Research And Development Of Measure And Control Vacuum System For Mass Spectrograph

It has been more than 90 years about the mass spectrograph development. At present, mass spectrograph has been widely used in basic science research, national defence, spaceflight and other fields. Therefore, it is significant to develop mass spectrograph with the independent intellectual property. The research content is to develop a test and control system to test vacuum value in the mass spectrograph.At present, there are also a lot of vacuum measurement products at home and abroad, There are many shortcomings for the development of mass spectrometry of these products. 1. Most of the vacuum gauge controller can not measure vacuum at inside of mass spectrometry because of there bigger size. 2. It greatly enhanced the cost of the design of mass spectrometers for expensive price. 3. They do not have General performance, so every vacuum gauge required for each specific type of controller to control. 4. Lack of the integrated product of vacuum measurement and control, can not adjust the vacuum degree when measuring the vacuum.The system is a vacuum measurement and control system, which supply a gap above and provide requirements of the development of mass spectrometry at the present time. At present, the system can control and measure several vacuum gauges which in Mass Specrometry office of National Institute of Metrology P.R.China. It includes 925C and 979 made in MKS Instruments, Micro-Ion Plus made in Helix Technology Corporation, PKR251 made in PFEIFFER company, ZJ-14B made in Zhenghua company. At the same time, the system can control turbomolecular drag pump made in PFEIFFER company to regulate vacuum degree.The key to control ZJ-14B is collecting it`s discharge current, then calculate vacuum degree according to it`s discharge current formula. The key to control PKR251 is measuring voltage in it`s circuit, then immediately vacuum degree according formula. The measuring results would be send to control system and PC, and show the result in LCD which is very convenient to monitor. The key to control other gauges and turbomolecular drag pump is according to serial ports to communicate. Serial ports communication includes RS232 and RS485. The system communicate with Several gauges and PC is according RS232 communication protocol, communicate with some other gauges and turbomolecular drag pump is according RS485 communication protocol. This part distribute different address to recognize the model of the gauge.The microprocessor in system is MSP430F1611, which can good achieve controlling work of system for it`s strong ability to process, ultra-low-power mode, Rich on-chip peripheral modules. It is mainly responsible for controlling the high voltage power supply and amplifier range and data processing and serial communication. The software of MSP430 includes range switch, data acquisition, data processing and communications with the PC monitoring and control systems.Anti-magnetron cold cathode ionization vacuum gauge has many advantages, such as structure is simple, no filament, do not afraid of exposure to the atmosphere and a wide range. So it is a very commonly used vacuum gauge in mass spectrometer. Because of it`s measurement parameters are unknown, it is a important content that test of cold cathode ionization vacuum gauge.This article writes detailed test results of PKR251 and ZJ-14B. For PKR251, we have finished comparison test with the controller of PFEIFFER. For ZJ-14B, we measured a large number of data in a long time. Considering the impact of environment on system testing, the article gives a detailed test result of parameters, and compared vacuum degree testing results with Micro-Ion which is as a reference standard.