Explosive Parametric Instability of the Free Surface of a Liquid Metal in a Radio Frequency Electric Field

The possibility of the appearance of microirregularities on the surface of a liquid metal under the action of a radio frequency electric field is investigated as applied to the conditions of the compact linear collider accelerating structures. These microirregularities are formed as a result of the development of parametric instability caused by the resonant interaction between the oscillating field and surface electrocapillary waves. It is shown that if the amplitude of the boundary oscillations becomes large enough, the dynamics of the system begins to be governed by nonlinear effects. In this case, it should be expected that the instability will become explosive and the boundary of the melt will cease to be smooth in a finite time: various kinds of singularities (cuspidal points, drops, and jets) will form. This will lead to a sharp increase in the emissive ability of the electrode surface and, as a consequence, to failure of the electric strength of the system.