are produced by a hot-wire ion source in a atmosphere of argon gas, then Ar+ are accelerated by electric field into second chamber containing with neutral gas atoms at bout 10-5 tor. Collision between Ar+ and thermal atoms to become fast atoms (20-30 KeV), and ions removed by a charged deflector plate. The fast atom go directly into solid sample to produce sample ions.
Solid sample are dissolved in non-volatile liquid matrix such as glycerol or carbowax