Study on the Space Charge Distribution by Using a Pulsed Laser

脉冲激光空间电荷分布研究

• 批准号: 61550018
• 负责人: AITA Osamu
• 金额: $ 1.34万
• 依托单位: College of Engineering, University of Osaka Prefecture
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1986
• 资助国家: 日本
• 起止时间: 1986 至 1987
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-61550018/
• 关键词: Pulsed Laser; Space Charge; Exoelectron; KCl:Tl; Surface Potential; TSEE; OSEE; KCl:Tl

1. The main object of this project is to study the mechanism of the exoelectron emission and the relation between this mechanism and the space charge caused under the irradiation of a pulsed laser.2. The pulsed laser system was constructed and connected to the high-vacuum apparatus for the present purpose.3. The energy spectra of optically stimulated exoelectrons were studied together with the surface potential in a KCl:Tl crystal, which recently attracts much interests in the application of this material to the solid state laser. It was found that the exoelectrons are accelerated by the internal electric field due to the space charge in their transport process to the surface and also they are affected by the non-uniform spread fo the surface potential at their escape stage. Moreover, it was found that a direct photoionization from F centers dominates the mechanism of the optically stimulated exoelectron emission and also the two-step model involving the photo-ionization and thermal-ionization from F centers should be modified to interpret the present experimental results.4. The Monte Carlo calculation of the energy spectra of thermally stimulated exoelectrons indicates that the space charge distributes within several hundreds of angstrom from the surface in an X-irradiated KCl:Tl crystal, and thus, its range is less than the limitation of the present experimental apparatus. Further improvements are desired in order to see the relation between the space charge distribution and the exoelectron emission by using the pulsed laser.

1.本课题的主要目的是研究脉冲激光照射下的外电子发射机制及其与空间电荷的关系。构建了脉冲激光系统，并将其与高真空装置相连。本文研究了KCl：Tl晶体中光受激外电子的能谱和表面电势，这种材料在固体激光器中的应用引起了人们的兴趣。结果表明，外电子在输运到表面的过程中，由于空间电荷的作用，受到内部电场的加速作用，并且在逃逸阶段受到表面电势的不均匀扩散的影响。此外，还发现F中心的直接光致电离是产生光激励外电子发射的主要机制，考虑F中心的光致电离和热电离的两步模型也需要修正以解释目前的实验结果。用蒙特卡罗方法计算了受X射线辐照的KCl：Tl晶体中热受激外电子的能谱，结果表明，空间电荷分布在距晶体表面几百埃的范围内，其范围小于现有实验装置的限制。为了研究脉冲激光的空间电荷分布与外电子发射之间的关系，还需要进一步的改进。

项目成果

Masao Kamada: physica status solidi(a). 94. 275-282 (1986)

Masao Kamada：物理状态固体（a）。

Masao Kamada: "Energy Spectra of Thermally Stimulated Exoelectrons from NaCl and NaCl:Cu X-Irradiated at 77K" Physica status solidi (a). 94. 275-282 (1986)

Masao Kamada：“77K 下 NaCl 和 NaCl:Cu X 辐照的热刺激外电子的能谱”物理状态固体 (a)。