Why Negative Hydrogen/Deuterium Ion Generators?

Auto-Search gives me some hints.

I did a Google for "Hydrogen Ion Generator" and got a load of hits about "Negative Hydrogen Ion Generators". They almost seem to be 'fusion specific'. Are they used because the required end result is a neutral beam of Hydrogen/Deuterium for injection into the fusion chamber and the negative ions can be accelerated with the extra electron being easily stripped off before injection?

 

[Astronuc]

Negative ion sources are also used with accelerators.

One author puts it: "The electron captured in the negative ion has a very low binding energy called affinity of E_a = 0.75 eV. Ion can easily lose the electron and become neutral, and this is a reason why a high neutralisation efficiency can be achieved with negative ions."
Ref: http://mafija.fmf.uni-lj.si/seminar/files/2004_2005/NBI1.pdf

Some discussion in the following papers:
FermiLab - Negative Hydrogen Ion Sources for Accelerators
IAEA - Ion Sources

One can also search on "neutral beam injection".