Next Generation High Stability, Long-Life Mercury Ion Clocks for Ground and Space Applications

With its 40+ year history, mercury ion clocks have demonstrated excellent performance in both ground and space applications. The microwave-based technology has resulted in observations of mercury clocks with relative frequency stability ranging from nearly 1E-14/1E-16 (measured at 1s/1E4s, respectively) [Tjoelker et al. (1996), Dick et al. (1998), Burt et al. (2008)] in clocks with a 200L volume to 1E-11/1E-13 (measured at 1s/1E4s, respectively) in a 1L volume [Hoang et al. (2023)]. A recently completed space-based mercury ion clock technology demonstration mission (NASA Deep Space Atomic Clock (DSAC) [Tjoelker et al. (2016), Burt et al. (2021)]) had a relatively compact form factor (∼19L) and proved the ability of the technology to support 5 year life with a fractional frequency stability from 2E-13 to 2E-15 (measured at 1s/1E4s, respectively) and long term drift <3E-16/day. This low drift, 1-2 orders of magnitude lower than other currently operating space clocks based on other principles, illustrates this technology’s utility for applications requiring autonomy. The relatively long clock life along with its low sensitivity to ambient temperature and magnetic field makes the device promising for future critical space (e.g. GNSS) and ground (e.g. NASA Deep Space Network) applications. We here report on targeted R&D efforts following the DSAC mission towards the development of a manufacturable clock prototype intended for future ground and flight applications that require hydrogen maser level stability performance and reliability. We present the clock concept, which is designed to reduce the clock’s size, weight and power consumption (SWaP) while still maintaining or even improving performance. We developed a new compact quadrupole ion trap configuration supporting long clock transition coherence time observations exceeding similar parameters of DSAC by an order of a magnitude. Lifetime and reliability considerations of the clock’s critical components will also be addressed. Finally, the importance of the local oscillator utilized in the clock is illustrated and a possibility of implementation of a compact mercury clock with 4E-15 to 2E-16 stability (measured at 1s/1E4s, respectively) is discussed.

汞离子钟（mercury ion clock）历经四十余年发展，已在地面与航天应用中展现出优异性能。采用微波技术路线的汞离子钟，200升体积型号的相对频率稳定度可达近1×10^-14/1×10^-16（分别在1秒/10^4秒下测量）[Tjoelker等，1996；Dick等，1998；Burt等，2008]；而1升体积型号则可达1×10^-11/1×10^-13（分别在1秒/10^4秒下测量）[Hoang等，2023]。
近期完成的天基汞离子钟技术验证任务——美国国家航空航天局（NASA）深空原子钟（Deep Space Atomic Clock, DSAC）[Tjoelker等，2016；Burt等，2021]，其外形相对紧凑（约19升），验证了该技术支持5年服役寿命的能力：其相对频率稳定度范围为2×10^-13至2×10^-15（分别在1秒/10^4秒下测量），长期漂移小于3×10^-16/天。
该极低漂移性能较当前其他原理在轨时钟低1~2个数量级，彰显了此项技术在自主运行需求场景中的应用价值。该钟不仅服役寿命较长，且对环境温度与磁场敏感度低，使其有望应用于未来关键航天（如全球导航卫星系统GNSS）与地面（如NASA深空网）场景。
本文针对DSAC任务后的定向研发工作进行汇报，旨在开发可量产的汞离子钟样机，以满足未来对氢激射器（hydrogen maser）级稳定度与可靠性需求的地面与航天应用。本文提出了该钟的设计方案，旨在在维持甚至提升性能的同时，降低钟的尺寸、重量与功耗（SWaP）。我们研发了新型紧凑四极离子阱结构，其支持的钟跃迁相干时间观测时长较DSAC提升了一个数量级。本文还将探讨该钟关键组件的寿命与可靠性相关问题。最后，本文阐明了钟内置本地振荡器的重要性，并探讨了实现稳定度达4×10^-15至2×10^-16（分别在1秒/10^4秒下测量）的紧凑型汞离子钟的可行性。

搜集汇总

背景与挑战

背景概述

该数据集聚焦于下一代高稳定性、长寿命汞离子钟的研发，基于40多年历史的技术，在空间和地面应用中表现出卓越性能，如NASA深空原子钟（DSAC）任务展示的紧凑设计、5年寿命、低至2E-13到2E-15的频率稳定性和低于3E-16/天的长期漂移。数据集报告了DSAC后的研发进展，旨在开发可制造的时钟原型，通过减小尺寸、重量和功耗（SWaP）并提升性能，支持未来关键空间和地面应用，同时讨论了新紧凑四极离子阱配置和实现更高稳定性的可能性。