Publication: Electrical properties of He-induced W "fuzz" within the pre-breakdown and breakdown regimes
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2020
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© 2021 IEEEThe investigation of the He-induced W "fuzz" electrical properties was carried out. For the research, an automated experimental setup was designed. The setup was based on a vacuum chamber operated under high vacuum condition (~10-7 Pa). The vacuum diode under investigation comprised of a flat W “fuzz” cathode with an area of about 1 cm2 and a 2 mm radius cylindrical copper anode rounded with a 2 mm radius hemisphere. The cathode-anode distance was ~100 μm. The voltage applied was up to 10 kV. An HV power supply was controlled employing the DAC/ADC module “LCardTM E20-10”. This module registered automatically currents and voltages of interest also. As the result, the data on the dielectric strength of the diode with the W “fuzz” cathode were obtained. The effect of the cathode conditioning was demonstrated. An increase in the breakdown electric field strength from about 4·105 V/cm for the very first breakdown up to 9·105 V/cm for the 20th breakdown was registered. In addition, the emissive characteristics of the W "fuzz" cathode were studied in accordance with the Fowler-Nordheim theory. The estimated value of the electric field enhancement factor ȕ near the cathode surface was found to be ~60 before the breakdown and ~80 after the breakdown. The obtained ȕ values were somewhat smaller than the ones obtained by other research groups for the nanostructured W cathodes. This fact should be investigated additionally.
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Electrical properties of He-induced W "fuzz" within the pre-breakdown and breakdown regimes / Mamontov, Y.I. [et al.] // Proceedings - International Symposium on Discharges and Electrical Insulation in Vacuum, ISDEIV. - 2020. - 2021-September. - P. 69-72. - 10.1109/ISDEIV46977.2021.9587227