SPACE CHARGE AND IONIZATION REGIONS NEAR THE ARC CATHODE.
Abstract
A model for the cathode drop region of an arc on refractory cathodes is formulated. Briefly, there are four regions. In region I both the positive ions and electrons fall freely. In region II, the emitted electrons fall freely but the ions and back diffused electrons suffer collisions. Region III is the ionition region where the electron current density and ion current denstiy are not conserved. Region IV is the contracted region of the plasma. In order to account for the ion current density in a mobility controlled space charge region, means must be found to treat the ionic motion. This problem, which has not been attempted heretofore, requires a complex formulation. However, the results are important. It is shown that diffu sion due to concentration gradient is more im portant than electric mobility in accounting for the ionic current density. This is true in regions II and III. It is also shown that the relaxation time of the electrons is so short that ionization in region III can be treated by a thermal mechanism. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1963
- Accession Number
- AD0418764
Entities
People
- Allan Greenwood
- T.h. Lee
Organizations
- General Electric