Contents

Preface

References

Chapter 1

Supershort Avalanches Electron Beam in High-Pressure Gases

Abstract

Introduction

Experimental Setup and Measurement Methods

Experimental Results and Discussion

1. Observed Forms of Discharge in Atmospheric-Pressure Air and Nitrogen

2. Waveforms of the Voltage and the Discharge Current Pulses

3. Waveforms of the SAEB Current Pulses and Their Shift Relative to Those of the Voltage and Discharge Current Pulses

4. Effect of the Collector, Collimator, and Cathode on the Results of the Amplitude and Duration of the SAEB Current Measurements

5. Energy of Electrons of the SAEB

6. Runaway Electrons and X-Ray Emission Behind the Anode Foil at Pressure More Than 0.1 MPa

On the Mechanism of REs Generation

Conclusion

Acknowledgments

References

Chapter 2

On the Effect of Cathode Material in the Generation of Runaway Electron Beams and X-Rays in Atmospheric Pressure Air

Abstract

Introduction

Measurement of Runaway Electron Beams in Atmospheric Pressure Air

Experimental Setup and Measurement Arrangement

Experiments on Setups 1 and 2 with Tubular Cathode

Experiments on Setup 1 with Conical Cathode

Experiments on Setup 3 with Tubular Cathode

Discussion

Conclusion

Acknowledgment

References

Chapter 3

Dual Pulses of Runaway Electron Beam Current During the Subnanosecond Breakdown in Nonuniform Electric Field

Abstract

Introduction

Experimental Setup and Techniques

Experimental Results

Conditions of Appearance of Two SAEB Pulses during a Single Voltage Pulse

REB’s Generation after SAEB at Atmospheric Pressure

Discussion

Conclusion

Acknowledgment

References

Chapter 4

Generation of Supershort Avalanche Electron Beams in SF6

Abstract

Introduction

Experimental Setup and Measurement

Experimental Results on the First Setup and Their Discussions

Experimental Results on the Second Setup and Their Discussion

Experimental Results on the Third Setup and Their Discussion

Voltages across the Gap and REB in SF6 at Different Pressures

Voltages across the Gap and REB in Air at Different Pressures

Comparison between Spectra of RAE Beam in SF6 and in Air

SAEB Parameters for SF6

SAEB Generation Mechanism

Conclusion

References

Chapter 5

Fast Electrons behind Grid Cathode in Nanosecond Discharges in Atmospheric Pressure Air

Abstract

Introduction

Experimental Setup and Measuring Technique

Measurement Results

Electric Field Distribution

Discussion

Conclusion

Acknowledgment

References

Chapter 6

Electron Beams with Currents more than 400A and Width Tunable between 1.0–0.1 ns

Abstract

Introduction

Experimental Setup and Techniques

Results

A. Vacuum Diode Mode

B. Gas Diode Mode

Discussion

Conclusion

Acknowledgment

References

Chapter 7

Techniques and Detectors for Measurement of Subnanosecond and Picosecond Pulses of Electron beam Current, Current through the Discharge Gap and Voltage

Abstract

Introduction

1. Nanosecond and Subnanosecond Pulsers

2. Measuring Equipment

3. Measuring High-Voltage Pulses of Short Duration

3.1. Numerical Experiment

3.2. Measurement Results

3.3. Design of a Voltage Divider Based on Coupled Lines

4. Measurement of Pulses of the Current through the Discharge Gap

5. Measurement of Amplitude and Duration of Supershort Avalanche Electron Beam (SAEB)

5.1. Registration of Picosecond Current Pulses of SAEB

5.2. Registration of Subnanosecond Current Pulses of SAEB

6. Synchronization of Pulses of the SAEB Current, the Discharge Current and the Voltage across the Gas-Filled Diode

6.1. Synchronization of SAEB Current Pulses and Discharge Current Pulses

6.2. Synchronization of SAEB Current Pulses, Discharge Current Pulses and Voltage Pulses

Conclusion

Acknowledgments

References

Chapter 8

X-Rays from Long Laboratory Sparks in Air

Abstract

1. Introduction

2. Laboratory Setup

2.1. High Voltage Impulse Generator

2.2. Spark-Gaps

2.3. Detectors

3. Development of Meter and Microsecond Scale Sparks

3.1. Inception

3.2. Streamer Propagation

3.3. Leader Phase

3.4. Breakdown

4. Occurrence of X-Rays

4.1. Features of X-Rays in Positive Discharges

4.2. Features of X-Rays in Negative Discharges

4.3. Effect of the Peak Voltage and Voltage Rise Time

4.4. Effect of the Gap Configuration

4.4.1. Variation of Electrode Shape in One of the Electrodes

4.4.2. Variation of Gap Distance

4.5. Polarity Asymmetry

4.6. Measurements of Microwave RF Radiation and X-Rays

References

Chapter 9

Generation of High-Energy Electrons and X-Rays in High-Voltage Diffuse Discharges at Atmospheric Pressure with Interelectrode Gaps Up to Tens of Centimeters

