Trace hazardous metals detection with ant atmospheric microwave-generated plasma

Summary form only given. A 1.5 kW atmospheric microwave plasma at 2.45 GHz is being developed as an excitation source for real-time detection of hazardous metals in smokestack exhaust. There is currently an important need for metal continuous emissions monitors (CEMs) to meet current and future clean air regulations. A number of plasma generation methods for metal atomic emission spectroscopy are being tested for this application including inductively coupled plasmas (ICPs), laser sparks, DC electrode sparks, and microwave discharges. The microwave plasma has a significant advantage to continuously operate robustly in large volumes of fast flowing (/spl ges/14 1/minute) air or undiluted stack exhaust. Experimental measurements will be presented of the performance of this microwave plasma with Hg, Cd and As as a function of oxygen additive. An attempt will be made to explain the behavior in terms of the possible UV absorption and atomic excitation mechanisms in the plasma.