铷原子磁光阱中超冷等离子体的形成和演化（英文）

Formation and evolution of ultracold plasma in a rubidium magneto-optical trap

在铷原子的磁光阱中,通过光电离冷原子方法和稠密里德堡原子的自发演化方法产生了超冷等离子体.磁光阱中冷却并囚禁了10^7个原子,温度约为500μK,之后用一束脉冲激光将冷原子电离或者激发至高里德堡态,通过调节脉冲激光的能量控制离子数量或者里德堡原子的数量.利用延迟斜坡电场或脉冲电场引出超冷等离子体中的电子,对超冷等离子体的形成和演化进行了研究,并利用库仑势阱模型对实验结果进行了解释.实验结果表明,由于来自长寿命里德堡原子的贡献,里德堡原子自发演化形成的超冷等离子体的寿命比光电离形成的超冷等离子体的寿命长.

We obtained ultracold plasma by the photoionization of laser cooled atoms,and by the spontaneous evolution of dense Rydberg atoms in a rubidium magneto-optical trap.Up to10^7Rb atoms were trapped in the magneto-optical trap at temperature down to500μK,then a pulsed dye laser ionized or excited the cold Rb atoms,and the number of ions or Rydberg atoms was varied by the power of the pulsed laser.The dynamics of ultracold plasma was investigated by extracting the electrons from plasma using a delayed ramp or pulsed electric field.The experimental results were in good agreement with the Coulomb potential well model.Due to the contribution from the long-lived Rydberg atoms,the ultracold plasma from the spontaneous evolution of dense Rydberg atoms had a longer lifetime than that from the photoionization.