Electron trajectory analysis for cluster HHG and elliptical polarization. We present the return energy electrons as a function of time for the central optical cycles of a 78-fs laser pulse with 803 nm central wavelength. Blue shows the atom-to-itself return energies and return fractions (proportion of electrons returning to the parent ion). Green shows the cluster-to-itself return energies and fractions (proportion of electrons returning to the cluster). The black curve shows the absolute value of the elliptically polarized electric field. Calculations were performed for ellipticities from linear (0) to circular polarization (1) in steps of 0.01.