A new approach for explanation of specimen rupture under high electric field.

Failure of needle-shaped specimens under the action of high electric fields is one of the most serious problems in many field-ionization devices and methods. It was shown that the length of what was removed during discharge part of specimens in most of the cases was several orders greater than that of an initial radius of the specimen apex. Experimental results obtained in this work indicate that electrical breakdown in field-ion microscopes is initiated by the impact of nanoparticles detached from a point anode in a high electric field.

Investigation of rf power absorption in the plasma of helicon ion source.

The simulations of the spatial distribution of rf power absorbed in a helicon ion source reveal a correlation between the depth of penetration of rf power into the plasma and the tilt angle of lines of force of the outer magnetic field. The deeper field penetration and greater power absorption were observed at large tilt angles of the field line to the plasma surface. The evaluations as to the possibility of excitation of helicon waves in compact rf ion sources were performed.

Investigation of helicon ion source extraction systems.

Various versions of an extraction system for a helicon ion source have been investigated in high plasma density (>10(12) cm(-3)) modes. The measurements of the plasma density were carried out with a microwave interferometer. Experiments were performed with hydrogen and helium gases.