@article{FeudelGellertRuedigeretal.2003,
  author    = {Feudel, Fred and Gellert, Marcus and R{\"u}diger, Sten and Witt, Annette and Seehafer, Norbert},
  title     = {Dynamo effect in a driven helical flow},
  year      = {2003},
  language  = {en}
}
@article{DemircanSeehafer2002,
  author    = {Demircan, Ayhan and Seehafer, Norbert},
  title     = {Dynamo in asymmetric square convection},
  issn      = {0309-1929},
  year      = {2002},
  language  = {en}
}
@article{DemircanSeehafer2001,
  author    = {Demircan, Ayhan and Seehafer, Norbert},
  title     = {Dynamos in rotating and nonrotating convection in the form of asymmetric squares},
  year      = {2001},
  abstract  = {We study the dynamo properties of asymmetric square patterns in Boussinesq Rayleigh-B'enard convection in a plane horizontal layer. Cases without rotation and with weak rotation about a vertical axis are considered. There exist different types of solutions distinguished by their symmetry, among them such with flows possessing a net helicity and being capable of kinematic dynamo action in the presence as well as in the absence of rotation. In the nonrotating case these flows are, however, always only kinematic, not nonlinear dynamos. Nonlinearly the back-reaction of the magnetic field then forces the solution into the basin of attraction of a roll pattern incapable of dynamo action. But with rotation added parameter regions are found where the Coriolis force counteracts the Lorentz force in such a way that the asymmetric squares are also nonlinear dynamos.},
  language  = {en}
}
@article{Seehafer1998,
  author    = {Seehafer, Norbert},
  title     = {Filaments and the solar dynamo},
  isbn      = {1-88673-370-8},
  year      = {1998},
  language  = {en}
}
@article{FeudelSeehaferSchmidtmann1995,
  author    = {Feudel, Fred and Seehafer, Norbert and Schmidtmann, Olaf},
  title     = {Fluid helicity and dynamo bifurcations},
  year      = {1995},
  language  = {en}
}
@article{SeehaferDemircanFeudel2001,
  author    = {Seehafer, Norbert and Demircan, Ayhan and Feudel, Fred},
  title     = {Fluid helicity and dynamo effect},
  year      = {2001},
  abstract  = {Using the incompressible magnetohydrodynamic equations, we have numerically studied the dynamo effect in electrically conducting fluids. The necessary energy input into the system was modeled either by an explicit forcing term in the Navier-Stokes equation or fully selfconsistently by thermal convection in a fluid layer heated from below. If the fluid motion is capable of dynamo action, the dynamo effect appears in the form of a phase transition or bifurcation at some critical strength of the forcing. Both the dynamo bifurcation and subsequent bifurcations that occur when the strength of the forcing is further raised were studied, including the transition to chaotic states. Special attention was paid to the helicity of the flow as well as to the symmetries of the system and symmetry breaking in the bifurcations. The magnetic field tends to be accumulated in special regions of the flow, notably in the vicinity of stagnation points or near the boundaries of convection cells.},
  language  = {en}
}
@article{SeehaferFuhrmannValorietal.2007,
  author    = {Seehafer, Norbert and Fuhrmann, M. and Valori, Gherardo and Kliem, Bernhard},
  title     = {Force-free magnetic fields in the solar atmosphere},
  year      = {2007},
  language  = {en}
}
@article{HassaninKliemSeehafer2016,
  author    = {Hassanin, Alshaimaa and Kliem, Bernhard and Seehafer, Norbert},
  title     = {Helical kink instability in the confined solar eruption on 2002 May 27},
  series = {Astronomische Nachrichten = Astronomical notes},
  volume    = {337},
  journal   = {Astronomische Nachrichten = Astronomical notes},
  publisher = {Wiley-VCH},
  address   = {Weinheim},
  issn      = {0004-6337},
  doi       = {10.1002/asna.201612446},
  pages     = {1082 -- 1089},
  year      = {2016},
  language  = {en}
}
@article{SeehaferGellertKuzanyanetal.2003,
  author    = {Seehafer, Norbert and Gellert, Marcus and Kuzanyan, Kirill M. and Pipin, V. V.},
  title     = {Helicity and the solar dynamo},
  year      = {2003},
  language  = {en}
}
@article{KliemSeehafer2022,
  author    = {Kliem, Bernhard and Seehafer, Norbert},
  title     = {Helicity shedding by flux rope ejection},
  series = {Astronomy and astrophysics : an international weekly journal},
  volume    = {659},
  journal   = {Astronomy and astrophysics : an international weekly journal},
  publisher = {EDP Sciences},
  address   = {Les Ulis},
  issn      = {0004-6361},
  doi       = {10.1051/0004-6361/202142422},
  pages     = {9},
  year      = {2022},
  abstract  = {We quantitatively address the conjecture that magnetic helicity must be shed from the Sun by eruptions launching coronal mass ejections in order to limit its accumulation in each hemisphere. By varying the ratio of guide and strapping field and the flux rope twist in a parametric simulation study of flux rope ejection from approximately marginally stable force-free equilibria, different ratios of self- and mutual helicity are set and the onset of the torus or helical kink instability is obtained. The helicity shed is found to vary over a broad range from a minor to a major part of the initial helicity, with self helicity being largely or completely shed and mutual helicity, which makes up the larger part of the initial helicity, being shed only partly. Torus-unstable configurations with subcritical twist and without a guide field shed up to about two-thirds of the initial helicity, while a highly twisted, kink-unstable configuration sheds only about one-quarter. The parametric study also yields stable force-free flux rope equilibria up to a total flux-normalized helicity of 0.25, with a ratio of self- to total helicity of 0.32 and a ratio of flux rope to external poloidal flux of 0.94. These results numerically demonstrate the conjecture of helicity shedding by coronal mass ejections and provide a first account of its parametric dependence. Both self- and mutual helicity are shed significantly; this reduces the total initial helicity by a fraction of ∼0.4--0.65 for typical source region parameters.},
  language  = {en}
}