Reversible and irreversible emittance growth

Emittance growth in bunched charged particle beams in linear accelerators is considered in the case of a Hamiltonian system where nonlinear and time-dependent forces are dominant. Emittance growth is divided into two classes: reversible and irreversible depending on the corresponding entropy change. We consider the case where the measurement resolution is important. We show that a generalized free-energy function acts as a driver for phase-space evolution and emittance growth.