| 释义 |
impactor|ɪmˈpæktə(r)|
Also impacter.
[f. impact v.: see -or, -er1.]
1. A device or machine that delivers impacts or blows.
1916Chambers's Jrnl. Dec. 830/2 The impactor golf-machine is a new invention. 1950J. H. Perry Chem. Engineers' Handbk. (ed. 3) 1129/2 The Impactor..is a reversible hammer crusher without a discharge grating or cage. 1966McGraw-Hill Encycl. Sci. & Technol. V. 471/1 To increase the effectiveness of the forging blows, the impacter forging machine was developed.
2. An impinger, esp. one in which the particles are deposited on a dry surface rather than in a liquid.
The distinction between impactors and impingers explained in quot. 1945 is rarely made.
1945K. R. May in Jrnl. Sci. Instrum. XXII. 187 (heading) The cascade impactor: an instrument for sampling coarse aerosols. Ibid. 188 The method which has been adopted for depositing the sample is direct impaction of the particles on to glass slides which may be coated with a suitable medium... The terms ‘impactor’ and ‘impaction’ were suggested by Prof. J. H. Gaddum to avoid confusion with ‘impinger’ instruments... In ‘impingers’ a fine jet of air is directed at very high speed on to a flat surface to obtain the maximum efficiency of deposition of small particles. In the case of ‘impactors’ jet speeds are lower and larger particles are dealt with. 1956P. L. Magill et al. Air Pollution Handbk. x. 30 Most cascade impactors are now operated using high air velocities. Ibid. 29 A single-stage impactor..is often useful because of its simplicity of operation. 1964[see impact v. 4]. 1971Nature 12 Feb. 501/1 Partition of single uredospores between the first and second stage of a cascade impactor indicated a terminal velocity of 0·6 cm s—1. |