Arcus is a concept for a National Aeronautics and Space Administration probe-class X-ray mission to deliver high-resolution Far Ultraviolet and X-ray spectroscopy with two separate instruments. We focus on the X-ray spectrograph (XRS). It consists of four spectral channels arranged in a double-tilted Rowland torus geometry. It combines cost-effective silicon pore optics with high-throughput critical-angle transmission gratings to achieve at least R>3000 in a bandpass from 12 to 50 Å. We present ray-tracing studies to derive performance characteristics such as the spectral resolving power and effective area and look at the best positioning of the four channels to improve the resiliency toward misalignments and reduce the overall impact of chip gaps. We study the effect of misalignments on the performance and present alignment requirements in 6 degrees of freedom for all optical elements in the XRS. We conclude that most tolerances can be achieved with mechanical means alone.

中文翻译：

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Arcus X 射线望远镜性能预测和对准要求


Arcus 是美国国家航空航天局探测器级 X 射线任务的一个概念，旨在通过两台独立的仪器提供高分辨率的远紫外和 X 射线光谱。我们专注于 X 射线光谱仪 （XRS）。它由四个光谱通道组成，排列在双倾斜的罗兰圆环几何结构中。它将经济高效的硅孔光学元件与高通量临界角透射光栅相结合，在 12 至 50 Å 的带通中实现至少 R>3000。我们提出了光线追踪研究，以得出光谱分辨能力和有效面积等性能特征，并研究四个通道的最佳定位，以提高对错位的弹性并减少芯片间隙的整体影响。我们研究了错位对性能的影响，并提出了 XRS 中所有光学元件在 6 个自由度上的对准要求。我们得出的结论是，大多数公差可以仅通过机械方式实现。