Parallel auto-pumping control of vacuum system on TEM

For the normal operation of TEM, the required vacuum must be achieved in order to avoid the interaction of electrons and gas molecules within column. According to the vacuum demand of the normal operation of TEM, the vacuum system structure is marked out, then the pumping flow is designed which adopt parallel pumping method of vacuum pump. This method shortens the pumping time and heightens the use efficiency of vacuum pump. For actualizing automatic pumping, the pumping object of vacuum pump is exchanged by controlling open or close of isolation valve with PLC by computer programming. Finally, the measurement results indicate that vacuum system can fulfil the pre-established vacuum demand.