Application Cases

Experiment Name: Temperature Characteristic Tests of Dual-Crystal Compensated Electric Field Sensor

Experiment Purpose: To meet the demand for miniaturized electric field sensors, a co-route lithium niobate electric field sensing scheme is proposed. The experiment obtained the basic characteristics of the co-route sensor and calibrated the time-domain and frequency-domain response characteristics of the electric field sensor. To address the need for long-term use of electric field sensors in wide temperature and humidity ranges, the impact of temperature on sensor accuracy was analyzed. Dual-crystal compensated electric field sensors and Z-axis through photoelectric field sensors were proposed. Temperature and humidity tests were conducted to obtain the wide-temperature and wide-humidity adaptability of the sensors. Finally, the strong electric field sensors with good temperature and humidity stability were applied in multiple field tests to verify the performance of the electric field sensors.

Testing Equipment: Arbitrary function generator, power amplifier, impulse voltage generator, voltage divider, oscilloscope, flat electrodes, etc.

Experiment Process:

It is challenging to obtain an electric field with a large amplitude and a wide frequency range. This paper combines two different high and low-frequency electric field signal generators as a wide-frequency source. Wide-frequency source 1: An arbitrary function generator produces a small-amplitude sine signal with a frequency of 10 Hz-20 kHz. A high-voltage amplifier generates a strong electric field. Frequency-domain calibration is used to obtain the frequency response characteristics of the electric field sensor in this frequency band. Wide-frequency source 2: A lightning impulse generator produces a steep wave electric field. The calibrated electric field and sensor output are transformed into frequency-domain signals using Fourier transform to calculate the frequency response. The frequency spectrum of the lightning impulse time-domain signal mainly ranges from 10 kHz to 2 MHz. Time-domain calibration is used to obtain the sensor's frequency response characteristics in this band. Finally, the frequency response characteristics of the strong electric field sensor in the 10 Hz-2 MHz range are obtained by combining these methods.

Figure: Electric Field Sensor Characteristic Test Platform

① Frequency Response in the 10 Hz-20 kHz Range

Based on the electric field sensor characteristic test platform shown in Figure 2.11, the frequency response of the electric field sensor in the 10 Hz-20 kHz range is measured using frequency calibration. An arbitrary function generator and a high-voltage amplifier are combined to form a voltage source that applies a 2 kV sine wave signal to the flat electrodes. The sine signal frequency is adjusted from 10 Hz to 20 kHz, while the input signal and sensor output are collected.

Figure 2: Frequency Response in the 10 Hz-20 kHz Range (with 10 kHz as the Reference)

Figure 2 describes the frequency response of the strong electric field sensor in the 10 Hz-20 kHz range. The sensor response is basically a flat line. The amplitude ratio fluctuation is less than 0.42 dB, and the phase difference is less than 8.01°. The test results show that the co-route electric field sensor has good frequency response in the 10 Hz-20 kHz range.

② Frequency Response in the 10 kHz-1 MHz Range

Based on the electric field sensor characteristic test platform, the frequency response of the electric field sensor in the 10 kHz-1 MHz range is measured using time-domain methods. A multi-parameter impulse generator produces a 3 kV peak lightning impulse voltage, which is applied to the flat electrodes to generate an impulse calibration electric field. The applied electric field and sensor output waveforms are recorded. Fourier transform is used to obtain the corresponding frequency-domain signals, and further processing is performed to obtain the sensor's frequency response characteristics in this band.

Figure 3: Frequency Response in the 10 kHz-1 MHz Range (with 10 kHz as the Reference)

Figure 3 describes the frequency response of the strong electric field sensor in the 10 kHz-1 MHz range. In the 10 kHz-500 kHz frequency range, the amplitude ratio fluctuation is less than 2.12 dB, and the phase difference is less than 51.9°. When the frequency is below 500 kHz, the sensor response remains consistent and is basically a straight line. When the frequency exceeds 500 kHz, several piezoelectric resonance frequencies cause fluctuations in the amplitude ratio and phase difference.

Experimental Results:

Combining the frequency response characteristics of the sensor in the 10 Hz-20 kHz and 10 kHz-1 MHz ranges, it is found that in the 10 Hz-500 kHz frequency range, the amplitude-frequency response fluctuation of the co-route strong electric field sensor is less than 3 dB, and the frequency response remains stable.

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