| 摘要 |
Vacuum gauge that detects and measures the partial pressure of a gas in a chamber, from pressures ranging from atmospheric to ultra-high vacuum. The gauge utilizes electromagnetic radiation, that is generated in the vacuum chamber by a electromagnetic radiation source. When the partial pressure of water vapor is being measured, the light source used emits low wavelength UV light in the 184 and 254 nanometer range. For other gases, different light sources emitting different UV wavelengths or different electromagnetic radiation are used. The electromagnetic radiation traverses the interior of the vacuum chamber, and impinges upon a detector. As this light passes through the interior space between the source and the detector, it strikes the particular, residual gas molecules that are being detected. These impacts scatter the light and/or absorb the light, so that there is less photonic energy striking the detector. The greater the number of molecules (the higher pressure) the lower the amount of energy that strikes the detector. Thus, the energy striking the detector is a measure of the partial pressure of the particular gas. In the preferred embodiment, for measuring the partial pressure of water vapor, the gauge-apparatus of the invention utilizes an ultraviolet light source that is surrounded by a hollow cylinder made of nickel, which serves as a detector element via the photoelectric effect.
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