Tunneling ionization of atoms and molecules induced by intense laser pulses contains the contributions of numerous quantum orbits. Identifying the contributions of these orbits is crucial for exploring the application of tunneling and for understanding various tunneling-triggered strong-field phenomena. We perform a combined experimental and theoretical study to identify the relative contributions of the quantum orbits corresponding to the electrons tunneling ionized during the adjacent rising and falling quarter cycles of the electric field of the laser pulse. In our scheme, a perturbative second-harmonic field is added to the fundamental driving field. By analyzing the relative phase dependence of the signal in the photoelectron momentum distribution, the relative contributions of these two orbits are unambiguously determined. Our results show that their relative contributions sensitively depend on the longitudinal momentum and modulate with the transverse momentum of the photoelectron, which is attributed to the interference of the electron wave packets of the long orbit. The relative contributions of these orbits resolved here are important for the application of strong-field tunneling ionization as a photoelectron spectroscopy for attosecond time-resolved measurements.
KEYWORDS: Control systems, Algorithm development, Numerical analysis, Adaptive optics, Wireless communications, Performance modeling, Chlorine, Electronics, Electronics engineering, Global system for mobile communications
Due to scarce radio bandwidth, efficient mobility management method is necessary for the PCS. This paper presents a new mobility management method for the PCS networks. It consists of three parts: cell coding scheme, location update strategy and paging strategy. The cell code scheme, which provides information about the topology of the network to mobile terminals, is the basis for the location update strategy in this paper. The location update strategy is a simplified derivative of distance-based scheme. An adaptive distance threshold is obtained by exploiting the mobile terminal’s individual call and mobility pattern. Since the location update strategy is not designed for certain mobility model such as random walk or fluid flow model, the computation of distance threshold is not only simplified but also better matches the real moving behavior of different mobile terminals. The paging strategy in this method is two-step. The moving direction vector is introduced here to optimize the paging procedure. Two-step paging will significantly reduce the signaling cost for paging. And it can be easily generalized to multi-step paging within the call setup delay constraint. A numerical analysis between mobile terminals with various moving and call patterns is provided. The mobility management method helps optimize the location update cost for all kinds of users.
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