Journal of Radio Electronics. eISSN 1684-1719. 2024. ¹12

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DOI: https://doi.org/10.30898/1684-1719.2024.12.3  

 

 

 

APPROACH TO MEASURING A SUBNANOAMPERE
FIELD-EMISSION CURRENT

 

Yu.A. Zemskov, Yu.I. Mamontov, P.S. Mikhailov,
I.L. Muzyukin, I.V. Uimanov

 

Institute of Electrophysics of the Ural Branch of the Russian Academy of Sciences
620016, Russia, Yekaterinburg, Amundsena Str., 106

 

The paper was received November 19, 2024.

 

Abstract. The paper describes a designed and tested approach to the field emission current measurement within a wide current range of 7-8 orders of magnitude. An experimental setup employed was based on a high vacuum chamber with a residual gas pressure of not worse than 10‑6 Pa. A field emissive cathode was a thin pure copper needle with a hemispherical tip. A cathode diameter was ~70 µm, a tip hemisphere radius was ~35 µm, a cathode length was ~15 mm. An anode was a flat phosphorous screen. The emission current was measured within the cathode circuit. Two different approaches were employed to measure the current. Within the current range of 1 nA – 10 µA, we used an ordinary 1‑MOhm current shunt. To measure the emission current below 1 nA, we employed the charge collection approach when a current-measuring capacitor was charged by the field emission current for some particular collection period. Then, the capacitor was connected to an oscilloscope input. A signal of the capacitor discharge through the oscilloscope input impedance was registered. The signal amplitude gave information on the emission current averaged over the collection period. Employing this approach, we managed to measure the emission current of ~0.2 pA. In addition, the limitations of the approach were investigated.

Key words: field electron emission, emission current, current measurement, capacitors.

Financing: The work was carried out under the state task for IEP UB RAS, task theme No. 122011200367-7.

Corresponding author: Yuriy Igorevich Mamontov, mamontov@iep.uran.ru

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For citation:

Zemskov Yu.A., Mamontov Yu.I., Mikhailov P.S., Muzyukin I.L., Uimanov I.V. Approach to measuring a subnanoampere field-emission current. // Journal of Radio Electronics. – 2024. – ¹. 12. https://doi.org/10.30898/1684-1719.2024.12.3 (In Russian)