Gas cell for the optical analysis of gases

摘要

A measuring cell for a gas analysis spectrometer has an inner chamber for a sample gas to be analyzed and an inlet and an outlet which are connected thereto. A traversing optical path for a measuring beam is formed in the inner chamber. The measuring cell is tubular, the inlet and the outlet are arranged at opposite ends, and the inner chamber of the measuring cell has a cross-sectional shape that is monotonic over the length of the tube and which has an oval-shape at the start, which disappears toward the end. That special shape results in fast gas exchange and thus high dynamics, even with larger measuring cells, which have high sensitivity due to the long optical paths thereof. Two characteristics which until now appeared to be conflicting are thereby combined.

主权项

1. A flow-through measuring cell for a gas analysis spectrometer, the measuring cell comprising:
a casing having a tubular inner chamber for a sample gas to be analyzed, said casing having a first end, a second end and a center axis; an inlet mounted on said casing proximate said first end, said inlet having a tangential component; an outlet mounted on said casing proximate said second end, wherein the sample gas passes from said inlet, through said tubular inner chamber and into said outlet, said casing having a substantially oval, non-circular cross-sectional shape proximate said inlet, which decreases monotonically along a length thereof and substantially vanishes proximate said outlet; a first concave mirror having an upper reflective surface, said first concave mirror being disposed between said inlet and said first end of said casing, said first concave mirror having an elongated shape which seats within and is matched to said oval cross-sectional shape of said casing, wherein the sample gas passes from said inlet directly into said casing at an axial location along said casing which is above said upper reflective surface of said first concave mirror; and a second concave mirror disposed between said outlet and said second end of said casing, said first and said second mirrors thereby inducing a multiply reflected, fanned out optical path for a measuring beam in said casing, wherein said tangential component of said inlet and said cross-sectional shape of said casing are disposed, structured and dimensioned to generate a defined vortex of sample gas flow within said casing, said vortex gradually turning into an increasingly circular vortex with a slowly decreasing peripheral speed as the sample gas passes from said inlet to said outlet.