Preliminary Evaluation of a Modified Mueller-Hortig Geometry Negative Ion Source Using a Negative Ion Source Test Facility

A negative sputter-type ion source of the Mueller-Hortig geometry is described which utilizes a positive surface ionization source. Among the ion beams which have been produced are: A1-0.2 μA; A10--3 μA; Au--6 μA; C--25 μA; C2--20 μA; Cl--100 μA; Cu--0.5 μA; CuO--0.8 μA; F--40 μA; I--26 μA; 0--30 μA; Pt--3 μA; S--44 μA; TaO2--2 μA. The yields of Cl-, F-, O-, and S- produced from gaseous or high vapor pressure compounds are observed to be sensitively dependent on the metallic surface from which they are generated - indicating an intermediate surface chemical effect. While the source produces very intense beams of the halogens, sulfur, and oxygen and relatively intense beams of the metallic oxides, there appears to be a need for additional surface cesium to ensure maximum negative ion yields from many of the elemental materials.