Optical Emission Spectroscopy Diagnostic for an ECR Dissociator

Project 8 is a direct neutrino mass experiment that uses tritium beta decay to measure the absolute neutrino mass scale. To extend sensitivity in future phases, the collaboration will transition from molecular to atomic tritium. An electron cyclotron resonance (ECR) source is being constructed to dissociate molecular tritium using an RF source to induce a plasma. We estimate the dissociation fraction in the ECR source by using optical emission spectroscopy to analyze the relative intensities of the Balmer lines and molecular Fulcher band. A deuterium discharge tube was used to characterize the spectrometer prior to operation of the ECR source. Spectrometer performance is optimized by averaging short integration times to preserve weak emission features without saturating strong peaks. To improve diagnostic accuracy, we investigate whether saturation of the Balmer-alpha line affects the measurement of nearby unsaturated spectral features. This work presents the current status of spectrometer characterization and outlines our approach for measuring dissociation in the ECR source in preparation for atomic tritium use in Project 8.