Flowing Afterglow/Langmuir Probe

Flowing Afterglow/ Langmuir Probe (D. Smith, N. G. Adams) 95-600K Truly thermal qg determined. Wide range of ion types can be studied in their ground states. Low pressure,therefore clustering inhibited. 

Flowing Afterglow/ Langmuir Probe (D.Smith, N.G.Adams) 95-600K <1 A. Truly thermal q determined Many reactions can be studied. 

X 10-8 90-550K Flowing Afterglow/ Langmuir Probe Adams et al 1984 Diffusive loss restricted upper-limit... 

A decade ago, while considerable data had been compiled on the kinetic measurement of dissociative recombination (DR) reactions of small polyatomic ions, laboratory information on the product distributions of such reactions was restricted to the results of a few merged-beam and stationary-afterglow studies on DR of C02 and of H( [157,158], and the first explorations of combined flow tube/Langmuir probe/spectroscopic detector techniques, independently pursued by Rowe and co-workers (at Rennes) [159,160] and by Adams and co-work-ers (at Birmingham, and subsequently Atlanta) [161, 162]. Considerable advances have since been made, both in measurement of recombination coefficients (particularly for larger ions) and in the elucidation of product distributions for a still small but growing sample of important IS ions. 

Figure 7. Schematic diagram of a flowing-afterglow electron-ion experiment. The diameter of flow tubes is typically 5 to 10 cm and the length is 1 to 2 meters. The carrier gas (helium) enters through the discharge and flows with a velocity of 50 to 100 m/s towards the downstream end of the tube where it exits into a fast pump. Recombination occurs mainly in the region 10 to 20 cm downstream from the movable reagent inlet, at which the ions under study are produced by ion-molecule reactions. The Langmuir probe measures the variation of the electron density in that region. A differentially pumped mass spectrometer is used to determine which ion species are present in the plasma.

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