Research On A Micro-current Amplifier In The Fast Ionization Gauge Of Strong Anti-interference

The measurement of the neutral gas pressure (density) is significant in the study of the controlled thermonuclear fusion and plasma physics. One of the important contents in research of the key techniques in the divertor was to measure the neutral gas pressure in real time, quickly and accurately. In this paper the circuit design and experiment research of a micro-current amplifier in the fast ionization gauge of anti-electromagnetic interference and real-time measurement were conducted.Basing on the design methods of the weak ion flow amplifying in the fast gauge, I analyzed the characteristics of the ion flow in the fast ionization gauge of strong anti-interference, studied the implementation method of the weak signal detection, selected the implementation of micro current measurement reasonably and designed the micro ion current signal amplifier of the fast gauge. This amplifier is made up of multiple units:high precision, high stability of I/U conversion circuit with a deep negative feedback, integrated filter to remove power frequency noise and other interfering signals, PLL produced the same frequency and phase signal with the measured signal and phase sensitive detector, low pass filter and programmable gain amplifier, etc.By means of a series of electronic design automation (EDA), I completed the ion flow amplifier electrical principle diagram design and simulated each unit of the amplifier, then analyzed regulating characteristics of the circuit and obtained the amplification characteristics, optimized the circuit performance and verified the feasibility and reliability of scheme.At last the experimental study of the programmable gain amplifier (PGA) was carried out. A single chip computer development board was used to match The A/C converter, etc. and the amplifier and its interface circuits with MCU were built, then the single-chip control program was written. Debug to run the circuit module to achieve the collection, store and display of the data and its automatic selection of the amplifier gain.