ИСТИНА

An interesting feature of ultracold plasmas are multiple subharmonics of the electron emission caused by a microwave irradiation. Here, we suggest a model of this phenomenon, based on the ionization of secondary Rydberg atoms formed in the expanding plasma bunches. As follows from our numerical simulations, such ionization really occurs at a series of the preferable frequencies. Besides, it is irrelevant to the boundary conditions and possesses a correct dependence of the electron temperature.