Surface ionization negative ion source

Abstract

A negative ion source that utilizes a porous lanthanum hexaboride surface to generate iodine ions is described. Iodine vapor supplied to the back of the lanthanum hexaboride ionizer from a reservoir percolates through to the front surface where the iodine is evaporated as ions. The peak ion current obtained—2.1 mA at an ion energy of 0.3 keV—leads to a density n≃1010 cm−3.

Fundamentals of accelerator mass spectrometry

“…An alternative procedure involving charge exchange at kiloelectronvolt energies in metal vapours (Heinemeier & Hvelplund 1978) has proved to be useful. In this case, positive ions are first generated by a sputter-ion source such as the I-source pioneered by Rachidi et al (1976). These ion sources produce many microamperes of p ions from atoms with low electron-binding energy, such as aluminium, and these can readily be accelerated to many kiloelectronvolts (Aardsma 1983).…”

“…Positive-ion sources for injection into accelerators other than tandem accelerators can be of a variety of types although low-memory, low-energy spread negative halogen sputter-ion sources are ideal (Rachidi et al 1976;Aardsma 1983).…”

Mass spectrometry with accelerators

“…Also sputtering by Kr þ or Xe þ , for example, then removes the chemical effects of Cs implantation or may change them in possibly useful ways. Sputtering with I À ions (Rachidi et al, 1974;Aardsma, 1984) provides large beams of ions such as Al þ from insulators. These cations have to be converted to anions for tandem acceleration in, for example, lithium vapor and that has to be done at the price of beam degradation by multiple scattering and energy spread.…”