title: A new instrument for thermal electron attachment at high temperature: NF3 and CH3Cl attachment rate constants up to 1100 K.
abstract: A new high temperature flowing afterglow Langmuir probe (HT-FALP) apparatus is described. A movable Langmuir probe and a four-needle reactant gas inlet were fitted to an existing high temperature flowing afterglow apparatus. The instrument is suitable for study of electron attachment from 300-1200 K, the upper limit set to avoid softening of the quartz flow tube. We present results for two reactions over extended ranges: NF(3) (300-900 K) and CH(3)Cl (600-1100 K). Electron attachment rate constants for NF(3) had been measured earlier using our conventional FALP apparatus. Those measurements were repeated with the FALP and then extended to 900 K with the HT-FALP. CH(3)Cl attaches electrons too weakly to study with the low temperature FALP but reaches a value of approximately 10(-9) cm(3) s(-1) at 1100 K. F(-) is produced in NF(3) attachment at all temperatures and Cl(-) in CH(3)Cl attachment, as determined by a quadrupole mass spectrometer at the end of the flow tube. Future modifications to increase the plasma density should allow study of electron-ion recombination at high temperatures.
authors.affiliation: Air Force Research Laboratory, Space Vehicles Directorate, 29 Randolph Road, Hanscom Air Force Base, Massachusetts 01731-3010, USA.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Miller
authors.forename: Jeffrey F
authors.initials: JF
authors.lastname: Friedman
authors.forename: John S
authors.initials: JS
authors.lastname: Williamson
authors.forename: Linda C
authors.initials: LC
authors.lastname: Schaffer
authors.forename: A A
authors.initials: AA
authors.lastname: Viggiano