30 keV H+在聚碳酸酯微孔膜中动态输运过程的实验和理论研究

测量了30 keV的H⁺入射倾斜角度为-1°和-2°的聚碳酸酯微孔膜后，出射粒子二维分布图、角度分布、相对穿透率以及出射H⁺电荷态纯度随沉积电荷的演化.实验中30 keV的H⁺在微孔膜中输运特性与之前其他能区离子在微孔膜中输运特性有显著不同，实验中直接观测到出射粒子导向部分和散射部分的动态演化过程，出射的H⁺由沿微孔孔轴方向的导向H⁺和沿入射束流方向的散射H⁺两部分组成，随着微孔内电荷斑的沉积，出射的导向H⁺的占比不断减小，出射散射H⁺占比不断增加；出射H⁰占总出射粒子的比例不断减小，其中心方向逐步向入射束流方向偏转.微孔膜处于不同倾斜角度时，微孔内沉积电荷斑的位置和电场强度是不同的.同时模拟计算了入射H⁺在微孔内部的运动轨迹、微孔内部电荷斑电势和场强分布，实验结果和理论结果得到了很好的验证.对出射离子导向部分和散射部分的动态演化过程的观测和理论解释，使得对中能区离子在微孔膜中输运机制有更好的认识.

Experimental and theoritical research on the dynamical transmission of 30 keV H+ ions through polycarbonate nanocapillaries

The ions with different incident energies transmitting through insulating nanocapillaries are studied in various configurations. For the low energy ions transmitting through nanocapillaries, Stolterfoht et al.2002 Phys. Rev. Lett. 88 133201] have observed the guiding effect. Subsequent studies revealed that the self-organizing charge patches on the capillary wall inhibit charge exchange and the ions are transmitted along the capillary axis direction. The high energies of ions transmitting through nanocapillaries are measured, the main transmission mechanism is multiple random inelastic collisions below the surface, and the charge patches will not affect the transmitted ions trajectories. The transmission features of the intermediate energy ions are different from those of the low and high energy ions. The ion beams with intermediate energies have many applications, so it is necessary to understand the transmission features of the intermediate energy ions though nanocapillaries. Recent studies have focused on the transmission of the intermediate energies ions through the nanocapillaries. In the present work, we investigate thie transmission features, such as the two-dimensional transmitted angular distributions, the charge states and position distributions, and the evolution of the relative transmission rate and the charge purity of 30 keV H⁺ transmitting through nanocapillaries in a polycarbonate membrane at the angles of-1° and-2°. The experimental data clearly show that the transmitted H⁺ ions consist of the transmitted scattering H⁺ ions, which are located around the direction of the incident beam, and the transmitted guiding H⁺ ions, which are located around the direction of the capillary axis. With the charges depositing in the capillary, the proportion of the transmitted scattering H⁺ ions increases and the proportion of the transmitted guiding H⁺ ion decreases, which directly demonstrates the dynamical evolution of the scattering ions and the guiding ions. To understand the competition between the transmitted scattering ions and the transmitted guiding ions and the physical picture of the intermediate energy ions transmitting through the insulating nanocapillaries, the trajectories of the H⁺ ions in the capillary and the potential distribution and electric field intensity distribution in the capillary are numerically simulated. The results show that the potential distributions and electric field intensitiesy are different for H⁺ ions transmitting through nanocapillaries at various tilt angles, and the simulation results are in good agreement with the experimental data. The experimental and simulation results give us a further insight into the mechanisms of guiding and scattering in intermediate energy ions transmitting through nanocapillaries.