Plasma torches

A plasma torch (also known as a plasma arc, plasma gun, or plasma cutter) is a device for generating a directed flow of plasma. The plasma jet can be used for applications including plasma cutting, plasma arc welding, plasma spraying, and plasma gasification for waste disposal.

Thermal plasmas are generated in plasma torches by direct current (DC), alternating current (AC), radio-frequency (RF) and other discharges. DC torches are the most commonly used and researched, because when compared to AC: “there is less flicker generation and noise, a more stable operation, better control, a minimum of two electrodes, lower electrode consumption, slightly lower refractory [heat] wear and lower power consumption”.

In a DC torch, the electric arc is formed between the electrodes (which can be made of copper, tungsten, graphite, molybdenum, silver etc.), and the thermal plasma is formed from the continual input of carrier/working gas, projecting outward as a plasma jet/flame (as can be seen on the right). In DC torches, the carrier gas can be, for example, either oxygen, nitrogen, argon, helium, air, hydrogen; and although termed as such, it does not have to be a gas (thus, better termed a carrier fluid).

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