The construction of a gas ion source

Hydrogen or rare-gas ions can be produced in high electric fields around very fine tips in the so-called gas field-ionization sources. For the purpose of a powerful ion source on these tips an elevation, the so-called super-tip, must be grown. The aim of this thesis was, to construct such a gas field-ionization source and study in its essential parameters ans, as far already possible, test on its suitability as ion sources. After the construction of the source systematic studies on the field ion current on tungsten tips in dependence on the pressure, the field strength, the tip temperature, the tip radius r, the kind of gas, and the gas temperature T were performed. The field ion current increases linear with the pressure, at least with T-1 and with r2.5. By optimization of these parameters currents of several 100 nA are possible from an emitter without super-tip. Because of the requirement of as low as possible tip and gas temperatures especially H2, and Neon are predestinated for such a source. The results of this thesis permit the application of a gas field-ionization source structurated with super-tips as a ion source. To a liquid-metal source it is thereby with its possible directed-beam value of 109 A/cm-2 sr, an energy-sharpness of 1 eV, and a virtual source size of about 1 nm essentially superior. (orig./HSI)