Measurement of electron attachment processes in a high-temperature plasma

Abstract

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> formation from N <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O varies from about 3 to 9×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /s over the temperature range of 2400-3000°K while the rate constant for F <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> formation from SF <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</inf> varies from 2.8 to 4×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> /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.