| Abstract: | In this paper,we introduce a method of quantitatively evaluating and controlling the space charge effect of a lasercooled three-dimensional(3 D) ion system in a linear Paul trap.The relationship among cooling efficiency,ion quantity,and trapping strength is analyzed quantitatively,and the dynamic space distribution and temporal evolution of the 3 D ion system on a secular motion period time scale in the cooling process are obtained.The ion number influences the eigen-micromotion feature of the ion system.When trapping parameter q is ~ 0.3,relatively ideal cooling efficiency and equilibrium temperature can be obtained.The decrease of axial electrostatic potential is helpful in reducing the micromotion heating effect and the degradation in the total energy.Within a single secular motion period under different cooling conditions,ions transform from the cloud state(each ion disperses throughout the envelope of the ion system) to the liquid state(each ion is concentrated at a specific location in the ion system) and then to the crystal state(each ion is subjected to a fixed motion track).These results are conducive to long-term storage and precise control,motion effect suppression,high-efficiency cooling,and increasing the precision of spectroscopy for a 3 D ion system. |
