ERRORS AND LIMITS IN THE DETERMINATION OF PLASMA ELECTRON-DENSITY BY MEASURING THE ABSOLUTE VALUES OF THE EMITTED CONTINUUM RADIATION INTENSITY

The reliable determination of a plasma electron density structure requ ires a good knowledge of the errors affecting the employed technique. We have used a technique based on the measurement of the absolute ligh t intensity emitted by travelling plasma structures in plasma focus de vices, but it can be easily modified to other geometries and even to s tationary plasma structures with time-varying plasma densities. The pu rpose of this work is to discuss in some detail the errors and limits of this technique. Three separate errors are shown: the minimum size o f the density structure that can be resolved, an overall error in the measurements themselves, and an uncertainty in the shape of the densit y profile.