  The role of the ILC final focus system (FFS) is to demagnify the beam to the
sizes at the IP required to meet the ILC luminosity goals. The current design
of final focus performs perfect chromaticity correction in both horizontal and
vertical planes. Based on this design a set of alternative optical
configurations were studied in which the horizontal beam size at the IP is
increased while at the same time the vertical one is decreased, with the goal
of reducing beamsstrahlung emission. Luminosity reduction due to the hour glass
effect must be considered because betay*/sigmaz* becomes much smaller in this
case. The beam-beam interaction simulation by Guineapig++ was used for
evaluation. Reduced bunch lengths are used to make sure that the obtained
luminosities are not lower than those of the ILC original (nominal)
configuration.
