Tunable coherent radiation in the soft X-ray and extreme ultraviolet spectral regions
Tunable coherent radiation in the soft X-ray and extreme ultraviolet spectral regions
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软 X 射线和极紫外光谱区域的可调谐相干辐射
DOI：
10.1109/3.760317
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发表时间：
1999
影响因子：
2.5
通讯作者：
J. Underwood
中科院分区：
文献类型：
--
作者：
D. Attwood;P. Naulleau;K. Goldberg;E. Tejnil;Chang Chang;R. Beguiristain;P. Batson;J. Bokor;E. Gullikson;M. Koike;H. Medecki;J. Underwood
由相对论电子穿过周期性磁体结构产生的波动器辐射可以在电磁波谱的极紫外（EUV）、软X射线（SXR）和X射线区域中提供非常明亮和部分相干的辐射的连续可调谐源。通常，在1/N相对频谱带宽内辐射1-10 W，其中N是100阶。单色器经常被用来缩小光谱带宽和增加纵向相干长度，尽管有超过比例的功率损失。采用针孔空间滤波来提供由波长、电子束和波荡器参数确定的功率水平的空间相干辐射。在本文中，实验中广泛可调，空间相干功率产生在EUV和软X射线波长从约3至16 nm（80-430-eV光子能量）。在相对光谱带宽为9/spl × 10/sup-4/时，1.90GeV电子穿过周期为8 cm的55周期波荡器，获得了10 /spl μ/W量级的空间相干功率.该辐射已被用于13.4 nm干涉仪测试，实现了均方根波前误差（偏离球面度）为/spl λ//sub euv//330。这些技术的规模在一个简单的方式，以较短的软X射线波长使用4-5厘米周期波动在1.90 GeV和X射线波长的顺序为0.1纳米使用更高的能量（6-8 GeV）的电子束在其他设施。
Undulator radiation, generated by relativistic electrons traversing a periodic magnet structure, can provide a continuously tunable source of very bright and partially coherent radiation in the extreme ultraviolet (EUV), soft X-ray (SXR), and X-ray regions of the electromagnetic spectrum. Typically, 1-10 W are radiated within a 1/N relative spectral bandwidth, where N is of order 100. Monochromators are frequently used to narrow the spectral bandwidth and increase the longitudinal coherence length, albeit with a more than proportionate loss of power. Pinhole spatial filtering is employed to provide spatially coherent radiation at a power level determined by the wavelength, electron beam, and undulator parameters. In this paper, experiments are described in which broadly tunable, spatially coherent power is generated at EUV and soft X-ray wavelengths extending from about 3 to 16 nm (80-430-eV photon energies). Spatially coherent power of order 10 /spl mu/W is achieved in a relative spectral bandwidth of 9/spl times/10/sup -4/, with 1.90-GeV electrons traversing an 8-cm period undulator of 55 periods. This radiation has been used in 13.4-nm interferometric tests that achieve an rms wavefront error (departure from sphericity) of /spl lambda//sub euv//330. These techniques scale in a straightforward manner to shorter soft X-ray wavelengths using 4-5-cm period undulators at 1.90 GeV and to X-ray wavelengths of order 0.1 nm using higher energy (6-8 GeV) electron beams at other facilities.