Structural and functional synthesis of the continuous wave NQR temperature sensor with increased conversion linearity

A Samila; I Safronov; O Hotra

doi:10.1016/j.ssnmr.2020.101700

Structural and functional synthesis of the continuous wave NQR temperature sensor with increased conversion linearity

Solid State Nucl Magn Reson. 2020 Dec:110:101700. doi: 10.1016/j.ssnmr.2020.101700. Epub 2020 Nov 12.

Authors

A Samila¹, I Safronov², O Hotra³

Affiliations

¹ Department of Radio Engineering and Information Security, Yuriy Fedkovych Chernivtsi National University, Kotsjubynskyi 2, 58012, Chernivtsi, Ukraine. Electronic address: a.samila@chnu.edu.ua.
² Department of Radio Engineering and Information Security, Yuriy Fedkovych Chernivtsi National University, Kotsjubynskyi 2, 58012, Chernivtsi, Ukraine.
³ Institute of Electronics and Information Technology, Lublin University of Technology, Nadbytrzycka 38A, 20618, Lublin, Poland.

PMID: 33212304
DOI: 10.1016/j.ssnmr.2020.101700

Abstract

The paper describes development of the detailed structure and circuit diagrams of the continuous wave NQR temperature sensor with increased conversion linearity. It is experimentally established that at amplitude modulation of 40% and change of input voltage in the range of 20-1000 mV, the circuit of a symmetric marginal oscillator with a linear active demodulator provides better linearity of transfer characteristic than the circuits of asymmetric marginal oscillators with JFET or diode detectors. As a thermometric substance of the proposed NQR sensor, copper oxide Cu₂O was used, which is characterized by a strong temperature dependence of the resonance frequency of ⁶³Cu NQR. In contrast to ³⁵Cl NQR in KClO₃, for cuprous oxide the temperature dependence of ⁶³Сu NQR frequency in the frequency range 26.621-25.658 MHz is linear in the temperature range 100-390 K. It is experimentally confirmed that the use of a low mass sample (less than 200 mg) as a thermometric substance of the proposed NQR sensor is quite sufficient for successfully observation of the resonance line at the SNR equal to 9.1 dB.

Keywords: Amplitude demodulation; Marginal oscillator; Temperature sensor; nuclear Quadrupole resonance.