Vibrational excitation molecule maximum production in helicon hydrogen negative ion sources at 0.3 Pa for negative neutral beam injectors

The effects of the main parameters of the helicon plasma sources on the volume process of the negative ion production mechanism are investigated. Using COMSOL Multi-Physics software, a helicon plasma source as a source driver of a negative ion source is modelled in three dimensions. In this work, it is considered that the helicon plasma source employs a Nagoya-type antenna at an operational frequency of 13.56 MHz. The influences of the static magnetic field variation, applied radio frequency power and injected gas pressure on electron/plasma density, electron temperature and vibrationally excited molecular density are studied. Variations of the static magnetic field in a range of 0.01–0.08 T, Radio Frequency (RF) power in a range of 800–6000 W and gas pressure range of 0.3–1.5 Pa indicate that the maximum electron (plasma) density is increased in all three cases; nevertheless, the electron temperature and maximum density of the vibrationally excited molecules is increased just by RF power increment. For the pressure of 0.3 Pa, it is found that using a proper coil configuration, the electron density and the vibrationally excited molecular density will be increased without the magnetic field (applied DC power) increment and RF power increment.