Saddle-field gun

A FAB ion source basically is an El ion source (Chap. 5.2.1) modified to give free access to the fast atom beam. The electron-emitting filament and the ion source heaters are switched off during FAB operation (Fig. 10.1). The FAB gas is introduced via a needle valve into the lower part of the FAB gun mounted above the ion source. From there, it effuses into the ionization chamber of the FAB gun and into the ion source housing. The saddle field gun [27] is the most common type of... 

Alexander, A.J. Hogg, A.M. Characterization of a Saddle-Field Discharge Gun for FABMS Using Different Discharge Vapors. Int. J. Mass Spectrom. Ion Proc. 1986,69, 297-311. 

Fast Aloin Bombariiment (FAB-MS). This was applied to Study the lactonization of HIL to ADF FAB-MS was performed on a Finnigan MAT 8430 double focusing mass spectrometer. FAB ionisation was carried out with a saddle-field atom gun (Ion Tech. Teddington, UK) which was operated at 2 raA and 7-8 kV with xenon. Glycerol was used as matrix. The positive ions at m/z 130 (protonated molecular ion of ADF) and 148 (protonated molecular ion of HIL) were recorded. 

Here the source of primary beam is xenon atoms, which because of higher mass and momentum provides better sensitivity than that of the beam of argon atoms used in the original discovery. The xenon atoms are first ionized in the FAB gun by collisions with electrons that are moving in a saddle-field configuration. 

Boggess, B. Cook, K.D. Detenmjiation of Flux From a Saddle Field Fast-Atom Bombardment Gun. J. Am. Soc. Mass Spectrom. 1994,5,100-105. 

The saddle field ion gun was first used for traditional ion thinning of materials, such as metals [460]. The ion beam sputtering (IBS) method uses a fine, collimated, and water cooled ion source that sputters metal from a target onto the specimen surface. Argon is directed into the ion gun, and the specimen is neither heated nor bombarded by the plasma as is generally the case in ordinary sputter coating. The device is... 

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