A moving boundary problem motivated by electric breakdown: I. Spectrum of linear perturbations

Abstract

An interfacial approximation of the streamer stage in the evolution of sparks and lightning can be written as a Laplacian growth model regularized by a `kinetic undercooling' boundary condition. We study the linear stability of uniformly translating circles that solve the problem in two dimensions. In a space of smooth perturbations of the circular shape, the stability operator is found to have a pure point spectrum. Except for the zero eigenvalue for infinitesimal translations, all eigenvalues are shown to have negative real part. Therefore perturbations decay exponentially in time. We calculate the spectrum through a combination of asymptotic and series evaluation. In the limit of vanishing regularization parameter, all eigenvalues are found to approach zero in a singular fashion, and this asymptotic behavior is worked out in detail. A consideration of the eigenfunctions indicates that a strong intermediate growth may occur for generic initial perturbations. Both the linear and the nonlinear initial value problem are considered in a second paper.

37 pages, 6 figures, revised for Physica D

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Cited by in corpus (7)

• Probing photo-ionization: Experiments on positive streamers in pure gasses and mixtures
• Electron density fluctuations accelerate the branching of streamer discharges in air
• Corner and finger formation in Hele--Shaw flow with kinetic undercooling regularisation
• Saffman-Taylor fingers with kinetic undercooling
• A moving boundary model motivated by electric breakdown: II. Initial value problem
• The onset of tree-like patterns in negative streamers
• Moving boundary approximation for curved streamer ionization fronts: Numerical tests