Cathode Processes in the Mercury Arc

and Voltage.- b. Effect of Circuit Inductance.- c. Effect of Capacity.- 25. Mean Arc Duration ? as Affected by Conditions Inside the Discharge.- a. Effect of Arc Length and Cleanness of Mercury Surface on the Arc Duration ?.- b. Effect of Temperature and State of Aggregation of the Cathode on ? Results of Measurements on an Arc with an Anchored Spot.- c. Effect of a Gaseous Medium on the Stability of the Arc.- d. Stabilizing Effect of a Magnetic Field.- e. Effect of the Method of Exciting the Arc.- 26. Discussion of the Results of Measurements.- B. Oscillational Process in the Cathode Region and the Restoring Mechanism of the Arc.- 27. Voltage Oscillations in the Short Arc.- a. Method of Observation.- b. Oscillations in an Arc with an Anchored Spot.- c. Oscillation Processes in an Arc with the Cathode Spot Moving Freely Over the Mercury.- 28. The Transitional Form of the Arc Discharge.- 29. The Relation Between the Voltage Oscillations and the Cathode Processes in a Short Arc. Instability of the Cathode Drop.- 30. Arc Re-ignition and "Relay-Race" Types of Arc Restoration.- C. The Problem of Arc Stability and How It is Affected by Various Internal Factors.- 31. Physical Features of Possible Ways of Stabilizing the Arc.- a. Mechanism of Arc Stabilization by Cathode Heating.- b. The Nature of the Phenomena Occurring in a Solid-Cathode Arc.- c. The Increase in Arc Stability When the Cathode Spot is Anchored on a Thin Liquid Mercury Film.- d. The Mechanism by Which a Gaseous Medium Affects the Arc.- e. The Mechanism by Which the Arc is Stabilized by a Magnetic Field.- 32. Internal Instability of the Mercury Cathode Arc.- 3. The Focal Structure and the Continuous Decay and Re-formation of the Cathode Spot on a Mercury Cathode.- 33. Fundamental Problems and Methods of Investigating the Cathode Spot.- A. Structure and Behavior of the Cathode Spot on Mercury Under Steady-State Current Conditions.- 34. Investigation of the Structure of the Spot Where It is Anchored at the Boundary of the Region Where a Metal is Wet by Mercury.- 35. Data on the Elementary Cells in the Cathode Spot.- 36. Decay and Division of Elementary Cathode-Spot Cells Under Steady-State Conditions.- 37. Interaction Between Cells and Why They Move Over the Cathode.- 38. Coordination Between Cell Decay and Cell Division. The "Relay-Race" Type of Arc Restoration.- 39. Special Features of the Structure of the Cathode Spot on a Homogeneous Liquid Cathode.- B. How an Arc Discharge is Set Up, and How It Changes from One Steady State to Another.- 40. Setting Up the Steady State of the Arc at a Rate of Current Increase Less Than 108A/sec.- 41. Nature of the Phenomena When the Current Is Increased at a Rate of 108 A/sec or Higher. Transition to a Spark Discharge.- 42. The Essence of the Process Controlling the Current in the Cold-Cathode Arc. The Dynamic Volt-Ampere Characteristic of the Arc.- C. Re-formation of the Cathode Spot in the Steady State and the Role Played in the Process by a Magnetic Field.- 43. General Information on Spot Re-formation on a Cold Cathode.- 44. Model of the Cathode Spot on a Homogeneous Liquid Mercury Cathode.- a. Structure and Fundamental Physical Processes of the Spot.- b. Factors Determining the Stability and Dimensions of the Spot. Effect of the Inherent Magnetic Field of the Arc.- c. Excess Electrons in the Ionization Region of the Arc. Electron Envelope of the Cathode Spot.- d. Simplified Dynamic Model of the Cathode Spot.- 45. The Dominant Role Played by the Magnetic Field in Regular Cathode-Spot Re-formation. The Maximum Field Principle.- 4. Basic Forms of Cathode-Spot Re-formation on a Homogeneous Liquid Cathode.- 46. Problems and Importance of Investigating the Motion of the Spot. Need to Include the Effect of the Inherent Magnetic Field of the Arc.- A. Regular Motion of the Cathode Spot on a Liquid Mercury Cathode.- 47. Direction of the Motion.- a. Theoretical Trajectory of the Spot in an Inhomogeneous Magnetic Field.- b. Experimental Study of the Trajectory of the Cathode Spot in an Inhomogeneous Magnetic Field.- c. The Trajectory of the Cathode Spot as Affected by the Slope of the Magnetic Field Vector Relative to the Cathode.- 48. Rate of Motion of the Spot and New Ways of Finding the Current Density at the Cathode of the Arc.- a. Theoretical Discussion of the Question. Limits of Applicability of the Theory.- b. Results of Measuring the Rate of Motion of the Spot as a Function of the Magnetic Field Intensity and Current.- c. Rate of Motion of the Spot in a Magnetic Field as a Function of the Density of the Gas Medium, and the Motion Inversion Phenomenon.- B. Division of the Cathode Spot and Interaction Between Autonomous Spots.- 49. Fundamental Concepts.- a. The Form of the Cathode Spot and What Factors Determine It.- b. Distribution of the Inherent Magnetic Field of the Arc at the Cathode Spot, and the Role Played by the Components of the Field.- c. Irregularity in the Inherent Field of the Arc and the Role Which It Plays in Regular Spot Division. Effect of an External Field on Division.- 50. Interaction Between the Autonomous Parts of the Cathode Spot Formed by Division.- 51. Distribution of Duration Times of the Autonomous Spots.- a. Method and Observational Errors. The Criterion for Spot Division.- b. Results of Measurements during Directed Motion of the Spot in a Magnetic Field.- c. Results of Measurements in the Absence of an External Field.- 52. Distribution of the Intervals Between Successive Divisions. Frequency of Division of the Cathode Spot.- a. Spot Divisions with Directed Motion in a Strong Magnetic Field.- b. Division of the Spot with No External Field.- c. Artificial Statistical Selection of Observations. The Regular Nature of Cathode-Spot Division on a Homogeneous Mercury Cathode.- d. The Effect Which the Criterion for Division Has on the Results of the Observations.- C. Chaotic Motion of the Cathode Spot on a Homogeneous Liquid Cathode.- 53. Formulation of the Problem of a Possible Relation Between Chaotic Motion and Division of the Spot.- 54. Experimental Proof of the Dominant Role Played by Division in the Chaotic Motion of the Spot on a Homogeneous Liquid Cathode.- Conclusion.- Appendices.- 1. Method of Testing Mass-Produced Mercury Tubes.- 2. Magnetic Anchoring of the Cathode Spot and Protection of the Metal Shell of Mercury Tubes.- 3. Measuring the Amount of Mercury Atomized and Evaporated by the Cathode Spot and the Recoil Forces Experienced by the Cathode.- a. Determination of the Mercury Losses.- b. "Weighing" the Cathode Spot.- 4. Generation of Mercury Drops by the Cathode Spot.- Literature Cited.