H− density profile and response to applied bias and extraction voltages in H− source

Evaluation of negative ion distribution changes by image processing diagnostic

“…We confirm the same property of the distribution between ΔH α and ΔH α /H α near PG surface as shown in Figure 6(a) and Figure 7(a). Therefore, H α reduction is caused by the reduction in the excited hydrogen (n = 3) population, which in turn is caused by the decrease in H -ions, which reduction property is the same as the H -ion density measured by CRDS [16].…”

“…However, this condition is not useful because a negative ion current also decreases caused by poor H -reduction in the extraction region. The same poor H -reduction and decreased H -densities have been observed by CRDS [16]. Since the ΔH α /H α also decreases in this bias condition, we consider that the actual number of negative ions release from the PG surface, which is close to relate the negative ion density, is reduced when the positive PG potential is larger than the plasma potential.…”

Research progress on ionic plasmas generated in an intense hydrogen negative ion source

“…4(a), and this phenomenon is influenced by the bias voltage, which is applied to the PG with respect to the arc chamber [9]. Figure 4(b) shows the H -density normalized by the arc power as a function of the bias voltage with and without the beam extraction.…”

Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

“…This approach is pursued via (pulsed) cavity ring-down spectroscopy (CRDS), where the decay time of a laser pulse in an optical cavity is measured. This high-sensitive method of absorption spectroscopy was introduced by O'Keefe and Deacon [3] and since then frequently applied to obtain reliable absolute, but line-of-sight averaged negative hydrogen ion densities [4,5,6,7]. In contrast to laser photodetachment, CRDS is a non-invasive diagnostic method, but not capable of specifically space-resolved investigations of the negative ion density.…”