Vassholz Malte, Salditt Tim
Institut für Röntgenphysik, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, Göttingen, Germany.
Sci Adv. 2021 Jan 22;7(4). doi: 10.1126/sciadv.abd5677. Print 2021 Jan.
We demonstrate x-ray generation based on direct emission of spontaneous x-rays into waveguide modes. Photons are generated by electron impact onto a structured anode target, which is formed as an x-ray waveguide or waveguide array. Both emission of characteristic radiation and bremsstrahlung are affected by the changes in mode density induced by the waveguide structure. We investigate how the excited modal pattern depends on the positions of the metal atoms and the distance of the focused electron beam with respect to the waveguide exit side. We compare the results to synchrotron-excited fluorescence. We then discuss how x-ray generation in waveguides can be used to increase the brilliance and directional emission of tabletop x-ray sources, with a corresponding increase in the spatial coherence. On the basis of the Purcell effect, we lastly show that the gain of emission into waveguide modes is governed by the quality factor of the waveguide.
我们展示了基于自发X射线直接发射到波导模式中的X射线产生。光子是通过电子撞击结构化阳极靶产生的，该靶被形成为X射线波导或波导阵列。特征辐射和轫致辐射的发射都受到波导结构引起的模式密度变化的影响。我们研究了激发的模态图案如何取决于金属原子的位置以及聚焦电子束相对于波导出口侧的距离。我们将结果与同步加速器激发的荧光进行比较。然后，我们讨论了波导中的X射线产生如何用于提高桌面X射线源的亮度和定向发射，并相应地提高空间相干性。基于珀塞尔效应，我们最后表明，进入波导模式的发射增益由波导的品质因数决定。
