Picosecond time-resolved X-ray holography

皮秒时间分辨X射线全息术

基本信息

批准号：
13480142
负责人：
UESAKA Mitsuru
金额：
$ 9.66万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

We faced a problem of insufficiency of laser plasma X-ray intensity at the start of this study for X-ray holography. Then, making a change in our plan, we aimed time-resolved imaging of a laser ablation process with 10 ps time resolution and tried to take X-ray absorption images of metallic materials and organic materials. It was found possible that sufficient image contrast would be achievable in 10 shots for metallic samples and 100 shots for organic materials. Thus, X-ray enhancement to the extent of 10 〜 100 times was necessary in order to make a single-shot imaging. The yield of the laser plasma X-ray is strongly dependent on the pre-plasma distribution. We investigated the condition of the pre-plasma with numerical simulations and found that the amount of X-rays would be increased 10 times by suppression of the pre-plasma expansion. Several experiments were carried out to improve the laser contrast. Those methods, however, were not applied to actual an X-ray generation experiment at this time. The number of photons of CuKa generated from a laser plasma was estimated experimentally as 4.4 x 10^9 [photons/shot/4 π sr]. Laser contrast was improved about one order ( ASE intensity 〜 10^12 W/cm^2). The efforts to improve the laser contrast such as phase transition in a semiconductor crystal, relativistic self-focus in a gas-jet, and metal-coated targets are continued. X-ray yield is going to increase more than ten times by pre-pulse control. We expect further increase of X-rays because of the laser upgrade to be done in the near future.

在本研究开始时，我们面临激光等离子体X射线强度不足的问题。然后，改变计划，我们针对具有10 ps时间分辨率的激光消融过程的时间分辨成像，并试图拍摄金属材料和有机材料的X射线抽象图像。人们发现，有可能在10张金属样品和有机材料的100张照片中成功进行足够的图像对比度。为了制作单次成像，需要增强X射线的范围10至100倍。激光等离子体X射线的产率在很大程度上取决于血浆前分布。我们通过数值模拟调查了前等离子膜的状况，发现X射线的量通过抑制X射线的量增加了10倍。进行了几项实验以改善激光对比度。但是，这些方法目前尚未应用于实际的X射线生成实验。实验估计从激光等离子体产生的CUKA照片的数量为4.4 x 10^9 [光子/shot/4πsr]。激光对比度大约改善了一个阶（ASE强度〜10^12 w/cm^2）。努力改善激光对比度，例如在半导体晶体中的相变，气流中的相对论自聚焦和金属涂层靶标。 X射线产量将通过脉冲前控制增加十倍以上。我们预计，由于激光升级在不久的将来会进一步增加。