Gas friction vacuum meter and method of making measuring body
AssigneeKernforschungsanlage Julich Gesellschaft mit beschrankter Haftung
InventorsJohan K. Fremerey, Bernd Lindenau
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Abstract
A rotary measuring body for a gas-friction vacuum meter has its surface formed with a macroscopic roughness which provides a gas-friction coefficient minimally affected by the microscopic roughness of the surface. As a result, the output signal and sensitivity of the vacuum meter is high and is less susceptible to change as a result of surface corrosion.
Claims7
In a gas-friction vacuum meter wherein a rotating body is suspended with low bearing friction in a measuring member communicating with an evacuated vessel and braking of rotary movement of said body by impingement by gas molecules against a surface of said body is measured, the improvement wherein said body has a uniform macroscopic roughness of said surface sufficient to impart a gas-friction coefficient to said surface which is substantially unaffected by microscopic roughness of said surface.
In a method of making a rotary measuring body for a gas-friction vacuum meter, the improvement which comprises the steps of:
- (a) macroscopically roughening a surface of said body;
- (b) putting said body with said macroscopically roughened surface and a body with no gas-friction coefficient in respective vacuum meters communicating with a common vessel at low pressure;
- and
- (c) determining the relative braking of rotations of said bodies to establish the relative gas-friction coefficient of the body with the macroscopically roughened surface.
Dependencies are inferred from the claim text.