Mikhailovskij, I.M. ; Wanderka, N. ; Storizhko, V.E. ; Ksenofontov, V.A. ; Mazilova, T.I.: A new approach for explanation of specimen rupture under high electric field. Ultramicroscopy 109 (2009), p. 480-485
10.1016/j.ultramic.2008.12.003
Abstract:
Failure of needle-shaped specimens under the action of high eJectric fields is one of the most serious problems in rnany 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 eleetric field. A new approach for explanation of an observed specimen failure in a high eleetric field was proposed, where the formation and expansion of the cathode plasma play the key roje in the mechanical rupture and melting of field-ion tips. The expanding plasma behaves as a dynamic capacitor plate characterized bya high velocity and increasing field strength at the specimen tip. The field rise rate at a constant voltage in a dynamic plasma-to-tip capacitor is of the order of > 1020 V/m/s. The present experimental data along with the ecton model of the vacuum breakdown allow the results to be discussed as a mechanical sampie failure under the action of the superhigh positive field pulse induCl;d by the cathode plasma expansion.