8. Conclusion

There are three main types of torch (or techniques) for generating thermal plasmas:

• inductively coupled radiofrequency plasmas ;

• blown-arc torches ;

• transferred bows.

Commercially available radio-frequency torches range from 30 to 400 kW. Their main advantages are :

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

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

• no worn electrodes to pollute plasma gases.

These torches are mainly used for particle spheroidization-purification, the projection of large...