Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Travelling waves and a fruitful `time' reparametrization in relativistic
  electrodynamics   We simplify the nonlinear equations of motion of charged particles in an
external electromagnetic field that is the sum of a plane travelling wave
F_t(ct-z) and a static part F_s(x,y,z): by adopting the light-like coordinate
ct-z instead of time t as an independent variable in the Action, Lagrangian and
Hamiltonian, and deriving the new Euler-Lagrange and Hamilton equations
accordingly, we make the unknown z(t) disappear from the argument of F_t. We
study and solve first the single particle equations in few significant cases of
extreme accelerations. In particular we obtain a rigorous formulation of a
Lawson-Woodward-type (no-final-acceleration) theorem and a compact derivation
of cyclotron autoresonance, beside new solutions in the presence of uniform
F_s. We then extend our method to plasmas in hydrodynamic conditions and apply
it to plane problems: the system of partial differential equations may be
partially solved and sometimes even completely reduced to a family of decoupled
systems of ordinary ones; this occurs e.g. with the impact of the travelling
wave on a vacuum-plasma interface (what may produce the slingshot effect).
Since Fourier analysis plays no role in our general framework, the method can
be applied to all kind of travelling waves, ranging from almost monochromatic
to socalled "impulses", which contain few, one or even no complete cycle.

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The categories of this paper are: patt-sol
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The categories of this paper are: mtrl-th
8
The categories of this paper are: hep-ex
1
The categories of this paper are: cs
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The categories of this paper are: cmp-lg
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The categories of this paper are: alg-geom
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The categories of this paper are: gr-qc
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: comp-gas
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The categories of this paper are: eess
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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-th