Standard Practice for Determining Vacuum Chamber Gaseous Environment Using a Cold Finger

Importancia y uso:

5.1 When applied in the case in which there is no test item in the vacuum chamber (such as during bake-out operations), this procedure may be used to evaluate the performance of the vacuum chamber in relation to other data from the same or other chambers given that critical parameters (for example, length of exposure, temperature of the chamber and cold finger, anisotropy, and so forth) can be related.

5.2 The procedure can be used to evaluate the effects of materials found in the residue on items placed in the vacuum chamber.

5.3 The procedure can be used to describe the effect of a prior test on the residual gases within a vacuum chamber.

5.4 By selecting the time at which the coolant is introduced into the cold finger, the environment present during a selected portion of a test can be characterized. This can be used to determine the relative efficacy of certain vacuum chamber procedures such as bake-out.

5.5 The procedure may be used to define the outgassed products of a test item that condense on the cold finger.

5.6 The procedure may be used in defining the relative cleanliness of a vacuum chamber.

5.7 In applying the results of the procedure to the vacuum chamber in general, consideration must be given to the anisotropy of the molecular fluxes within the chamber.

5.8 The procedure is sensitive to both the partial pressures of the gases that form the condensibles and the time of exposure of the cold finger at coolant temperatures.

5.9 The procedure is sensitive to any losses of sample that may occur during the various transfer operations and during that procedure wherein the solvent is evaporated by heating it on a steam bath.

Note 1: Reactions between solvent and condensate can occur and would affect the analysis.

Subcomité:

E21.05

Referida por:

E2900-24

Volúmen:

15.03

Número ICS:

23.160 (Vacuum technology)

Palabras clave:

cold finger; contamination monitoring; residual gas compositions; vacuum chamber;