First Beam Characterization by Means of Emission Spectroscopy in the NIO1 Experiment

TL;DR

This paper presents the first use of emission spectroscopy, specifically Beam Emission Spectroscopy (BES), to characterize the beam in the NIO1 experiment, providing insights into beam divergence, uniformity, and ion neutralization.

Contribution

It introduces a novel application of BES diagnostics for beam characterization in the NIO1 ion source experiment, including setup, analysis algorithms, and initial measurement results.

Findings

Successful measurement of beam divergence and uniformity.

Correlation between BES measurements and operational parameters.

First demonstration of emission spectroscopy for beam analysis in NIO1.

Abstract

The NIO1 experiment hosts a flexible RF H- ion source, developed by INFN-LNL and Consorzio RFX to improve the present concepts for the production and acceleration of negative ions. The source is also used to benchmark the instrumentation dedicated to the ITER neutral beam test facility. Many diagnostics are installed in NIO1 to characterize the source and the extracted negative ion beam. Among them, Beam Emission Spectroscopy (BES) has been used in NIO1 to measure the divergence and the uniformity of the beam, together with the fraction of beam ions which was neutralized inside the acceleration system. The diagnostic method is based on the analysis of the Doppler shifted $H_\alpha$ photons emitted by the fast beam particles and collected along a line of sight. The article presents the experimental setup and the analysis algorithms of the BES diagnostic, together with a discussion of the first measurements and of their correlation with the operational parameters.