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

1.1 This practice covers a technique for collecting samples of materials that are part of the residual gas environment of an evacuated vacuum chamber. The practice employs a device designated as a "cold finger" that is placed within the environment to be sampled and is cooled so that constituents of the environment are retained on the cold-finger surface.

1.2 The practice covers a method for obtaining a sample from the cold finger and determining the weight of the material removed from the cold finger.

1.3 The practice contains recommendations as to ways in which the sample may be analyzed in order to identify the constituents that comprise the sample.

1.4 By determining the species that constitute the sample, the practice may be used to assist in defining the source of the constituents and whether the sample is generally representative of samples similarly obtained from the vacuum chamber itself.

1.5 This practice covers alternative approaches and usages to which the practice can be put.

1.6 The degree of molecular flux anisotropy significantly affects the assurance with which one can attribute characteristics determined by this procedure to the vacuum chamber environment in general.

1.7 The temperature of the cold finger significantly affects the quantity and species of materials collected.

1.8 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific precautionary statements, see Section 8.