Volume Production Of Hydrogen Negative Ions

The causes of observed saturation of hydrogen negative ion current at high power operation of tandem volume sources are investigated using a zero-dimensional time-dependent model, which assumes that dissociative electron attachment to highly vibrationally excited molecules is the main formation mechanism of hydrogen negative ions. It was found that the reason for saturation was the reduction of the density of molecular hydrogen, as a result of dissociation. The mean free path of the vibrationally excited molecules for various destruction processes will be discussed in relation with the source high power operation.