We report the mirror suspension design for large-scale cryogenic gravitational wave telescope, KAGRA, during bKAGRA phase 1. Mirror thermal noise is one of the fundamental noises for room-temperature gravitational-wave detectors such as Advanced LIGO and Advanced Virgo. Thus, reduction of thermal noise is required for further improvement of their sensitivity. One effective approach for reducing thermal noise is to cool the mirrors. There are many technical challenges that must be overcome to cool the mirrors, such as cryocooler induced vibrations, thermal drift in suspensions, and reduction in duty cycling due to the increased number of potential failure mechanisms. Our mirror suspension has a black coating that makes radiative cooling more efficient. For conduction cooling, we developed ultra high purity aluminum heat links, which yield high thermal conductivity while keeping the spring constant sufficiently small. A unique inclination adjustment system, called moving mass, is used for aligning the mirror orientation in pitch. Photo-reflective displacement sensors, which have a large range, are installed for damping control on marionette recoil mass and intermediate recoil mass. Samarium cobalt magnets are used for coil-magnet actuators to prevent significant change of magnetism between room temperature and cryogenic temperature. In this paper, the design of our first cryogenic payload and its performance during bKAGRA phase 1 are discussed.

我们报告了 bKAGRA 阶段 1 期间大型低温引力波望远镜 KAGRA 的反射镜悬挂设计。反射镜热噪声是诸如 Advanced LIGO 和 Advanced Virgo 等室温引力波探测器的基本噪声之一。因此，需要降低热噪声以进一步提高其灵敏度。降低热噪声的一种有效方法是冷却反射镜。要冷却反射镜，必须克服许多技术挑战，例如低温冷却器引起的振动、悬架中的热漂移以及由于潜在故障机制数量增加而导致的占空比减少。我们的后视镜悬架具有黑色涂层，可提高辐射冷却效率。对于传导冷却，我们开发了超高纯度铝热链，在保持弹簧常数足够小的同时产生高热导率。一个独特的倾斜调整系统，称为移动质量，用于在俯仰中对齐反射镜方向。安装了具有大范围的光反射位移传感器，用于对牵线木偶后坐质量和中间后坐质量进行阻尼控制。钐钴磁铁用于线圈磁铁致动器，以防止室温和低温之间的磁性发生显着变化。在本文中，我们讨论了我们的第一个低温有效载荷的设计及其在 bKAGRA 第一阶段的性能。射程大，用于对牵线木偶后坐质量和中间后坐质量进行阻尼控制。钐钴磁铁用于线圈磁铁致动器，以防止室温和低温之间的磁性发生显着变化。在本文中，我们讨论了我们的第一个低温有效载荷的设计及其在 bKAGRA 第一阶段的性能。射程大，用于对牵线木偶后坐质量和中间后坐质量进行阻尼控制。钐钴磁铁用于线圈磁铁致动器，以防止室温和低温之间的磁性发生显着变化。在本文中，我们讨论了我们的第一个低温有效载荷的设计及其在 bKAGRA 第一阶段的性能。