Discrete helical modes in imploding and exploding cylindrical, magnetized liners
Abstract
Discrete helical modes have been experimentally observed from implosion to explosion in cylindrical, axially magnetized ultrathin foils (Bz = 0.2 – 2.0 T) using visible self-emission and laser shadowgraphy. The striation angle of the helices, ϕ, was found to increase during the implosion and decrease during the explosion, despite the large azimuthal magnetic field (>40 T). These helical striations are interpreted as discrete, non-axisymmetric eigenmodes that persist from implosion to explosion, obeying the simple relation ϕ = m/kR, where m, k, and R are the azimuthal mode number, axial wavenumber, and radius, respectively. Experimentally, we found that (a) there is only one, or at the most two, dominant unstable eigenmode, (b) there does not appear to be a sharp threshold on the axial magnetic field for the emergence of the non-axisymmetric helical modes, and (c) higher axial magnetic fields yield higher azimuthal modes.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 01, 2016
- Source ID
- 10.1063/1.4969082
Entities
People
- Adam Steiner
- D. A. Yager-elorriaga
- Nicholas Jordan
- P. C. Campbell
- Po Zhang
- Ronald Gilgenbach
- Y. Y. Lau
Organizations
- Air Force Office of Scientific Research
- Division of Graduate Education
- Sandia National Laboratories
- United States Department of Energy
- University of Michigan