Influence of Ambient-Air Nitrogen on the Argon Plasma Generated by a TIAGO Torch Open to Atmosphere

Microwave-torch plasmas sustained in easy-to-ionize gases such as argon are strongly affected by the presence of nitrogen when emerging into ambient air. Examination of pictures of their flame as a function of distance from the torch tip provides information to the setting of operating conditions (gas flow and microwave power) such as to minimize contamination of the discharge by nitrogen.