  We consider a single Cooper pair transistor (SCPT) coupled capacitively to a
voltage biased Josephson junction, used as a high frequency generator. Thanks
to the high energy of photons generated by the Josephson junction, transitions
between energy levels, not limited to the first two levels, were induced and
the effect of this irradiation on the DC Josephson current of the SCPT was
measured. This allows to probe the phase and gate bias dependence of energy
levels of the SCPT at high energy. Because the energies of photons can be
higher than the superconducting gap we can induce not only transfer of Cooper
pairs but also transfer of quasi-particles through the island of the SCPT, thus
controlling the poisoning of the SCPT. We show that this can both decrease and
increase the average Josephson energy of the SCPT : its supercurrent is then
controlled by high-frequency
