skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Apex Dips of Experimental Flux Ropes: Helix or Cusp?

Abstract

We present a new theory for the presence of apex dips in certain experimental flux ropes. Previously such dips were thought to be projections of a helical loop axis generated by the kink instability. However, new evidence from experiments and simulations suggest that the feature is a 2D cusp rather than a 3D helix. The proposed mechanism for cusp formation is a density pileup region generated by nonlinear interaction of neutral gas cones emitted from fast-gas nozzles. The results indicate that density perturbations can result in large distortions of an erupting flux rope, even in the absence of significant pressure or gravitational forces. The density pileup at the apex also suppresses the m = 1 kink mode by acting as a stationary node. Consequently, more accurate density profiles should be considered when attempting to model the stability and shape of solar and astrophysical flux ropes.

Authors:
; ;  [1];  [2];  [3]
  1. Applied Physics, California Institute of Technology, Pasadena, CA 91125 (United States)
  2. Theoretical Division, Los Alamos National Laboratory, Mail Stop B227, Los Alamos, NM 87545 (United States)
  3. Mathematical Modeling and Analysis, Los Alamos National Laboratory, Mail Stop B284, Los Alamos, NM 87545 (United States)
Publication Date:
OSTI Identifier:
22679750
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 848; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; DENSITY; DISTURBANCES; EMISSION; INTERACTIONS; KINK INSTABILITY; MAGNETOHYDRODYNAMICS; NONLINEAR PROBLEMS; PERTURBATION THEORY; PLASMA; SIMULATION; STABILITY; SUN; THREE-DIMENSIONAL CALCULATIONS; TWO-DIMENSIONAL CALCULATIONS

Citation Formats

Wongwaitayakornkul, Pakorn, Haw, Magnus A., Bellan, Paul M., Li, Hui, and Li, Shengtai, E-mail: pwongwai@caltech.edu, E-mail: mhaw@caltech.edu. Apex Dips of Experimental Flux Ropes: Helix or Cusp?. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA8990.
Wongwaitayakornkul, Pakorn, Haw, Magnus A., Bellan, Paul M., Li, Hui, & Li, Shengtai, E-mail: pwongwai@caltech.edu, E-mail: mhaw@caltech.edu. Apex Dips of Experimental Flux Ropes: Helix or Cusp?. United States. doi:10.3847/1538-4357/AA8990.
Wongwaitayakornkul, Pakorn, Haw, Magnus A., Bellan, Paul M., Li, Hui, and Li, Shengtai, E-mail: pwongwai@caltech.edu, E-mail: mhaw@caltech.edu. Fri . "Apex Dips of Experimental Flux Ropes: Helix or Cusp?". United States. doi:10.3847/1538-4357/AA8990.
@article{osti_22679750,
title = {Apex Dips of Experimental Flux Ropes: Helix or Cusp?},
author = {Wongwaitayakornkul, Pakorn and Haw, Magnus A. and Bellan, Paul M. and Li, Hui and Li, Shengtai, E-mail: pwongwai@caltech.edu, E-mail: mhaw@caltech.edu},
abstractNote = {We present a new theory for the presence of apex dips in certain experimental flux ropes. Previously such dips were thought to be projections of a helical loop axis generated by the kink instability. However, new evidence from experiments and simulations suggest that the feature is a 2D cusp rather than a 3D helix. The proposed mechanism for cusp formation is a density pileup region generated by nonlinear interaction of neutral gas cones emitted from fast-gas nozzles. The results indicate that density perturbations can result in large distortions of an erupting flux rope, even in the absence of significant pressure or gravitational forces. The density pileup at the apex also suppresses the m = 1 kink mode by acting as a stationary node. Consequently, more accurate density profiles should be considered when attempting to model the stability and shape of solar and astrophysical flux ropes.},
doi = {10.3847/1538-4357/AA8990},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 848,
place = {United States},
year = {2017},
month = {10}
}