Microwave plasma torch operating at a low pressure for material processing

Abstract

Most operations involving the use of a microwave plasma torch are carried out at atmospheric pressure as an open system. A microwave plasma torch operated in a closed and isolated environment may provide an opportunity for the mass production of chemically active radicals for various chemical and biological processes. This study presents a microwave plasma torch operating at a low pressure in an isolated chamber. A microwave torch operating at a low pressure may be economical in terms of capital costs, maintenance costs, and operational costs compared to other plasma devices used in material processing operations. The properties of the torch plasma at a low pressure were investigated. It is found that the plasma profile at a low pressure is asymmetric with higher density on the incoming side of the microwaves. This behavior of the torch inhibits high-power operation of the microwave plasma torch at a low pressure. However, the asymmetry of the plasma profile disappears under a high gas flow rate. It was also found that a microwave plasma torch used at a low pressure can efficiently produce an abundance of chemical radicals.