Pulsed Electrical Discharge in Vacuum

This is an up-to-date review of studies in the physics of pulsed electrical discharges in a vacuum. It gives the reader detailed information on the processes occurring at electrodes and in vacuum gaps and on the mechanisms of discharge initiation and development. Modern techniques and equipment are described in detail. Their high temporal and spatial resolution may be used to solve a number of problems concerning the short-term and microscopic aspects of discharges. A summary is given of a great deal of experimental data on the kinetics of vacuum breakdown. The authors used these results to identify a series of steps in the vacuum breakdown phenomenon. They were the first to discover and describe the explosive electron emission phenomenon and to show its fundamental role in the spark and the arc stages of a discharge. The information in this book may encourage the reader to design new experiments. The results presented may be applied to solve specific research or engineering problems.

Contenu

1. Introduction.- 2. Review of Vacuum Breakdown and Discharge Studies.- 2.1 The Electrode Surface in a Vacuum Discharge.- 2.2 Vacuum Insulation, Properties and Breakdown.- 2.3 Kinetics of Vacuum Electrical Breakdown.- 2.4 Field Electron Emission to Vacuum Breakdown Transition.- 2.5 Hypotheses on Vacuum Breakdown Initiation.- 2.6 Spark Stage of Vacuum Breakdown.- 2.7 The Discharge Arc Stage. The Cathode Spot.- 3. Experimental Equipment and Techniques.- 3.1 Electrical Measurement Techniques.- 3.2 Diagnostics of the Radiation that Accompanies Breakdown.- 3.3 Vacuum Equipment.- 3.4 Preparation and Examination of Electrode Surfaces.- 4. Pulsed Nanosecond Breakdown of Vacuum Gaps.- 4.1 Time Characteristics of the Pulsed Vacuum Breakdown.- 4.2 Study of Light Emission at Pulsed Breakdown.- 4.3 Electrode Erosion Studies.- 4.4 Nature of the Discharge Current at Breakdown.- 4.5 Mechanism of Pulsed Breakdown of Vacuum Gaps.- 5. Cathode Processes in a Pulsed Vacuum Discharge.- 5.1 EEE Initiation by High-Density FEE Current.- 5.2 Erosion of Point Cathodes.- 5.3 EEE Current Density Measurements.- 5.4 Microstructure of the Cathode Surface.- 5.5 The Contribution of Droplet Ejection to Cathode Erosion.- 5.6 Pressure in the Emission Zone.- 5.7 Formation of Cathode Microstructure.- 6. Cathode Flare Plasma.- 6.1 Velocity of CF Plasma Expansion.- 6.2 CF Plasma Parameters.- 6.3 EEE Current Effect on the Dynamics of the Plasma Light Emission.- 6.4 A Model for CF Plasma Expansion.- 7. Current Passage in the Spark Stage of Breakdown.- 7.1 Electron Emission from CF Plasma into Vacuum.- 7.2 Electron Emission from CF Plasma, Experimental Studies.- 7.3 Current-Voltage Characteristics of a Single-CF Diode.- 7.4 Dynamics of the CF Electron Emission Boundary.- 7.5 CF Plasma Potential Distribution and Plasma Emissive Properties.- 7.6 Spark Current Between Broad-Area Electrodes.- 8. Formation of New Emission Centers on the Cathode.- 8.1 Mechanisms of New EC Formation Under the Plasma.- 8.2 New EC Formation and Operation Under Cathode Plasma.- 8.3 Screening Effect and Electron Beam Structure in a Diode.- 9. Anode Processes in the Spark Stage of Vacuum Breakdown.- 9.1 Anode Heat Conditions.- 9.2 Surface Structure of the Anode in the Discharge Zone.- 9.3 Formation of Anode Flares.- 9.4 X-Radiation Generated at the Anode.- 10. Fast Processes at DC Breakdown of Vacuum Gaps.- 10.1 Electrical Study of DC Breakdown.- 10.2 Optical Studies.- 10.3 Comparison with Results of Other Investigations.- 10.4 EEE Initiation at DC Breakdown.- 11. Nonstationary Processes in the Vacuum Arc Cathode Spot.- 11.1 The Motion of Vacuum Arc Cathode Spots.- 11.2 Response of the Vacuum Arc to Current Transients.- 11.3 Vacuum Arcs at Threshold Currents.- 11.4 Numerical Simulation of Processes in an Explosive Emission Center.- 11.5 Explosive Electron Emission and the Vacuum Arc Cathode Spot.- 12. Pulsed Electrical Discharge in Vacuum at Cryogenic Electrode Temperatures.- 12.1 Field Electron Emission at Low Cathode Temperatures.- 12.2 Field Emission Current Preceding the Explosion of a Point.- 12.3 Characteristics of the Vacuum Discharge at Cryogenic Temperatures.- 12.4 Vacuum Discharge Between Electrodes Made of High-Temperature Superconductors.- References.