  Several, recently proposed methods of surface manufacturing based on ion beam
sputtering, which involve dual beam setups, sequential application of ion beams
from different directions, or sample rotation, are studied with the method of
kinetic Monte Carlo simulation of ion beam erosion and surface diffusion. In
this work, we only consider erosion dominated situations. The results are
discussed by comparing them to a number of theoretical propositions and to
experimental findings. Two ion-beams aligned opposite to each other produce
stationary, symmetric ripples. Two ion beams crossing at right angle will
produce square patterns only, if they are exactly balanced. In all other cases
of crossed beams, ripple patterns are created, and their orientations are shown
to be predictable from linear continuum theory. In sequential ion beam
sputtering we find a very rapid destruction of structures created from the
previous beam direction after a rotation step, which leads to a transient
decrease of overall roughness. Superpositions of patterns from several rotation
steps are difficult to obtain, as they exist only in very short time windows.
In setups with a single beam directed towards a rotating sample, we find a
non-monotonic dependence of roughness on rotation frequency, with a very
pronounced minimum appearing at the frequency scale set by the relaxation of
prestructures observed in sequential ion beam setups. Furthermore we find that
the logarithm of the height of structures decreases proportional to the inverse
frequency.
