  The photoionisation of rubidium in strong infra-red laser fields based on ab
initio calculations was investigated. The bound and the continuum states are
described with Slater orbitals and Coulomb wave packets, respectively. The
bound state spectra were calculated with the variational method and we found it
reproduced the experimental data within a few percent accuracy. Using the
similar approach, ionisation of Rb was also successfully investigated. The
effects of the shape and the parameters of the pulse to the photoionisation
probabilities and the energy spectrum of the ionised electron are shown. These
calculations may provide a valuable contribution at the design of laser and
plasma based novel accelerators, the CERN AWAKE experiment.
