磁层电场仪前端信号处理电路研究

Abstract: A kind of front-end signal processing circuit of the electric field instrument, which would be used in the Earth's magnetosphere measurement, is investigated and presented in this work. The double-probe electric field instrument outputs drive current to the ambient plasma environment, and measures the potential difference between the two probes to detect the electric field. Plasma impedance of the magnetosphere is high, so the probe of the electric field instrument will operate in a high voltage to match the electric current requirement. When the operating voltage is close to or surpasses the circuit threshold voltage, the measuring results would be affected, and the instrument will be possibly damaged. This paper adopts voltage scheme with low bias current and feedback floating power supply control scheme, to solve the weak current sampling problem and high dynamic potential handling problem in measuring the electric field of a thin plasma. Test results show that the circuit can make the probe adapt to the floating ground in the dynamic voltage range of 100 V, and measure the electric field from DC to 150kHz, with a low noise level below 14nV?mHz~(-1/2), which meets the needs of electric field measurements in magnetosphere.