Retrograde motion of a positive column of low pressure discharge

Abstract

The motion of a positive column of low pressure discharge passing through the annulus between coaxial glass tubes and subjected to a transverse magnetic field has been investigated. The positive column was photographed and measured optically, and was found to move in the retrograde direction. Variation in this retrograde motion with tube geometry, discharge current and gas pressure was measured and examined based on the ‘‘neutral drag instability theory’’ of Hoh and Simon.