Thermal Helium Beam Spectroscopy at the DIII-D Helicon Antenna*

A thermal helium beam diagnostic (He-Beam) has been commissioned at the DIII-D tokamak. The diagnostic aims to measure the radial profiles of plasma density and temperature in the scrape-off layer surrounding the helicon antenna. These measurements are essential for evaluating plasma heating methods and for the general characterization of DIII-D boundary plasmas. The diagnostic is composed of two spectrometers with eighteen lines of sight each. A piezoelectric gas control system allows for precise puffs of helium gas above and below the helicon antenna, and using a collisional radiative model (CRM), the radial density and temperature profiles can be inferred via a line ratio technique. This method compares the intensity of lines at 667.8 nm, 706.5 nm, and 728.1 nm, which have shown good agreement with Thomson and Langmuir data in previous implementations at both Wendelstein-7X and ASDEX Upgrade.  Measurable signals for this diagnostic range from 1x10¹⁸ m^-3 < n_e < 5x10¹⁹ m^-3 for density and 15eV < T_e < 400 eV for temperature when making use of a new, time-dependent CRM. This contribution presents the details of the diagnostic setup, and first results from shots with and without helicon antenna operation. Along with first results, future goals will be presented and discussed.