The soft X-rays (SXRs: 90–150 Å) are among the most interesting spectral ranges to be investigated in the next generation of solar missions due to their unique capability of diagnosing phenomena involving hot plasma with temperatures up to 15 MK. Multilayer (ML) coatings are crucial for developing SXR instrumentation, as so far they represent the only viable option for the development of high-efficiency mirrors in the this spectral range. However, the current standard MLs are characterized by a very narrow spectral band which is incompatible with the science requirements expected for a SXR spectrometer. Nevertheless, recent advancement in the ML technology has made the development of non-periodic stacks repeatable and reliable, enabling the manufacturing of SXR mirrors with a valuable efficiency over a large range of wavelengths. In this work, after reviewing the state-of-the-art ML coatings for the SXR range, we investigate the possibility of using M-fold and aperiodic stacks for the development of multiband SXR spectrometers. After selecting a possible choice of key spectral lines, some trade-off studies for an eight-bands spectrometer are also presented and discussed, giving an evaluation of their feasibility and potential performance.

柔软的X射线（SXRs：90–150Å）是下一代太阳能任务中最令人关注的光谱范围之一，这是因为它们具有诊断现象的独特能力，涉及温度高达15 MK的热等离子体。多层（ML）涂层对于开发SXR仪器至关重要，因为到目前为止，它们是在此光谱范围内开发高效反射镜的唯一可行选择。但是，当前的标准ML具有非常窄的光谱带特征，这与SXR光谱仪的科学要求不兼容。然而，ML技术的最新发展使非周期性叠层的开发可重复且可靠，从而使SXR反射镜的制造在大范围的波长范围内具有很高的效率。在这项工作中，在回顾了SXR系列的最新ML涂层之后，我们研究了使用M型折叠和非周期性叠层开发多波段SXR光谱仪的可能性。在选择了可能的关键谱线之后，还提出并讨论了一些关于八波段光谱仪的折衷研究，从而对其可行性和潜在性能进行了评估。