General formulas for adiabatic invariants in nearly periodic Hamiltonian systems

@article{Burby2020GeneralFF,
  title={General formulas for adiabatic invariants in nearly periodic Hamiltonian systems},
  author={Joshua William Burby and Jonathan Squire},
  journal={Journal of Plasma Physics},
  year={2020},
  volume={86}
}
While it is well known that every nearly periodic Hamiltonian system possesses an adiabatic invariant, extant methods for computing terms in the adiabatic invariant series are inefficient. The most popular method involves the heavy intermediate calculation of a non-unique near-identity coordinate transformation, even though the adiabatic invariant itself is a uniquely defined scalar. A less well-known method, developed by S. Omohundro, avoids calculating intermediate sequences of coordinate… 

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