... old fashioned equipmentFeature:Economical use,polytechnic index maturityConfiguration: Vacuum pump,vacuum instrument,temperature-control instrument,cylinder gas,stainless stell's ... valve and pipe.Explanation:1. Diffusion pump's vacuum degree is as high as 5 millimeters mercury,obtiate ... gas in the light tube thorough and quickly.2. Vacuum degree,charge quantity and the bombardment obviate degree are ...