Production of Ultrafine Particles in a Plasma System Having Controlled Pressure Zones

A system for making ultrafine particles, comprising:

• (a) a plasma chamber having axially spaced inlet and outlet ends;
• (b) a high temperature plasma positioned adjacent the inlet end of the plasma chamber;
• (c) at least one precursor inlet for introducing a precursor to the plasma chamber where the precursor is heated by the plasma to produce a gaseous product stream flowing toward the outlet end of the plasma chamber;
• and
• (d) a converging member located adjacent the outlet end of the plasma chamber through which the gaseous product stream flows, wherein a substantially uniform material flow pattern is maintained in the plasma chamber and the converging member during operation of the apparatus.

A method of making ultrafine particles comprising:

• introducing a precursor material into a plasma chamber;
• heating the precursor material in the plasma chamber with a plasma to produce a gaseous product stream flowing toward an outlet end of the plasma chamber;
• and
• passing the gaseous product stream through a converging member located adjacent the outlet end of the plasma chamber, wherein a substantially constant pressure and a substantially uniform material flow pattern are maintained in the plasma chamber and converging member as the gaseous product stream flows through the plasma chamber and converging member.