Toroidal plasma abatement apparatus and method

Abstract

An apparatus for abatement of gases is provided. The apparatus includes a toroidal plasma chamber having a plurality of inlets and an outlet, and at least one chamber wall. One or more magnetic cores are disposed relative to the toroidal plasma chamber. The plasma chamber confines a toroidal plasma. A second gas inlet is positioned on the toroidal plasma chamber between a first gas inlet and the gas outlet at a distance d from the gas outlet, such that a toroidal plasma channel volume between the first gas inlet and the second gas inlet in the is substantially filled by the inert gas, the distance d based on a desired residence time of the gas to be abated.

What is claimed is: 
     
         1 . A method for abating process gas within a plasma source, the method comprising:
 flowing via a first gas inlet, a first gas for ignition into a plasma into a toroidal plasma chamber having a primary winding coupled to the plasma chamber and a plurality of magnetic cores oriented such that the plasma chamber passes through each of the plurality of magnetic cores;   generating a toroidal plasma in the toroidal plasma chamber along a plane extending through the toroidal plasma chamber;   positioning a second gas inlet between the first gas inlet and a gas outlet at a distance d from the gas outlet along the plane, the distance d based on a desired residence time of a gas to be abated; and   flowing via the second gas inlet, the gas to be abated into the toroidal plasma chamber such that the gas to be abated reacts with the toroidal plasma.   
     
     
         2 . The method of  claim 1 , further comprising adjusting the position of the second gas inlet to control the desired residence time of the gas to be abated. 
     
     
         3 . The method of  claim 1 , further comprising adjusting a flow rate of the first gas flowing into the plasma chamber such that a first toroidal plasma channel volume between the first gas inlet and the second gas inlet in the toroidal plasma chamber is substantially filled by the first gas and a second toroidal plasma channel volume between the second gas inlet and the gas outlet is substantially filed with the gas to be abated. 
     
     
         4 . The method of  claim 1 , further comprising providing a reactant gas to mix with the gas to be abated before flowing into the plasma chamber via the second gas inlet. 
     
     
         5 . The method of  claim 1 , further comprising providing a water vapor to mix with the gas to be abated before flowing into the plasma chamber via the second gas inlet. 
     
     
         6 . The method of  claim 1 , further comprising monitoring an emission from the plasma chamber via an optical and/or an infrared sensor and adjusting a flow rate of the reactant gas in response to the emission from the plasma chamber such that a concentration of the reactant gas is at a desired level to react with the gas to be abated. 
     
     
         7 . The method of  claim 1  further comprising coupling the gas outlet to a subsequent treatment device. 
     
     
         8 . The method of  claim 1  wherein generating the toroidal plasma further comprises:
 coupling an RF power supply to the primary winding; and 
 delivering power to the toroidal plasma. 
 
     
     
         9 . The method of  claim 3 , further comprising coupling an RF power supply to the primary winding. 
     
     
         10 . The method of  claim 9  further comprising delivering a constant plasma current through the first toroidal plasma channel volume and the second toroidal plasma channel volume. 
     
     
         11 . The method of  claim 1  wherein positioning the second gas inlet further comprises orienting the second gas inlet at an acute angle to the plane. 
     
     
         12 . The method of  claim 1  wherein positioning the second gas inlet further comprises positioning the second gas inlet between the first gas inlet and the gas outlet at a distance approximately 2 to 5 inches from the gas outlet along the plane. 
     
     
         13 . The method of  claim 1  further comprising selecting the second gas inlet from a series of selectable gas inlet ports positioned along the toroidal plasma chamber.