Reflection of Background Ions by an Expanding Laser-Produced Plasma.
Abstract
A mass-spectroscopic study of a precursor feature, which propagates ahead of a laser-produced plasma expanding into a partially ionized background, has confirmed that the feature comprises fast ions of the background gas species. The maximum velocity of the precursor ions is found to be V(MAX) about = 2 mu/M (V sub LE), where mu/M is the ratio of reduced mass to background ion mass and (V sub LE is the leading edge velocity of the laser-produced plasma; the precursor ions therefore appear to result from two-body collisions. A theoretical model which includes screened-nuclear cross-sections and friction due to multiple small-angle collisions indicates that hard-knock ion-ion collisions are insufficient to explain the large precursor ion flux which is experimentally observed. The experimental results are in satisfactory agreement with a model which invokes ion-neutral rearrangement collisions for generation of the precursor ions. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1973
- Accession Number
- AD0766893
Entities
People
- David W. Koopman
- Robert R. Goforth
Organizations
- University of Maryland