Accession Number : AD0718430

Title :   Diffusion Plasmas and Diffusion.

Descriptive Note : Final rept.,

Corporate Author : QUEEN'S UNIV BELFAST (NORTHERN IRELAND) DEPT OF PHYSICS

Personal Author(s) : Emeleus,K. G.

Report Date : DEC 1970

Pagination or Media Count : 18

Abstract : The mechanism of diffusion, and some boundary problems, have been investigated in both electropositive (ep) and electronegative (en) gases. A method is described for distinguishing between diffusion-dominated and recombination-dominated ep negative glows, recombination being either collisional-radiative or dissociative in practice. In an ep negative glow and Faraday dark space, the mode of diffusion changes from nearly ambipolar to nearly free as the wall sheath expands on proceeding away from the cathode, until the resulting throttling is relieved by formation of a positive column via an intermediate shock-like layer and complex double space-charge. Diffusion into a side-arm involves a similar ambipolar to free transition with unrelieved closure. A survey made of the literature on production of metastable atoms and molecules in discharge tubes has shown that whilst a wide range of discharge forms may be employed, conditions in few are known in sufficient detail for plasma data to be used with confidence in deriving forbidden radiation lifetimes and quenching collision cross-sections. (Author)

Descriptors :   (*PLASMA MEDIUM, DIFFUSION), (*ATMOSPHERES, AURORAE), GAS DISCHARGES, IONIZATION, ELECTRON DENSITY, PLASMA SHEATHS, PROBES, GREAT BRITAIN

Subject Categories : Atmospheric Physics
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE