We are developing a laser ion source to provide a high brightness multi-charged heavy ion beam as a part of the heavy ion beam probe system, which will be used to diagnose plasma potential in the Ring Trap 1 device at the University of Tokyo. As a probe beam, Nb2+ was selected, and a detailed laser irradiation condition was explored. It was found that the laser power density of 1.2 × 109 W/cm2 gives the maximum particle number of Nb2+ per laser energy from a niobium foil target. Essential ablation plasma parameters to design the laser ion source were also obtained. The expected beam current was more than 12 mA/cm2, with a pulse width of 3.1 µs at 200 mm away from the target.

中文翻译：

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用于研究实验室磁层等离子体的紧凑型重离子源的可行性研究

我们正在开发一种激光离子源，以提供高亮度多电荷重离子束，作为重离子束探针系统的一部分，该系统将用于诊断东京大学环形陷阱 1 设备中的等离子体电位。作为探测光束，选择了 Nb2+，并探索了详细的激光照射条件。发现 1.2 × 109 W/cm2 的激光功率密度给出了来自铌箔靶的每激光能量中 Nb2+ 的最大粒子数。还获得了设计激光离子源的基本消融等离子体参数。预期的束流超过 12 mA/cm2，在距目标 200 mm 处的脉冲宽度为 3.1 µs。