Generation of Broadband Tunable Coherent X-rays by Using Optical Field Induced Ionization

利用光场诱导电离产生宽带可调谐相干 X 射线

基本信息

批准号：
09450033
负责人：
SASAKI Wataru
金额：
$ 5.82万
依托单位：
Miyazaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

We have demonstrated vacuum ultraviolet emissions from pulsed rare gas jet excited by a high intensity ultrashort pulse laser. Various emission characteristics are investigated thoroughly. Ultrashort pulse Lasers are also used to control the dissociation process of alkali halide molecules in a femtosecond time scale. These knowledge should be used to develop a practical coherent x-ray source in the laboratory scale.As a result of the interaction of Ar and high intensity laser field, we have observed emissions from Ar_2^* at 126 nm for the first time together with some signals of high order harmonics. The focused laser intensity dependence of the Ar excimer intensity agrees well with that predicted by a tunnel ionization theory so called ADK theory. We, therefore, found out that the production of Ar excimers was initiated by high intensity laser produced electrons, which may become a substitution to those produced by an electron beam device.Experimental data show no difference in terms of the Ar excimer emission when linearly polarized and circularly polarized laser beams interacted with Ar. Considering about the energy transport of electrons in a high intensity laser produced plasma theoretically, we have found out a rapid conductive cooling of a plasma plays an important role for the excimer pioduction.The control of a molecule by using a high intensity laser has been demonstrated in the femtosecond time region as well. Alkali halide molecules have been excited and deexcited by using two different wavelength (ultraviolet and visible) lasers, which leads to the coherent control of the molecule with the minimum thermal effect This type of coherent molecular control means that the molecule can become a good optical amplifier even in a very short wavelength range, and can become a new coherent x-ray source.

我们已经证明了由高强度超短脉冲激光激发的脉冲稀有气体射流产生的真空紫外线发射。彻底研究了各种发射特性。超短脉冲激光器还用于在飞秒时间尺度内控制碱金属卤化物分子的解离过程。这些知识应该用于在实验室规模上开发实用的相干X射线源。由于Ar和高强度激光场相互作用，我们首次观察到Ar_2^*在126 nm处的发射一些高次谐波信号。 Ar 准分子强度的聚焦激光强度依赖性与隧道电离理论（即 ADK 理论）所预测的非常一致。因此，我们发现Ar准分子的产生是由高强度激光产生的电子引发的，这可能成为电子束装置产生的电子的替代品。实验数据表明，当线偏振时，Ar准分子的发射没有差异。圆偏振激光束与Ar相互作用。从理论上考虑高强度激光产生等离子体中电子的能量传输，我们发现等离子体的快速传导冷却对于准分子的产生起着重要作用。使用高强度激光对分子的控制已经被证明在飞秒时间区域也是如此。利用两种不同波长（紫外和可见）激光对碱卤化物分子进行激发和去激发，从而以最小的热效应对分子进行相干控制。这种相干分子控制意味着该分子可以成为良好的光放大器即使在很短的波长范围内，也可以成为一种新的相干X射线源。