Articles you may be interested inA hollow cathode ion source for production of primary ions for the BNL electron beam ion sourcea) Rev. Sci. Instrum. 85, 02C107 (2014); 10.1063/1.4852235 Performance of an inverted ion source Rev. Sci. Instrum. 84, 023506 (2013); 10.1063/1.4793377 Nanostructure operations by means of the liquid metal ion sourcesa) Rev. Sci. Instrum. 83, 02B906 (2012); 10.1063/1.3670340 Ion optics of RHIC electron beam ion sourcea) Rev. Sci. Instrum. 83, 02A504 (2012); 10.1063/1.3666915 Characterization of atomic-size metal ion sources
Factors affecting the current-voltage characteristics of liquid metal ion sources are reviewed. The results demonstrate that ion emission is not controlled by space-charge effects but rather is determined by liquid flow limitations along the needle emitter. A hydrodynamic model is presented which predicts the experimental I-V characteristics. The model suggests that a reduction in the energy spread (Boersch Effect) of the emitted ions may be achieved by increasing the needle flow impedance.
Liquid indium ions sources were operated in a transmission electron microscope. The formation of a Taylor cone was directly observed during source operation. In addition, dynamic instabilities were observed on the needle shank behind the Taylor cone with the formation of liquid droplets which grew in size and left the shank. Droplets on the shank were also found in SEM observations of rapidly frozen liquid gold ion sources. The surface of silicon targets on which the ion current from a gallium ion source was allowed to impinge was studied by Rutherford backscattering spectrometry. The amount of material emitted from the ion source was measured as a function of the angle of emission and the ion current. A comparison of these emitted mass distributions with the corresponding current distributions indicated that the average mass to charge ratio of the beam decreased with angle of emission. In addition, the ratio of the amount of material to the total charge leaving the source was found to increase monotonically with the ion current with a sharp increase occurring for ion currents greater than approximately 10 μA.
We have studied the dependence of the energy spread of the ions from Au liquid metal ion sources (LMIS) on the hydrodynamic flow conditions of the liquid imposed by the surface smoothness or roughness of the source tip. We have also studied the dependence of the energy spread on the source current and angle of emission. The changes in energy spread with source roughness expected on the bas is of current models and theory for the range of sources we have examined is relatively small. Nevertheless our results cast doubt on the existing theory for hemispherical electric field geometries. The source current dependence of energy spread is well represented by a power law ƊE~Iα where α is between 0.32 and 0.39, much less than the anticipated 0.66 which has been reported for Ga sources and expected from the simplest interpretation of longitudinal space-charge effects. The dependence of energy spread on eagle of emission for Au sources shows a remarkable anti-correlation with the angular dependence of current density. All of these measurements suggest that the picture of a smooth and stable liquid tip from which field evaporation produces stable atomic ion beams is much too simple
Corona discharges caused by water droplets on the surface of polymeric insulators can affect the long-term reliability of the component by lowering the surface hydrophobicity encouraging surface discharges. It is well-known that droplet-initiated discharges behave differently under AC and DC field stress affecting the hydrophobicity of polymeric outdoor insulation materials. The presented investigations study the effect of hybrid field stress on partial discharges at singular water droplets. The behavior differs depending on the direction of the electric field as also known for uniform AC or DC fields. Tangential oriented field stress is more critical to aging phenomena due to a significantly lower pd inception level. By high speed analysis of the droplet deformation the oscillation frequency is linked to the acting electrostatic forces depending on the AC and DC component of the excitatory electric field. Thus, the mechanical oscillation model is extended for hybrid field stress.
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