The current measurement and control system in a Low-frequency Magnetic Field is a comprehensive system of hardware and software, including two parts: current measurement and computer control.
Vacuum micro-electronics devices, which are based on field emission theory, are more and more widely applied, because of their low power consumption, high current density and high frequency.
以场致发射理论为基础的真空微电子器件，因其具有功耗低、电流密度大、频率高等诸多优点而倍受人们关注。
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The current situation, present questions, future research direction of effects and application of extremely lowfrequency electromagnetic field on human health are introduced in this paper.