A practical method for plasma diagnosis with Balmer series hydrogen lines

Abstract

Hydrogen Balmer series lines have been widely used to determine characteristic plasma parameters such as electron density. These parameters are related to internal processes occurring in plasma (Stark effect, Doppler effect, …) which give rise to line shapes whose convolution reproduces the total atomic emission line. This procedure provides an estimation of plasma parameters but it requires a large amount of computing time in the data treatment for the convolution operations. In this paper we develop an alternative and practical method for diagnosis of the hydrogen atomic lines based on the fact that while most of these processes give rise to line shapes described in terms of simple analytical functions (Lorentzian and Gaussian functions), the Stark effect must be approximated by a sum of Lorentzian functions. With this proposed method a significant decrease in computational cost is achieved what allows minimizing the impact of the process on time and resources. Also, this method has been verified experimentally in an electron density range from 1·1014 to 1·1016 cm−3.