Research Of Key Technology Of Seismic Sensors Used In High Temperature

Socio-economic development and the accelerating process ofurbanization give rise to the increasing level of environment noise. This lead toless places exist, which were suitable for the construction of the seismicstations. Thus it is an effective way to avoid surface interference sources bydeveloping the technology of deep borehole observation. However, there aremany technical problem need to solve, such as the ability of the instrument toendure high temperature and high pressure and signal attenuation duringlong-term transmission.It is common for the temperature up to150℃in the observation well for thetemperature increase rate can reach up to10~30℃/km. The reliability andservice life of instrument will be significantly decreased when the temperatureis higher than the rated temperature of the apparatus. Thus it is crucial toresearch on high-temperature seismograph.Force feedback technology is the core technology which is widely used instrong earthquake observation stations and the earthquake networks center toachieve wide observation frequency band, large dynamic range and lowinstrument noise. Therefore, the force balance accelerometer were studied, torealize the aims that not only the sensitivity and amplitude-frequencycharacteristic of force balance accelerometer were ensured, but also the hightemperature resistance of130℃.After studying the principles of force balance accelerometer, the importantfunction of the circuit and the auxiliary circuit were remade and replacedrespectively using the high temperature discrete component. Considering thereliability of the design, the high temperature circuit was designed after theroom temperature circuit debugging successfully firstly.Successfully debugging in the laboratory is the foundation of thehigh-temperature test, aims to verify the work ability of the testing machine under high temperature and the characteristics of sensitivity andamplitude-frequency to satisfy the network access index.The test results showed that he testing machine can work effectively in130℃.The amplitude-frequency characteristic of the testing machine canmeet the requirements of the design in normal temperature (60℃,100℃and130℃).The research results indicated that the High-temperature force balanceaccelerometer design is feasible and effective. It is hopeful to designs andimplementation of the methods of High-temperature seismograph to promotethe development of motion observation in many fields, such as deep boreholeobservation and vibration monitoring of nuclear power plant.