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Title: Discrete helical modes in imploding and exploding cylindrical, magnetized liners

Discrete helical modes have been experimentally observed from implosion to explosion in cylindrical, axially magnetized ultrathin foils (B z = 0.2 - 2.0 T) using visible self-emission and laser shadowgraphy. The striation angle of the helices, phi, was found to increase during the implosion and decrease during the explosion, despite the large azimuthal magnetic field (>40 T). Here, these helical striations are interpreted as discrete, non-axisymmetric eigenmodes that persist from implosion to explosion, obeying the simple relation $$\phi$$ = 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.
Authors:
 [1] ;  [1] ; ORCiD logo [1] ; ORCiD logo [1] ;  [1] ;  [1] ; ORCiD logo [1]
  1. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences
Publication Date:
Grant/Contract Number:
SC0012328; DGE 1256260; FA9550-15-1-0419
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 23; Journal Issue: 12; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Nuclear Engineering and Radiological Sciences
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF); US Air Force Office of Scientific Research (AFOSR)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
OSTI Identifier:
1465361
Alternate Identifier(s):
OSTI ID: 1334553