Artificial Intelligence and Resonance Spectroscopy

The electromagnetic resonance method is based on generating an alternating electromagnetic field within the region occupied by the test specimen. This field acts as the coupling medium between the resonant circuit and the specimen under investigation. On the one hand, the resonant circuit serves as the emitter of the electromagnetic field, while on the other hand, it functions as the receiver (sensing element) of the field perturbations introduced by the specimen.

Even in the absence of a test specimen, the alternating electromagnetic field generated by the solenoid consists of the superposition of two electromagnetic fields that vary in antiphase. One field arises from the variation of the solenoid's magnetic flux density and gives rise to a rotational electric field in accordance with the Maxwell–Faraday equation. The other originates from variations in the electric field created by the potential difference either between the outermost turns of the solenoid (when the specimen is placed inside the solenoid) or between the turn nearest to the specimen surface and the specimen itself (when the specimen is positioned opposite the end face of the solenoid). This field generates a rotational magnetic field according to Ampère's circuital law with Maxwell's correction.

When exposed to the external alternating electromagnetic field, the test specimen may exhibit various electrically induced phenomena depending on its physical nature. These include linear and eddy conduction currents, linear and eddy displacement currents, as well as linear and eddy ionic currents associated with the ordered motion of ions. According to the principle of electromagnetic field superposition, these induced phenomena perturb the external electromagnetic field.

The resulting field perturbations are detected by the solenoid of the resonant sensor. Consequently, the resonant circuit containing the solenoid behaves as though additional circuit elements - a capacitor, an inductor, and a resistor - had been incorporated into the circuit. The combined capacitive, inductive, and resistive contributions constitute an additional impedance introduced by the test specimen. This additional impedance is the primary measurable attribute of the resonant sensing system.

Variations in the parameters of the resonant circuit are manifested as changes in its frequency response, particularly in the resonant frequency and resonance amplitude. By analyzing these changes, the electrical impedance of the test specimen can be determined, providing a basis for real-time, non-contact monitoring and characterization of materials and technological processes.