Size of the current steps in microwave irradiation of Josephson junctions

The size of current steps during the microwave irradiation of Josephson junctions is calculated within the framework of the tunnel theory for small values of beta. Positions of the end points are plotted for the first three steps and for the critical current as a function of the amplitude of the external microwave field for a symmetric tunnel junction at T = 0; frequency dependence on the maximum size which could be obtained for the first step by varying the amplitude of the external microwave field is also shown. Results are compared with those of other models.