An Initial Study of the Injection of an Intense Relativistic Electron Beam into the Atmosphere.
Abstract
Using the VEBA pulse generator (approx. or less than 2 MV, approx 60 kAmp, approx. 60 ns) and a field emission diode with a titanium foil anode (approx. 43 micrometers), relativistic electron beams with v/y approx. 0.5 have been produced and injected into the atmosphere. Typical injected net currents were approx. 35 kAmps and there was little plasma return current (approx. or less than 20%). These beams were observed to expand and contract at the betatron wavelength lambda sub beta approx. 12 cm) as they propagated through the atmosphere and to become unstable at approx. lambda sub beta. Observations were made in both visible light (2000-6000 Angstroms and x-radiation (10-100 keV). Peak current densities reached approx. 3kAmp/sq. cm. at approx. 20 cm from the diode where the beam appeared to consist of two separate coaxial components both of near uniform current density. The central component contained approx. 65% of the total beam current and was initially within a radius of approx. 1.4 cm. The outer component of the beam started with a radius of approx. 5 cm (defined by the anode foil) and appeared to expand steadily. The visible emissions belonged to the species N2 and N2+ and were synchronous with the electron beam current. The absolute emission in the band N2+ 1N(0-0) agreed with the calculated fluorescence intensity within experimental uncertainty, but the emission in the band N(2)2P(0-0) was approx 6 times larger than suggested by simple fluorescence calculations. A simple technique was devised to select a fraction of the electron beam emerging from the diode to produce a pinched matched beam. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 04, 1981
- Accession Number
- ADA098896
Entities
People
- I. M. Vitkovitsky
- Joseph R. Greig
- M. Herndon
- R. B. Fiorito
- Richard F. Fernsler
Organizations
- United States Naval Research Laboratory