The Plasma Wave Investigation (PWI) aboard the BepiColombo Mio (Mercury Magnetospheric Orbiter, MMO) will enable the first observations of electric fields, plasma waves, and radio waves in and around the Hermean magnetosphere and exosphere. The PWI has two sets of receivers (EWO with AM 2 P, SORBET) connected to two electric field sensors (MEFISTO and WPT) and two magnetic field sensors (SCM: LF-SC and DB-SC). After the launch on October 20, 2018, we began initial operations, confirmed that all receivers were functioning properly, and released the launch locks on the sensors. Those sensors are not deployed during the cruising phase, but the PWI is still capable performing magnetic field observations. After full deployment of all sensors following insertion into Mercury orbit, the PWI will start its measurements of the electric field from DC to 10 MHz using two dipole antennae with a 32-m tip-to-tip length in the spin plane and the magnetic field from 0.3 Hz to 20 kHz using a three-axis sensor and from 2.5 kHz to 640 kHz using a single-axis sensor at the tip of a 4.5-m solid boom extended from the spacecraft’s side panel. Those receivers and sensors will provide (1) in-situ measurements of electron density and temperature that can be used to determine the structure and dynamics of the Hermean plasma environment; (2) in-situ measurements of the electron and ion scale waves that characterize the energetic processes governed by wave–particle interactions and non-MHD interactions; (3) information on radio waves, which can be used to remotely probe solar activity in the heliocentric sector facing Mercury, to study electromagnetic-energy transport to and from Mercury, and to obtain crustal information from reflected electromagnetic waves; and (4) information concerning dust impacts on the spacecraft body detected via potential disturbances. This paper summarizes the characteristics of the overall PWI, including its significance, its objectives, its expected performance specifications, and onboard and ground data processing. This paper also presents the detailed design of the receiver components installed in a unified chassis. The PWI in the cruise phase will observe magnetic-field turbulence during multiple flybys of Earth, Venus, and Mercury. After the Mercury-orbit insertion planned at the end of 2025, we will deploy all sensors and commence full operation while coordinating with all payloads onboard the Mio and MPO spacecraft.

中文翻译：

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BepiColombo Mio 上的等离子波调查 (PWI) 首次测量水星周围的电场、电磁波和无线电波

BepiColombo Mio（水星磁层轨道器，MMO）上的等离子体波调查 (PWI) 将能够对 Hermean 磁层和外逸层内部和周围的电场、等离子体波和无线电波进行首次观测。PWI 有两套接收器（EWO with AM 2 P，SORBET）连接到两个电场传感器（MEFISTO 和 WPT）和两个磁场传感器（SCM：LF-SC 和 DB-SC）。2018 年 10 月 20 日发射后，我们开始了初步操作，确认所有接收器功能正常，并释放了传感器上的发射锁定。这些传感器不会在巡航阶段部署，但 PWI 仍然能够执行磁场观测。在插入水星轨道后所有传感器完全部署后，PWI 将使用两个偶极天线开始测量从 DC 到 10 MHz 的电场，在自旋平面中的尖端到尖端长度为 32 米，并使用三轴传感器测量从 0.3 Hz 到 20 kHz 的磁场以及从 2.5 kHz 到 640 kHz，在从航天器侧板伸出的 4.5 米实心吊杆尖端使用单轴传感器。这些接收器和传感器将提供 (1) 电子密度和温度的原位测量，可用于确定 Hermean 等离子体环境的结构和动力学；(2) 电子和离子尺度波的原位测量，表征由波粒相互作用和非 MHD 相互作用控制的能量过程；(3) 无线电波信息，可用于远程探测面向水星的日心扇区的太阳活动，研究进出水星的电磁能量传输，并从反射的电磁波中获取地壳信息；(4) 通过潜在扰动检测到的有关尘埃对航天器主体的影响的信息。本文总结了整体 PWI 的特点，包括其意义、目标、预期性能规格以及机载和地面数据处理。本文还介绍了安装在统一机箱中的接收器组件的详细设计。巡航阶段的 PWI 将在多次飞越地球、金星和水星期间观察磁场湍流。在计划于 2025 年底插入水星轨道后，我们将部署所有传感器并开始全面运行，同时与 Mio 和 MPO 航天器上的所有有效载荷进行协调。