ターボ分子ポンプの性能表記に関する考察

抄録

  Turbomolecular pump is featured by mainly two performance, they are pumping speed (or volume flow rate) and ultimate pressure, which mean how fast and how lower the pressure pump can evacuate a vacuum chamber, respectively. The measurement methods of these pump's characteristics are specified in the JAPANESE INDUSTRIAL STANDARDS (JIS B 8328), and specific numerical values are provided by turbo molecular pump's manufacturers.
  These days, the turbomolecular pump that has the ability to handle larger rate of gas under low vacuum is required in the field of semiconductor and liquid-crystal display panel device manufacturing, for example. This kind of pump's performance characteristics are expressed by the terms such as the maximum throughput, maximum working pressure, maximum backing pressure, critical backing pressure and so on. But recently, the definitions in the manufacture's specifications do not always coincide each other, and sometimes seems different from relevant standards.
  In this report, we refer to the current standards with regard to turbomolecular pumps performance characteristics and related terms, and refer to concerns about definitions of the maximum backing pressure, ultimate pressure and maximum throughput which seem especially inaccurate in terms of the definition of terms and way of expression.