Cavity enhanced plasma self-absorption spectroscopy

We introduce cavity enhanced plasma self-absorption spectroscopy (CEpSAS), a sensitive spectroscopic diagnostic tool that is used here for plasma analysis, but can also be used for any light emitting sample. It works without an additional external light source. In CEpSAS, plasma is located in an optically stable cavity consisting of two high reflectivity mirrors, and here it acts both as light source and absorbing medium. We present proof of principle results to illustrate the performance of this technique that literally combines "sense and simplicity." Quantitative absorption experiments are described on a supersonically expanding hydrocarbon plasma.