Stark-potential evaporative cooling of polar molecules in a novel optical-access opened electrostatic trap

• Published in: Chinese physics B Vol. 24; no. 11; pp. 196 - 205
• Main Author: 孙慧 王振霞 王琴 李兴佳 刘建平 印建平
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.11.2015
• Subjects: Computer simulation; Electric fields; Electric potential; electrostatic trap; Electrostatics; Evaporative cooling; Mathematical analysis; Mathematical models; Monte Carlo methods; Monte Carlo simulations; 光通道; 圆盘电极; 极性分子; 蒙特卡罗方法; 蒙特卡罗模拟; 蒸发冷却; 陷阱深度; 静电场
• ISSN: 1674-1056; 2058-3834; 1741-4199
• DOI: 10.1088/1674-1056/24/11/113101

We propose a novel optical-access opened electrostatic trap to study the Stark-potential evaporative cooling of polar molecules by using two charged disk electrodes with a central hole of radius r0 = 1.5 mm, and derive a set of new analytical equations to calculate the spatial distributions of the electrostatic field in the above charged-disk layout. Afterwards, we calculate the electric-field distributions of our electrostatic trap and the Stark potential for cold ND3 molecules, and analyze the dependences of both the electric field and the Stark potential on the geometric parameters of our charged-disk scheme, and find an optimal condition to form a desirable trap with the same trap depth in the x, y, and z directions. Also, we propose a desirable scheme to realize an efficient loading of cold polar molecules in the weak-field-seeking states, and investigate the dependences of the loading efficiency on both the initial forward velocity of the incident molecular beam and the loading time by Monte Carlo simulations. Our study shows that the maximal loading efficiency of our trap scheme can reach about 95%, and the corresponding temperature of the trapped cold molecules is about 28.8 inK. Finally, we study the Stark-potential evaporative cooling for cold polar molecules in our trap by the Monte Carlo method, and find that our simulated evaporative cooling results are consistent with our developed analytical model based on trapping-potential evaporative cooling.