The high current and energy technologies are widely utilized in various fields. For example, they are needed for the transportation and control of the high power in the electric power field, the generation of a state of high energy density in the industrial field, and so on. Furthermore, a high functionalization of the technologies is also progressing as well as an expansion of each field which the technologies are applied. In this review paper, we introduce the latest trends in the high current and energy technologies, with focusing on elemental advancements and applications in the fields of electric power and energy, industrial application, traffic, and medical care.

Metal wires are widely used for arc ignitions in power arc tests on electrical power installations, and their material and thickness are selected variously. However, the material and the thickness of the metal wire are thought to be influential factors in the severity of the power arc test, because they may change the arc duration and the physical characteristics of arc. Therefore it is important to understand the dependence of the severity of the power arc test on the material and the thickness of the metal wire. In this paper, we made the experiment, where arcs were generated in a closed chamber with changing the material and the diameter of the metal wire for arc ignition. By this experiment, we clarified the fusing characteristics for various metal wires, and then studied how the material and the thickness of the metal wire influence the arc energy for the 1st half-cycle of current. As a result of this study, we pointed out a possibility of changing the severity in the power arc test according to the metal wire for arc ignition.

The present paper describes numerical thermofluid simulation results of SF₆, Ar, and Ar/SF₆ arcs in a nozzle space at atmospheric pressure on the assumption of local thermodynamic equilibrium (LTE) condition. It is crucial to investigate fundamentals on arc extinction phenomena by numerical simulation approach as well as experimental approach. Two-dimensional temperature distributions in SF₆, Ar, Ar/SF₆ gas-blast arcs were calculated in a steady state at a direct current of 50A. Furthermore, transient temperature distributions in these arcs were computed under free recovery condition for a fundamental study. We investigated dependences of the gas mixture ratio of SF₆ to Ar and the gas flow velocity on the arc temperature and the arc voltage. The calculated arc voltage in the steady state and the transition of electron density under free recovery condition were compared with those obtained by laser Thomson scattering method in our experiments. As a result, the increasing admixture ratio of SF₆ to Ar and the increasing gas flow velocity shrinks the arc plasma around nozzle throat inlet, leading to the higher arc resistance. Under free recovery condition, the arc plasma decay more rapidly there. Comparison in electron density shows the similar dependence on SF₆ and Ar, while there is still some difference in the absolute value of electron density between the calculation results and experimental results.

A water plasma was generated by DC arc discharge with a hafnium cathode and a cupper anode. Arc fluctuation in water plasma was examined by arc image observation synchronized with voltage measurement. The main parameters that cause arc fluctuation was a feed rate of solution. The dynamic behavior of the arc as a restrike mode has faster fluctuation than the decomposition process in the water plasma. Axial and radial extent of the arc is increased with increasing in the feed rate. Therefore, effective energy of the arc is decreased with increasing in the feed rate. Decomposition rate of the treated material can be improved by controlling the arc fluctuation in the anode nozzle.

A remarkable characteristic of a vacuum arc cathode spot, which can remove an oxide layer, is that it moves across the metal surface. However, the influence of current change to the parameter of the cathode spot on the boundary layer remains unclear. This study elucidated the split process and frequency in order to know the removal process of vacuum arc cathode spot with vapor from oxide layer. Experiments were conducted using an SS400 cathode and a cylindrical copper anode. A high-speed video camera recorded the cathode spot movement with ND (Neutral Density) filter. The obtained images were then analyzed using plasma image processing. As described herein, the number of cathode spots, split frequency, evaporation rate on the surface of boundary layer were measured with changing the current. As a result, the parameter of the cathode spot was normalized by the current density and number. In addition, the cathode spot have appropriate number and area for current continuity. In the case of mean number, the current density becomes the maximum. Moreover, the evaporation rate of oxide layer depends on the current density multiplied by number of cathode spot. However, the evaporation rate does not increase because the current per a cathode spot is very small when the number of cathode spots exceeds the mean number.

For large-scale illumination necessary for emergency, a brightness and light color becomes the problem. The radiation emitted from the arc becomes very high intensity. Some researchers have researched the HID (High-Intensity Discharge) lamp which is one of the arc lamp with mixed metal vapor, and the line spectrum emitted from the metal vapor is used for improvement of color rendering spectrum. The broad spectrum emitted from continuous spectrum is needed for improvement of color rendering spectrum. Previous research has elucidated the spectrum control for the color rendering improvement of the argon arc mixed with scandium vapor. In addition, it is necessary to perform the calculation using the wall-stabilized arc at a uniform the contribution to the temperature distribution which the convection gives it to bell-shaped form in the gas flow-stabilized arc for the axial distance. Therefore, the model of the cope of radiation power and color rendering should be suggested. This research elucidates the contribution to improvement of color rendering on wall-stabilized argon arc affected by current and wall radius. The radiation power and color rendering increases because of temperature increment derived from the current increment (Joule's heating). Thus, improvement of radiation power and color rendering with controlled by the current and wall radius because of the temperature distribution for significant temperature effect on wall-stabilized argon arc.