VUV emission spectroscopy diagnostics of a 14 GHz ECR negative hydrogen ion source

Abstract

Vacuum Ultra Violet(VUV) emission from a 4cm diameter 2cm long compact ion source excited by 14GHzmicrowave has been investigated. Intensity ratio of band spectrum emission near Ly-α to Ly-α line spectrum is determined from themeasured spectrum. which shows preferential excitation ofmolecules near the entrance ofmicrowave input power. The ratio does not depend strongly upon pressure nor the inputmicrowave power when the intensity is integrated over the volume of the plasma. The spatial distribution of the spectrum intensity ratio exhibits concentrations nearmicrowave inlet and the opposite side where themicrowavematching structure is located. The ratio at these peripheral regions is about two times as high as that of the central region. The ratio increased in proportion to the ion source pressure up to about 3.0Pa, indicating efficient production of high energy electrons by ECR up to this pressure.