Theory of Relativistic Surface Plasmon Excitation on Smooth Surface by High-Intensity Laser

Fuente: arXiv
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Autores principales: Lei, Bifeng, Qiao, Bin, Zepf, Matt, Xia, Guoxing, Welsh, Carsten
Formato: Preprint
Publicado: 2026
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author Lei, Bifeng
Qiao, Bin
Zepf, Matt
Xia, Guoxing
Welsh, Carsten
author_facet Lei, Bifeng
Qiao, Bin
Zepf, Matt
Xia, Guoxing
Welsh, Carsten
contents We present a classical theory of relativistic surface plasmon (RSP) excitation at a smooth plasma-vacuum interface driven by either a ponderomotive force or an electric field of an intense laser pulse. Starting from Maxwell equations coupled to a cold-fluid plasma response, we derive a general driven wave equation for the RSP and solve it analytically. We show that an infinite planar surface enforces conservation of the in-plane wavevector. A finite longitudinal interaction length or axial modulation supplies a finite kz spectrum, while cylindrical curvature replaces one continuous transverse in-plane wavenumber by a discrete azimuthal mode index m. This partially relaxes the planar in-plane constraint, while axial phase matching remains controlled by the longitudinal spectrum of the drive. The excitation strength is controlled by the overlap between the drive and the surface eigenfield, which is determined by the surface geometry. This provides a general principle for controlling RSP excitation. We also show that relativistic effects can substantially modify the dielectric response and can be preliminarily verified by particle-in-cell simulations. Within the local relativistic dielectric model, the overlap-normalised planar source saturates at large a0, and cylindrical curvature partially alleviates this reduction before strong surface softening develops. The role of surface geometry is analysed. A cylindrical surface can sustain an on-axis accelerating field, enabling highly nonlinear wakefield generation for particle acceleration. In addition, the cylindrical geometry imposes a precise mode-selection rule that provides intrinsic control over RSP excitation. Axisymmetric ponderomotive drive selects fundamental mode m=0. A linearly polarised laser field selects a superposition of m=+1 and m=-1 modes, and a circularly polarised laser field selects a single helical mode.
format Preprint
id arxiv_https___arxiv_org_abs_2604_26705
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Theory of Relativistic Surface Plasmon Excitation on Smooth Surface by High-Intensity Laser
Lei, Bifeng
Qiao, Bin
Zepf, Matt
Xia, Guoxing
Welsh, Carsten
Plasma Physics
We present a classical theory of relativistic surface plasmon (RSP) excitation at a smooth plasma-vacuum interface driven by either a ponderomotive force or an electric field of an intense laser pulse. Starting from Maxwell equations coupled to a cold-fluid plasma response, we derive a general driven wave equation for the RSP and solve it analytically. We show that an infinite planar surface enforces conservation of the in-plane wavevector. A finite longitudinal interaction length or axial modulation supplies a finite kz spectrum, while cylindrical curvature replaces one continuous transverse in-plane wavenumber by a discrete azimuthal mode index m. This partially relaxes the planar in-plane constraint, while axial phase matching remains controlled by the longitudinal spectrum of the drive. The excitation strength is controlled by the overlap between the drive and the surface eigenfield, which is determined by the surface geometry. This provides a general principle for controlling RSP excitation. We also show that relativistic effects can substantially modify the dielectric response and can be preliminarily verified by particle-in-cell simulations. Within the local relativistic dielectric model, the overlap-normalised planar source saturates at large a0, and cylindrical curvature partially alleviates this reduction before strong surface softening develops. The role of surface geometry is analysed. A cylindrical surface can sustain an on-axis accelerating field, enabling highly nonlinear wakefield generation for particle acceleration. In addition, the cylindrical geometry imposes a precise mode-selection rule that provides intrinsic control over RSP excitation. Axisymmetric ponderomotive drive selects fundamental mode m=0. A linearly polarised laser field selects a superposition of m=+1 and m=-1 modes, and a circularly polarised laser field selects a single helical mode.
title Theory of Relativistic Surface Plasmon Excitation on Smooth Surface by High-Intensity Laser
topic Plasma Physics
url https://arxiv.org/abs/2604.26705