title: First-harmonic approximation in nonlinear chirped-driven oscillators.
abstract: Nonlinear classical oscillators can be excited to high energies by a weak driving field provided the drive frequency is properly chirped. This process is known as autoresonance (AR). We find that for a large class of oscillators, it is sufficient to consider only the first harmonic of the motion when studying AR, even when the dynamics is highly nonlinear. The first harmonic approximation is also used to relate AR in an asymmetric potential to AR in a "frequency equivalent" symmetric potential and to study the autoresonance breakdown phenomenon.
authors.affiliation: Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel.
authors.forename: Raam
authors.initials: R
authors.lastname: Uzdin
authors.affiliation: Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel.
authors.forename: Lazar
authors.initials: L
authors.lastname: Friedland
authors.affiliation: Racah Institute of Physics, Hebrew University, Jerusalem 91904, Israel.
authors.forename: Omri
authors.initials: O
authors.lastname: Gat