适用于微聚焦X射线源的微纳结构阳极钼靶热管理:热失稳机制及解决策略

Thermal Management of Micro-nano Anodic Molybdenum Targets for Microfocused X-ray Sources:Thermal Instability Mechanisms and Solution Strategies

  • 摘要: 透射式X射线源具有辐射输出对称性好、可调谐性高等优势,适用于高精度、高定制化的辐射应用场景。发展基于微纳结构阳极钼靶的透射式X射线源器件有望实现微聚焦的辐射特性并提高其亮度,但靶材的散热问题是制约X射线辐射剂量和亮度的关键因素。建立了适用于微纳结构阳极钼靶的热响应模型,分析了电子束和透射式靶材结构参数对靶温度分布的影响,最终确定1 μm直径、2.6 μm厚度为钼靶的最佳结构尺寸,实现了辐射性能和热稳定性间的平衡。为进一步解决热失稳问题,提出了一种采用旋转阳极钼靶交替受激的器件热管理策略。理论计算表明,通过引入额外散热途径,该结构可承受高达282.28 mA/cm2电流密度的电子束轰击,较单个微纳结构钼靶提升了44.45倍。该研究为高性能透射式微聚焦X射线源的开发提供了新思路。

     

    Abstract: Transmission-type X-ray sources exhibit significant advantages in customized radiation applications such as high-precision imaging, materials analysis, and medical diagnosis due to their superior radiation output symmetry and highly tunable characteristics. The development of transmission-type X-ray source devices based on micro-nanostructured molybdenum anode targets not only promises to achieve microfocused radiation characteristics and enhanced brightness but also enables more precise X-ray control. However, under high-power operating conditions, thermal management of the target material emerges as a critical bottleneck limiting the enhancement of X-ray radiation dose and brightness. This issue is particularly prominent in practical applications, significantly impacting device longevity and operational stability. A theoretical model for the thermal response of micro - nanostructured molybdenum anode targets was established, comprehensively incorporating heat conduction, radiation heat transfer, and electron beam energy deposition. Through systematic analysis of the relationships among electron beam energy, transmission target structural parameters, and temperature distribution, combined with multi-parameter optimization calculations, the optimal molybdenum target dimensions of 1 μm in diameter and 2.6 μm in thickness were determined, achieving an optimal balance between radiation performance and thermal stability. To further address thermal instability issues, a device thermal management strategy utilizing alternating excitation of rotating molybdenum anode targets was proposed. This strategy significantly enhances heat dissipation efficiency through an innovative rotational mechanism design. Theoretical calculations indicate that by introducing additional heat dissipation pathways, this structure can withstand electron beam bombardment with current densities up to 282.28 mA/cm2, representing a 44.45-fold performance improvement compared to single micro-nanostructured molybdenum targets. These research findings provide crucial theoretical guidance and innovative insights for developing next-generation high-performance transmission-type microfocused X-ray sources, potentially advancing related technologies in high-precision applications. Furthermore, the thermal management strategy proposed in this study serves as a valuable reference for the thermal design of other high-power micro-nanodevices.

     

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