On the Dirichlet Problem of Mixed Type for Lower Hybrid Waves in Axisymmetric Cold Plasmas

• Published in: Archive for rational mechanics and analysis Vol. 217; no. 1; pp. 37 - 69
• Main Authors: Lupo, Daniela, Monticelli, Dario D., Payne, Kevin R.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.07.2015; Springer Nature B.V
• Subjects: Axisymmetric; Classical Mechanics; Cold plasmas; Complex Systems; Dirichlet problem; Fluid- and Aerodynamics; Functionals; Mathematical and Computational Physics; Mathematical models; Nonlinearity; Partial differential equations; Physics; Physics and Astronomy; Subspaces; Theoretical; Dirichlet Problem; Lower Order Term; Weak Solution; Weighted Sobolev Space; Unique Weak Solution
• ISSN: 0003-9527; 1432-0673
• DOI: 10.1007/s00205-014-0828-8

For a class of linear second order partial differential equations of mixed elliptic-hyperbolic type, which includes a well known model for analyzing possible heating in axisymmetric cold plasmas, we give results on the weak well-posedness of the Dirichlet problem and show that such solutions are characterized by a variational principle. The weak solutions are shown to be saddle points of natural functionals suggested by the divergence form of the PDEs. Moreover, the natural domains of the functionals are the weighted Sobolev spaces to which the solutions belong. In addition, all critical levels will be characterized in terms of global extrema of the functionals restricted to suitable infinite dimensional linear subspaces. These subspaces are defined in terms of a robust spectral theory with weights which is associated to the linear operator and is developed herein. Similar characterizations for the weighted eigenvalue problem and nonlinear variants will also be given. Finally, topological methods are employed to obtain existence results for nonlinear problems including perturbations in the gradient which are then applied to the well-posedness of the linear problem with lower order terms.