Accession Number : AD0718547

Title :   Longitudinal Diffusion Coefficients Misnamed,

Corporate Author : LOCKHEED MISSILES AND SPACE CO PALO ALTO CALIF LOCKHEED RESEARCH LAB

Personal Author(s) : Varney,Robert N.

Report Date : 10 AUG 1970

Pagination or Media Count : 2

Abstract : In ion drift velocity measurements, the spread in arrival time of the drifting ions has led to evaluation of a so-called longitudinal diffusion coefficient, D(L). It is shown that the spread in arrival times is attributable to the simple statistical fluctuation associated with addition of many nearly random free paths. On this basis, the value of D(L) derived from the data on the assumption that a true diffusion, dependent on an ion density gradient, is involved is shown to rise as the square of the drift velocity. Such a rise is observed experimentally, setting in when the drift velocity exceeds a minimum value. The real diffusion coefficient is then less than that reported as D(L). (Author)

Descriptors :   (*IONS, DIFFUSION), GASES, MATHEMATICAL ANALYSIS, STATISTICAL MECHANICS

Subject Categories : Physical Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE