Numerical study of the H⁰ atomic density and the balmer line intensity profiles in a hydrogen negative ion source with the effect of non-equilibrium electron energy distribution function

Spatial profiles of the atomic (H⁰) density and the resultant H_α line intensity are investigated in a large negative ion source (the Japan Atomic Energy Agency (JAEA) 10 A negative ion source). The H⁰ density analysis has been done in the present study with the effects of production, transport, and ionization processes by taking into account the non-Maxwellian component of electron energy distribution function (EEDF). The H⁰ density profile shows a non-uniform spatial profile due to the local enhancement of the H⁰ production rate even with the flattening effects by the ionization and the transport processes. The H_α line intensity observed from the viewing ports in the spectrometry is compared with the line intensity in the calculation to validate the numerical results. The both results show a good agreement in the spatial profile. It has been shown that the non-Maxwellian component of the EEDF plays an important role to determine the profile of the H_α line intensity in the plasma production region. (author)