Diffusion and synchronization in an ion-trap resonator
| Autor: | Daniel Zajfman, B. Amarant, Henrik B. Pedersen, Oded Heber, M. L. Rappaport, Daniel Strasser |
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| Rok vydání: | 2002 |
| Předmět: | |
| Zdroj: | Physical Review A. 65 |
| ISSN: | 1094-1622 1050-2947 |
| DOI: | 10.1103/physreva.65.042704 |
| Popis: | Ion traps are able to trap charged particles for a long time, and they have been successfully applied in several areas of physics @1#. Among the many applications of ion traps is their use for atomic and molecular physics, such as for the study of metastable states @2#, and cluster cooling @3#. The dynamics of trapped ions has drawn much attention since the early days of ion trapping @ 4‐7 #. One item of interest in these systems stems from collective effects which can be studied both in the laboratory under well defined conditions and with developed theoretical methods. Recently, a different class of ion traps has been developed @ 8‐1 2#, in which ions oscillate between a pair of electrostatic mirrors, much like photons in an optical resonator. The trapped ions have kinetic energies of a few keV in the central part of the trap while inside the mirrors they have only a few meV near their turning points, where they are also subject to radial focusing forces. Thus, the density of ions changes strongly within the trap, due both to their slowing down inside the mirrors and to the radial focusing. This density can increase by two to three orders of magnitude inside the mirrors as compared to its value in the field-free region of the trap. In a previous publication @13#, we have investigated the stability criteria and ion loss mechanisms for ion beams stored in such a trap. Two regions of stability were experimentally identified, and these were found by both numerical simulation and optical models to be distinct modes with very different dynamical properties. Recently, we have also demonstrated @14# that the trapped ions can synchronize their motion under certain conditions. This effect was identified by observing that the size of a packet of ions remained constant for a practically unlimited time, i.e., the debunching that is usually observed did not occur. The synchronization effect was attributed to the repulsive Coulomb interaction between the ions @14#. In this paper, we provide experimental evidence for the dynamics of both diffusion and synchronization in our electrostatic trap by experimentally investigating a particular set of trap configurations. We numerically study two onedimensional model systems, which illustrate the dynamics of diffusion and synchronization. Finally, we describe in more detail the dynamical basis of diffusion and synchronization and compare the results to numerical trajectory calculations. We find that the repulsive Coulomb interaction between the ions, in combination with the kinematical properties dictated by the electrostatic fields, can either enhance the diffusion, and hence speed up the transition to a steady state beam, or induce so strong a correlation between the ions that ion motion synchronization and self-ordering phenomena emerge. |
| Databáze: | OpenAIRE |
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