Schlieren observations of density channels in MPPE [electronic resource].
- Published:
- Washington, D.C : United States. Dept. of Energy. Office of the Assistant Secretary for Defense Programs, 1990.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy. - Physical Description:
- Pages: (6 pages) : digital, PDF file
- Additional Creators:
- Lawrence Livermore National Laboratory
United States. Department of Energy. Office of the Assistant Secretary for Defense Programs
United States. Department of Energy. Office of Scientific and Technical Information - Access Online:
- www.osti.gov
- Summary:
- Schlieren imaging techniques were used to study the density depressions created by the ATA electron beam 37 cm after the entrance foil. Typical channel depressions were 5--10% of ambient density per pulse. Under IFR guiding channel depths as deep as 30% were seen on single pulse operation. Pulse 5 of the 5 pulse burst has passed through a channel reduced to 30% of ambient density. To lowest order, one would expect channel density depressions to scale as (Δn/n) {proportional to} ({number sign} of pulses * I{sub beam}/channel area). Channel depth observations scaled roughly with beam current, {number sign} of pulses, and inversely with channel area. Pressure scaling was anomalous in that Δn appeared to be less sensitive to pressure than the linear dependence expected. This would require that the energy deposition (stopping power) is independent of pressure and is a surprising result which can only be explained with collective effects. Scaling of channel expansion rates with pressure suggest classical diffusion (D {proportional to} 1/n) for times up to 200 mS. During these early times, the diffusion constant was, however, 3--5 times larger than the classical value. At later times, large scale turbulence was observed and the effective diffusion constant increased by an order of magnitude. This turbulence seemed to develop more quickly for deeper channels.
- Subject(s):
- Note:
- Published through SciTech Connect.
09/28/1990.
"ucrl-jc-105078"
" conf-9006228--7"
"DE91005419"
1990 annual charged particle beam meeting, San Diego, CA (USA), 11-14 Jun 1990.
Guethlein, G.; Pechacek, B. - Funding Information:
- W-7405-ENG-48
View MARC record | catkey: 14694751