A STUDY OF THE ION WAKE OF AN ELECTRON BEAM IN A FREE JET,
Abstract
A narrow beam of 10-50 KV electrons is coming into wide use as a probe of rarefied gas flows. Such a beam forms ions in many gases, including nitrogen. These ions form a stream, or wake, downstream of the beam. This work is a study of such a wake in a free jet of nitrogen, for the purpose of finding, if possible, conditions under which information about the state of the gas may be inferred from the behavior of the wake. Relations are derived between the wake flux cross-section and gas lateral and axial temperatures at the beam. Perturbations due to collisions and induced fields are considered. An ion wake is found experimentally, using as a probe a conductor at the local flow potential. The flux cross-section of the wake is shown to consist of two components, one proportional to gas density at the beam, the other approximately independent of gas density. The density-dependent component shows approximate agreement with theory. The constant component is discussed and some suggestions as to its origin are advanced. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1968
- Accession Number
- AD0679631
Entities
People
- Donald W. Harvey
Organizations
- University of Southern California