapter discusses the principles of operation and overall performance of Marx generators. For instruction, the design formulas for simple Marx generators based on their equivalent circuits are given in considerable detail. Some aspects are highlighted in the discussion of modified Marx configurations. The importance of overvoltages to Marx operation, as well as advanced triggering techniques, are reviewed. Various aspects of Marx generators such as electrical insulation, delay time and jitter, and the selection of components are discussed. A rigorous analysis is performed for pulse shaping using resistors, which is common in impulse generators.

1.1 Operational Principles of Simple Marxes

A Marx generator is a voltage-multiplying circuit that charges a number of capacitors in parallel and discharges them in series. The process of transforming from a parallel circuit to a series one is known as “erecting the Marx.” In the common parlance, a “stage” is comprised of energy storage and switch. The energy storage elements are usually one or more capacitors, but pulse forming networks or transmission lines may also be used. The switches are almost always gas-insulated spark gaps, with varying sophistication, but other types of switches with low leakage current may be used. A careful evaluation of the role of overvoltage on the switches, however, is recommended.

Figure 1.1 shows two simple ladder-type Marx generators, where a number N of capacitors with a capacitance value C0 are charged in parallel through charging resistors R to a voltage V0 and discharged in series through the spark gaps, producing an open-circuit voltage VOC. The resistors play a dual role: During the charge cycle, the capacitors charge through the resistors on one side while the other completes the circuit to ground. During the discharge cycle, the resistors provide a high-impedance path, forcing the current through the spark gap. The resistance values are chosen sufficiently high to limit the current through the resistors and R ∼ few kΩ to a few ∼ MΩ is sufficient. The charge and discharge cycles and the erection of the Marx are treated separately. Inductors may also be used as isolation impedances.

Figure 1.1 Ladder-type Marx generators may either (a) preserve the polarity of the charging voltage or (b) invert it.

The circuit of Figure 1.1a is an implementation that produces an output with the same polarity as the charge voltage. The advantage of this circuit is the elimination of a switch if the load can tolerate a modest DC voltage during the charge cycle. However, if the first switch is a triggered spark gap, as the Marx erects, a high-voltage transient is introduced into the trigger circuit. This issue is resolved in the circuit of Figure 1.1b. The first spark gap is at ground potential, making the choice of a trigatron as the triggered switch particularly attractive as the trigger pin may be embedded directly into the grounded electrode. The polarity of the output voltage is inverted from the charging polarity.

1.1.1 Marx Charge Cycle

During the charge cycle, the Marx charges a number of stages, N, each with capacitance C0 to a voltage V0, through a chain of charging resistors R, as shown in Figure 1.2.

Figure 1.2 The Marx circuit during the charge cycle. Larger stage capacitances require longer charge times.

The capacitors do not charge instantaneously, but do charge at different rates and sequentially. The time to charge the nth stage with a DC source is given approximately by Fitch [1] and validated by a rigorous analysis by Swift [2], as

(1.1)

It is often advantageous to minimize the charge time TM of Marx, which may be done by using a constant current-charging source. The Nth stage is the last to reach the full charge voltage, and the minimum charge time may be determined by the acceptable difference in charge voltage between the first and Nth (last) stage, illustrated in Figure 1.2, and given by [3]

(1.2)

Given sufficient time, the last stage will charge to the full charge voltage V0. However, the charge time determines the time of electrical stress on the insulation of the Marx, increasing the probability of unintentional insulation failure. Thus, minimizing the time to charge the Marx increases the reliability in highly stressed designs (Figure 1.3).

Figure 1.3 The difference in charge voltage ΔV between the first and Nth stage capacitor for a given Marx charge time TM charged with a constant charging current. The acceptable level of ΔV determines the minimum charge time

Moreover, during Marx erection, as the each stage is switched, the stored energy in that stage begins to discharge through the resistors R on each side with a time constant:

(1.3)

Energy dissipated in the resistor chain is energy lost to the load and contributes to inefficiency. The discharge time of the Marx is load dependent and should be kept short compared to for maximum extraction of energy and generator efficiency.The maximum energy stored in the Marx is

(1.4)

where (NC0) is the parallel combination of the stage capacitance. The actual value is reduced from this maximum because of the reduced charge voltage on the upper stages and the energy lost to the resistors during the charge process.

1.1.2 Marx Erection

The Marx erection is the process of sequentially closing the switches to reconfigure the capacitors from the parallel charging circuit to the series discharge circuit. Marx erection is initiated when a spark gap fires resulting in an increased voltage across the remaining stages. The spark gap is said to be overvolted when the voltage exceeds its DC self-breakdown value. Sufficient spark gap overvoltages are critically important to reliable operation of the Marx.

Any switch in the Marx generator can initiate the erection process, but the maximum output voltage is ensured when the first spark gap initiates the discharge and fires each successive stage. Nonsimultaneity in the firing of spark gaps reduces the amplitude of the output voltage and distorts the waveform, as shown in Figure 1.4.

Figure 1.4 Sequential Marx erection minimizes pulse distortion and maximizes voltage.

Each switch contributes its delay time and jitter to the Marx erection time and its overall jitter. Fast, reliable Marx erection requires that large overvoltages appear on each stage during discharge. The overvoltage as the Marx erects aids in minimizing the switch jitter, but triggering methods may also be used. As Marx generators were used as primary energy storage for very high peak power applications, it was found the process of erecting a Marx is not necessarily straightforward as stray capacitances may limit the achievable stage overvoltage, the details of which are discussed in Section 1.3. Here, all stray impedances are neglected, and the erection of an ideal Marx is examined.

1.1.2.1 Switch Preionization by Ultraviolet Radiation

A convenient method of ensuring low jitter in simple Marx generators is to use the ultraviolet light generated by the firing of the first spark gap to trigger the next stage. The firing of the second stage generates ultraviolet light that aids the erection of the next stage and the Marx erects in a cascade fashion. The circuits of Figure 1.1 may be reconfigured as shown in Figure 1.5 so that the switches are arranged in line-of-sight. The spark gaps are often inserted into a pressurized gas column with the remaining components insulated with oil. This easily fabricated Marx can produce hundreds of kilovolts and erect reliably.

Figure 1.5 A Marx circuit arranged to allow the ultraviolet light generated by the closing of a spark gap to preionize the other spark gaps. The solid line represents a cylindrical support for the spark gaps and the resistors may be wound around the cylinder to connect the capacitors.

1.1.2.2 Switch Overvoltages in an Ideal Marx

Switch overvoltages during erection can be investigated with the aid of Figure 1.6 where, for simplicity, an ideal Marx has infinitely large charge resistors that draw no current. The remaining lossless circuit is a string of capacitors. Each stage capacitor C0 is charged to V0. Note that in this model, the voltages across each spark are equal and represented by Vg.

Figure 1.6 A circuit model for an ideal Marx shows how the erection sequence overvolts the gaps.

The unfired Marx draws no current and VOC = 0. Applying Kirchoff's voltage law (KVL) to each stage, the voltage across each spark gap is equal in magnitude and opposite in sense to the stage capacitor voltage. When the first spark gap fires, its voltage goes to zero and the voltage at its upper node becomes the stage voltage V0. The Marx remains unfired and the voltage is redistributed across the remaining unfired spark gap changing from V0 to a higher value, determined by the number of switches that have fired. Using KVL,

(1.5)

The firing sequence is given by the following [4]:

Before firing, voltage on first gap