Creation of sine-Gordon solitons by a pulse force

We study the problem of soliton generation by an external pulse force in the framework of the sine-Gordon system. The problem is applied to the creation of fluxons in long Josephson junctions or magnetic solitons in one-dimensional magnetic systems with an easy-plane anisotropy. In case of a small duration of driving pulse T, we find the connection between parameters of the pulse force and the wave field created after the pulse. To define the parameters of the generated soliton we use an approach based on the inverse scattering transform. The analytical results are presented in two cases when the spatial length L of the pulse is either much larger or much smaller than the value ${\mathit{V}}_{\mathit{g}}$T, ${\mathit{V}}_{\mathit{g}}$ being the maximum value of the group velocity in the system. The threshold conditions admitting generation of either breathers or kink-antikink pairs are found. Numerical simulations are performed for arbitrary values of the ratio L/${\mathit{V}}_{\mathit{g}}$T but for small T. In two limiting cases the results are in good comparison with the obtained analytical formulas. The influence of dissipative losses on the soliton creation is also studied by analytical and numerical methods. It is demonstrated that dissipation leads to an increasing of the threshold conditions to generate solitons by the pulse force.