valokaaresta

Valokaari, also known as an electric arc, is a sustained electrical discharge through a gas that produces light and heat. It occurs when a sufficiently high voltage is applied across two electrodes separated by a gas, causing the gas to ionize and become conductive. This ionization creates a plasma, a state of matter composed of ions and electrons, which glows brightly.

Valokaari has been utilized in various applications throughout history. One of the earliest uses was in arc lighting, where it served as a powerful source of illumination before the advent of incandescent and fluorescent lamps. Arc furnaces are employed in metallurgy for smelting and refining metals, leveraging the intense heat generated by the arc to reach very high temperatures. Welding processes, such as arc welding, use the valokaari to melt and fuse metal components. Plasma cutting also relies on the high-temperature plasma jet of a valokaari to slice through conductive materials.

The characteristics of a valokaari, such as its voltage, current, and temperature, depend on factors like electrode material, gap distance, and the type of gas present. While visually striking, the intense ultraviolet radiation emitted by some valokaari can be harmful to the eyes and skin, necessitating protective measures in industrial settings. The phenomenon is also a critical consideration in electrical safety, as uncontrolled valokaari can cause significant damage and pose a fire hazard.