Measurement of electron attachment processes in a high-temperature plasma

An experimental technique has been developed for measuring rate constants of electron attaching reactions as well as ion-molecule reactions in plasma at 2000-3000°K. Reaction product ions are mass analyzed and rate constants are obtained from plots of the collected ion current. The rate constant for O
^-
formation from N
2
O varies from about 3 to 9×10
^-9
cm
³
/s over the temperature range of 2400-3000°K while the rate constant for F
^-
formation from SF
6
varies from 2.8 to 4×10
^-10
cm
³
/s for temperatures from 2775 to 3000°K. A brief survey of experimental techniques for measuring electron attachment rate constants at lower temperatures is also given, together with a comparison of these rate constants and present high-temperature values.