Disclosed are apparatus and method for obtaining energy from high electrical charge density entities. The energy may be received by the conductor of a traveling wave device positioned along the path which the propagating entities follow. Multiple traveling wave devices may be combined. Energy output from a traveling wave device may also be directed to the generation of a subsequent such entity. Thermal energy may also be obtained from an EV.

Energy conversion using high charge density

The increasing importance of electrical contacts in air with micrometer spacing prompted recent experiments on the electrical breakdown behavior of these gaps. The electrical field between the contacts used in one of the experiments was analyzed using finite element analysis to model the electric field. The experimental data on the electrical breakdown voltage could be divided into three regions as a function of the gap spacing. First, at close gap spacing (/spl les/4 /spl mu/m) both the breakdown voltages as well as the electrical fields at the cathode were similar to values measured during the breakdown of vacuum gaps of less than 200 /spl mu/m. Second, at larger gaps (>6 /spl mu/m) the breakdown voltages followed Paschen's curve for the Townsend electron avalanche process in air. Finally, in between these two regions the breakdown values were below the expected values for purely vacuum breakdown or purely Townsend breakdown. The breakdown phenomena have been discussed in terms of field emission of electrons from the cathode and their effect on initiating the observed breakdown regimes.

Electrical breakdown in atmospheric air between closely spaced (0.2 /spl mu/m-40 /spl mu/m) electrical contacts

A new mechanism for the operation of a cathode spot in a vacuum arc, based on ecton processes, is proposed. An ecton is formed by the explosion of the tip of a jet of molten metal as it interacts with plasma. The time of ecton operation is assumed to be limited by the thermal conductivity of the liquid metal. For copper electrodes, the theoretical expressions are derived for the specific mass removal, ion erosion characteristics, current density, and the diameters of craters. The results agree well with the experimental data available.

Ecton mechanism of the vacuum arc cathode spot

Desorbed gases from insulator surfaces may be much more important in flashover initiation than properties of the dielectric surface. Ambient neutral densities, immediately above the insulator surface, in the initial stages of flashover have been calculated to lie in the range from 2×1017/cm3 to 2×1021/cm3 with a mean of about 1×1019/cm3, whether flashover occurred on surfaces in air at atmospheric pressure or in vacuum as low as 10−6 Torr. The evidence presented indicates that, for dc and microsecond pulse voltages, surface flashover is a local, relatively high‐pressure phenomenon. Comparison of field strengths of surface flashover for various insulating materials perpendicular to the electrodes, operating pressures, and voltage waveforms appears to indicate that flashover values range well within an order of magnitude (∼18–80kV/cm). A filamentary nature of the flashover discharge is shown and is consistent with gas breakdown phenomena. Ionization wave front velocities are examined and these compare favorably with those obtained from gaseous breakdown studies.

Vacuum surface flashover: A high‐pressure phenomenon

This paper is an overall review of studies carried out by the authors and some of their colleagues on RF breakdown, Field Emission and RF processing in room temperature electron linac structure. The motivation behind this work is twofold: in a fundamental way, to contribute to the understanding of the RF breakdown phenomenon, and as an application, to determine the maximum electric field gradient that can be obtained and used safely in future e/sup +-/ linear colliders. Indeed, the next generation of these machines will have to reach into the TeV (10/sup 12/ eV) energy range, and the accelerating gradient will be to be of the crucial parameters affecting their design, construction and cost. For a specified total energy, the gradient sets the accelerator length, and once the RF structure, frequency and pulse repetition rate are selected, it also determines the peak and average power consumption. These three quantities are at the heart of the ultimate realizability and cost of these accelerators. 24 refs., 19 figs., 4 tabs.

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Rf breakdown studies in room temperature electron linac structures

Investigations concerning nanosecond processes in vacuum discharges are described The role of explosive processes at the cathode has been established Experimental results concerning breakdown voltage, discharge current temporal behavior, delay time, spark-to-arc transition time, X-ray radiation, and electrode erosion are reported The general characteristics of the fast breakdown process are discussed together with cathode explosions, emission, and erosion

Explosive Processes on the Cathode in a Vacuum Discharge

A fundamental role of microexplosions on the cathode in discharge initiation and development is established on the basis of the author's earlier studies of pulsed vacuum discharges. Upon analyzing some methods of vacuum arc initiation, the conclusion is reached that all of them are based in the end on the occurrence of a microexplosion on the cathode. Self-maintenance of an arc is due to the fact that each preceding microexplosion creates the conditions for appearance of one or a few new microexplosions. It is shown that microexplosions occur in a cyclical manner, i.e. they appear due to fast heating of the cathode microarea and then cease because this area cools in consequence of the decreased current density, the heat conductance, the intensity of electron emission, and evaporation. It is suggested that new microexplosions necessary for self-maintenance of a vacuum arc occur due to the explosion of a metal neck which forms on the detachment of a liquid drop from a point, when a current density of up to l09 A · cm-2 flows through the neck. The drops form due to the high-pressure plasma (up to 109 Pa) that affects the liquid metal. The suggested model explains many wellknown experimental results: the high current density in a cathode spot, the cathode spot random motion, the emission of microdrops from the cathode spot, the threshold arc current, etc.

A Cyclical Explosive Model of the Cathode Spot

A review is presented of recent investigations concerning the effect of cathodes at cryogenic temperatures on the initiation of a pulsed vacuum breakdown. It has been observed that cooling Nb and W cathodes from 300 K to 4.2 K results in a monotonic increase of the critical emission current and the pulsed electric strength of the vacuum gap. This appears to be due to variations of the thermophysical characteristics (resistivity, thermal conductivity and heat capacity) of the cathode on cooling. The superconducting state of an Nb cathode essentially does not affect the vacuum breakdown delay time. Also given are the results of a study of the initiation of a vacuum breakdown between electrodes made of high-temperature superconductors. >

http://ieeexplore.ieee.org/iel1/14/1750/00046305.pdf

G. A. Mesyats

Papers

Explosive Processes on the Cathode in a Vacuum Discharge

A Cyclical Explosive Model of the Cathode Spot

Pulsed electrical discharges in vacuum at cryogenic electrode temperatures