All these engineering concepts are aiming to create the proper flow pattern necessary to insure the stability of the gas discharge in the center of the coil region. Q3 is commonly referred to as "Sheath Gas" that is introduced outside the internal tube mentioned above. The flow pattern of Q3 can be either vortex or straight. The function of sheath gas is twofold. It helps to stabilize the plasma discharge; most importantly, it protects the confinement tube, as a cooling medium. In practice, the selection of plasma gases in an induction plasma processing is first determined by the processing chemistry, i.e., if the processing requiring a reductive or oxidative, or other environment. Then suitable second gas may be selected and added to argon, so as to get a better heat transfer between plasma and the materials to treat. Ar–He, Ar–H2, Ar–N2, Ar–O2, Air, etc. mixture are very commonly used induction plasmas. Since the energy dissipation in the discharge takes places essentially in the outer annular shell of plasma, the second gas is usually introduced along with the sheath gas line, rather than the central gas line. Following the evolution of the induction plasma technology in laboratory, the major advantages of the induction plasma have been distinguished:   These features of induction plasma technology, has found niche applications in industrial scale operation in the last decade. The successful industrial application of induction plasma process depends largely on many fundamental engineering supports. For example, the industrial plasma torch design, which allows high power level (50 to 600 kW) and long duration (three shifts of 8 hours/day) of plasma processing. Another example is the powder feeders that convey large quantity of solid precursor (1 to 30 kg/h) with reliable and precise delivery performance. Nowadays, we have been in a position to be able to numerate many examples of the industrial applications of induction plasma technology, such as, powder spheroidisation, nanosized powders synthesis, induction plasma spraying, waste treatments, etc., However, the most impressive success of induction plasma technology is doubtless in the fields of spheroidisation and nano-materials synthesis. The requirement of powders spheroidisation (as well as densification) comes from very different industrial fields, from powder metallurgy to the electronic packaging. Generally speaking, the pressing need for an industrial process to turn to spherical powders is to seek at least one of the following benefits which result from the spheroidisation process:  Spheroidisation is a process of in-flight melting.