AVS 46th International Symposium
    Vacuum Technology Division Wednesday Sessions
       Session VT-WeM

Paper VT-WeM5
Inner Pressure Measurement of Turbo Molecular Pump

Wednesday, October 27, 1999, 9:40 am, Room 610

Session: Vacuum Pumping Systems
Presenter: H.-P. Cheng, Precision Instrument Development Center, National Science Council, Taiwan, ROC
Authors: H.-P. Cheng, Precision Instrument Development Center, National Science Council, Taiwan, ROC
R.-Y. Jou, Precision Instrument Development Center, National Science Council, Taiwan, ROC
J.-C. Lin, Precision Instrument Development Center, National Science Council, Taiwan, ROC
F.-Z. Chen, Precision Instrument Development Center, National Science Council, Taiwan, ROC
Y.-W. Chang, Precision Instrument Development Center, National Science Council, Taiwan, ROC
Correspondent: Click to Email
In the past decades, a lot of papers have been published to deal with the pumping mechanism of turbo molecular pump. These articles contain theoretical and experimental investigations. But there are only few of articles contain the experimental data can supply to the comparison with the theoretical models. Most of previous experimental works devoted on the measurement of pumping speed and compression ratio of one stage turbo blade structure or one whole pump. The foregoing review shows that no related work has been published to measure the pressure variation of inner pump from inlet to outlet ports. In this study, the inner pressure measurement of a new type turbo molecular pump is investigated. The pump is developed by the cooperation of Kashiyama Industries Ltd. and Precision Instrument Development Center with a desire to replace the mechanical booster pump. The experimental measurement is followed by the Japan standard JVIS-005. The flow meter method is adopted here. In order to measure the pressure variation from pump inlet to outlet, there are 9 holes with 6.5-mm inner diameter are drilled through the casing of pump along the axial direction. The distances of 9 holes from the plane of inlet port are 49.5, 79.5, 107, 127, 147, 167, 187, 207, and 227 mm. The metal gasket face seal fittings with inner diameter 3-mm are welded into the holes by TIG-Tungsten inert gas welding method. The vacuum gauges with the range of 1.E-4 to 10 torr are linked with metal gasket face seal fittings by the metal bellow tube. Six sets of inlet pressures with 1.E-4, 1.E-3, 1.E-2, 0.1, 0.5 and 1 torr are measured. The pressure variations along the axial direction are plotted versus normalized axial distance. The pressure tendency related to rotor shaped is discussed. Tendency of pressure variation of measurement and prediction is compared.