Theory of Coherent Radiation from Periodic Structures

在现代科学中，强X光子源如GeV同步辐射装置的作用是相当重要的。毫无疑问，更紧凑、可调谐、单色以及强X光子源将在科学、技术和医学的各个领域带来进一步的发展。在这方面，我们必须在已知的相干辐射（如沟道辐射、参量x辐射等）之外，寻找一种新的相干辐射机制。我们试图找到一种新的相干辐射机制，并解释这一领域的实验结果。以下是我们在这个问题上的主要结果.预测了MeV平面沟道电子的一种新型强X光子发射。它被发射到相对于电子束接近布拉格角的方向。预测的X光子的谱密度比参量X辐射的谱密度大几百倍.本文给出了最近观测到的层状硅单晶单色x射线辐射的理论。数值计算结果与实验数据吻合较好。理论是基于衍射跃迁辐射的量子力学方法.对沟道电子的非相干韧致辐射进行了计算机模拟。我们的结果与1.04GeV光子从1.3GeV沟道电子到Si晶体的角度依赖性的实验结果一致，而这一点至今还没有得到理论上的解释。

In the modern science the role of strong x-photon sources such as the GeV synchrotron radiation facilities is quite important. There is no doubt that a more compact, tunable, monochromatic as well as strong x-photon source will bring a further developments in a varaety of fields of science, technology, and medicine. In this connection, we have to investigate a new mechanism for such sources beyond the known coherent radiations such as channeling radiation, parametric x radiation, etc, We are trying to find a new mechanism of coherent radiation as well as explaining experimental results in this field. Followings are our main results related on this problem.1. A new type of strong X-photon emission is predicted for MeV planar channeled electrons. It is emitted into the direction close to the Bragg angle with respect to the electron beam. The spectral density of the predicted X-photons is more than hundreds times larger than that of parametric x radiation.2. Theory of monochromatic x radiation from stratified Si single crystal observed recently has been given. Our numerical results agree with the experimental data. Theory is based on the quantum-mechanical approach to the diffracted transition radiation.3. Computer simulation on the incoherent bremsstrahlung from channeled electrons has been per-formed. Our result agrees well with the experimental result of the angular dependence of 1.04GeV photons from 1.3GeV channeled electrons electrons in Si crystals that has not been explained theoretically so far.