A laser ion source coupled with a radio frequency quadrupole linac accelerator is being proposed as a suitable system for the production of a low energy, high-current stable lithium beam. In order to maximize the lithium yield, plasmas generated by laser ablation of different materials based on lithium (Li, LiOH, and LiNbO3) have been characterized by using a Faraday cup and an electrostatic ion analyzer in the time of flight configuration. A wide range of laser power density has been investigated (109-1012 W/cm2) using two Nd:YAG lasers operating at different wavelengths (1064 nm and 532 nm), pulse durations (6 ns and 17 ns), and maximum energies (1400 mJ and 210 mJ). This paper outlines the pros and cons of the investigated materials by studying how the ion energy, yields, and charge state distributions are modified when the laser power density is changed. Considerable attention has been paid to the higher charge states of oxygen, which may occur with the same mass-to-charge ratio of Li3+. The analysis has evidenced that LiNbO3 represents a valid target since it allows minimizing the O6+/7Li3+ ratio down to 2.5% by using a laser power density of 1.8 × 1010 W/cm2. For such a condition, a Li3+ current of 1.4 mA/cm2 has been measured.

中文翻译：

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用于生产稳定锂束的激光靶参数优化

与射频四极杆直线加速器耦合的激光离子源被提议作为用于产生低能量、高电流稳定锂束的合适系统。为了最大限度地提高锂产量，通过在飞行时间配置中使用法拉第杯和静电离子分析仪，对基于锂的不同材料（Li、LiOH 和 LiNbO3）进行激光烧蚀产生的等离子体进行了表征。使用两个工作在不同波长（1064 nm 和 532 nm）、脉冲持续时间（6 ns 和 17 ns）和最大能量（ 1400 毫焦和 210 毫焦）。本文通过研究离子能量、产率、当激光功率密度改变时，电荷状态分布会发生变化。氧的较高电荷态引起了相当多的关注，这可能发生在 Li3+ 的质荷比相同的情况下。分析表明，LiNbO3 代表了一个有效的目标，因为它允许通过使用 1.8 × 1010 W/cm2 的激光功率密度将 O6+/7Li3+ 比率最小化至 2.5%。对于这种情况，测得的 Li3+ 电流为 1.4 mA/cm2。