8. Conclusion

To generate thermal plasmas, there are three main types of torches (or techniques):

• inductively coupled radiofrequency plasmas;

• blown arc torches;

• the transferred arcs.

Commercially available radiofrequency torches operate between 30 and 400 kW. Their main advantages are:

• to be able to operate with almost all gases, including oxidizing gases;

• to have flow rates 10 to 20 times lower than those of blown arc torches and, therefore, residence times 10 to 20 times longer;

• not to have electrodes whose wear pollutes the plasma gases.

These torches are mainly used for spheroidization-purification...