Non-Linear Corrections to Spectroscopic Temperature Measurements in Turbulent Arc Plasmas

摘要

A detailed study was made of the statistical properties of short time local temperature fluctuations in a turbulent arc plasma jet with temperatures ranging from 4000-7000K. The results of the study are given in the form of autocorrelation functions of temperature fluctuations at various locations in the plasma jet. Instantaneous temperatures were measured spectroscopically using violet CN band spectra and fluctuations could be determined on time scales as short as 1-2 microseconds. One objective of the study was to develop a relatively simple means of correcting the apparent temperature as measured by a slow integrating detector such as the photographic plate used in conventional spectroscopy to obtain the true average temperature obtained from time-resolved spectroscopic methods. A tentative method is proposed for evaluating the difference between apparent and true average temperatures in a turbulent plasma by an empirical relation between brightness fluctuations and temperature fluctuations that allows the latter to be inferred from measurements of the former which can be carried out with very simple equipment. (Author)