R&D Status of Neutral Beam Assisted Diagnostics on the Hanbit Mirror Device

Two types of neutral beam sources have been developed in order to measure plasma parameters on the Hanbit mirror device. The first source is a diagnostic neutral beam (DNB) which consists of a hydrogen neutral beam with a beam energy of 30 keV and a total beam current of ca. 1 A. The ion temperature profile can be determined by measuring directly the broadening of the H_α line emitted from hydrogen neutrals produced through the charge exchange recombination reaction with the DNB in the plasma. A fibre optic array detector, which works as an ideal notching filter, was developed to filter out the intense H_α line emitted from the cold hydrogen atoms in the plasma edge. The second source is a hyperthermal neutral beam (HNB) which consists of neutral particles with an energy of 1-100 eV. The HNB can be used to measure electron temperature and density profiles in the region between the core and the outer edge. This region cannot be covered either by Thomson scattering or by electrostatic probes. The feasibility of obtaining profiles of electron density and temperature by means of a helium HNB with a collisonal radiative equilibrium code has been performed.