Abstract

Introduction

1. Studies of Three-Electrode Systems

1.1. Experimental Equipment

1.2. Electrical Characteristics, High-Energy Electron Beams, and Х-Ray Radiation

1.3. Microstructure of Current Channels

1.4. Physical Model of High-Energy Electrons Generation in Three-Electrode Systems

Forming the Microstructure

Energy Input and Gas Heating in the Microchannels

Thermal Expansion of Microchannels and Decreasing Neutrals Density

Electrons Runaway in the Microchannels with Decreased Gas Density

2. Studies of Discharge in Geometry Rod (Cathode)-Plane

2.1. Experimental Equipment

2.2. Experimental Results

2.3. Physical Model of Discharge

Conclusion

References

Chapter 10

Switches Based on the Open Discharge with Counter-Propagating Electron Beams

Chapter 11

Generation of Wide Aperture Electron Beams in Inert Gases of Middle Pressure

Abstract

1. Introduction

2. Electron Beam Generators Based on Barrier Discharge

2.1. Experimental Set-Up

2.2. Generator Design

2.3. Electrical Scheme

3. Parameters of Electron Beams

3.1. Beam Current Density

3.2. The Beam Structure

3.3. Energy Efficiency of the Electron Beam Generation

3.4. X Ray Generation

4. Application of Wide Aperture Electron Beam for Xenon Laser Pumping

4.1. Methods of Gas-Discharge Media Excitation at Optimal Electron Parameters

4.2. Design of Xe-Laser with a Barrier Discharge

4.3. Recovery of the Discharge Current and the Voltage Across the Acceleration Gap

4.4. Electrical Parameters of the Barrier Discharge

4.5. Visible Luminosity of the Gas

4.6. Laser Parameters

4.7. Optimum Conditions for the Excitation with Fast Electrons

Conclusion

References

Chapter 12

Generation of High-Energy Electrons in the Nanosecond Gas Discharges with a Hollow Cathode

Abstract

1. Introduction

2. Shapes of a Hollow Cathode

3. The Dynamics of the Formation and Development of Transverse Nanosecond Discharges with a Slotted Cathode

3.1. Results of the Experimental Study of Transverse Nanosecond Discharges with a Slotted Cathode

3.2. Dynamics of the Formation and Development of Transverse Nanosecond Discharges with a Slotted Cathode

4. Generation of High-Energy Electrons in Nanosecond Discharges with a Slotted Cathode

4.1. Emission of Electrons from the Cathode and the Maintenance of a Nanosecond Discharge with a Slotted Cathode

4.2. High-Energy Electrons in Nanosecond Discharges with a Slotted Cathode: Formation Mechanisms and Energy Characteristics

4.3. The Motion Modes of Accelerated Electrons in the Discharge Plasma and the Formation of Electron Beams

5. Anisotropy of the Processes of Electronic Excitation in the Nanosecond Discharges with a Hollow Cathode

5.1. Polarization of Atomic Ensembles in the Ionized Gases

5.2. The Effects of Polarization of Spontaneous Emission in the Plasma-Beam Discharges with a Slotted Cathode

5.3. Mechanism of Polarization of Atomic States in the Nanosecond Discharges with a Hollow Cathode

6. Results of the Experimental Study of the Population of the Excited States of Atoms in the Nanosecond Discharges with a Slotted Cathode

6.1. Technique and Methods of Measuring the Concentration of Excited Atoms in the Nanosecond Discharges

6.2. Results of Experimental Study of the Concentration of Metastable Atoms in the Nanosecond Discharge with a Slotted Cathode

6.3. The Role of Metastable Atoms in the Kinetics of Excited Atoms of Nanosecond Discharges with a Slotted Cathode

Conclusion

Acknowledgments

References

Chapter 13

Runaway Electrons in Subnanosecond Discharges in High and Ultra-High Pressure Nitrogen

Abstract

1. Introduction

2. Typical Conditions of Operation of Subnanosecond Switches

3. Transition of Electrons to the RAE Mode at Subnanosecond Pulse Electric Breakdown in High and Ultra-High Pressure Gases

3.1. Experimental Setup

3.2. Experimental Results and Discussion

4. Switching Characteristics of the Nitrogen Discharge Gap in Subnanosecond Time Scale

4.1. Statement of the Problem

4.2. Experimental Setup

4.3. Experimental Results and Discussion

5. Streak Investigations of a Subnanosecond Discharge in High-Pressure Nitrogen

Conclusion

Acknowledgments

References

List of Contributors

Index

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