A computer-controlled data acquisition and analysis system for use in the characterization of plasma atomic emission sources

The characterization of new spectroscopic plasma sources for use in atomic emission spectroscopy often presents the need for information about the spatial emission characteristics of the source. In addition, information about the variation of the emission over time is often beneficial. It is also useful to be able to graphically see, in real-time, the effects of varying a particular experimental parameter. This paper describes a flexible data acquisition system in which an echelle spectrometer is interfaced to an IBM-PC compatible microcomputer. The FORTH-based ASYST software, which proves real-time display of acquired data, allows any point in the emission source to be imaged on the entrance slit of the spectrometer by using the cursor keys of the PC and a computer-controlled mirror. The different acquisition modes of the system are illustrated with examples of two-dimensional spatial profiles of the plasma and monitoring of plasma stability over time. In addition, an illustration of the optimization of the echelle's aperture plate and photomultiplier tube positions in the focal plane is presented.