Study on ion-wave-plasmas interactions in space plasmas via spacecraft observations and computer experiments-Breakthrough of the magnetospheric physics

我们开展基础研究，通过航天器观测和计算机实验，在空间等离子体物理和磁层物理研究方面取得突破。在航天器观测中，常常会遇到观测数据中的时间变化和空间变化不能分离的困难。为了解决这一问题，多个航天器的同时观测是必不可少的。由于在多航天器的任务设计中，对机载仪器的重量和尺寸的要求非常严格，我们需要对仪器进行小型化。与其他仪器相比，典型的等离子体波接收系统具有更多的模拟部件。因此，我们尝试用模拟ASIC技术在单片LSI中实现等离子体波接收系统的模拟部分。设计了第一级差动放大器、低通滤波器和带共模反馈环的主放大环，稳定了每个放大器的功能。由于100 kHz的频率上限很低，利用模拟ASIC内部的电容和电感来实现低通滤波器是不可能的，我们设计了利用ASIC内部FET的电导来实现低通滤波器的Gm-C滤波器。我们还对ASIC芯片内部的连接图案进行了版图设计，并将设计提交给了制造商。我们使用所制造的芯片进行了功能测试和特性测试。结果将反映到下一次设计中。在计算机实验中，我们利用三维模型对等离子体中的天线响应进行了研究。等离子体中的天线作为电场传感器的特性非常复杂。它们强烈地依赖于附近的等离子体参数、等离子体鞘和光电子。我们建立了适用于本课题的模拟程序，并考察了不同等离子体条件下天线的响应。

We conducted the fundamental research to make a breakthrough in the study on space plasma physics and magnetospheric physics via spacecraft observations and computer experiments. In spacecraft observations, we always meet the difficulty that we cannot separate the time variation and spatial variation in the observation data. In order to resolve this problem, the simultaneous observations via multiple spacecraft are essential. Since the requirements on weight and size of onboard instruments are very strict in the mission design of multiple spacecraft, we need to miniaturize our instruments. A typical plasma wave receiver system has more analogue parts than other instruments. Therefore, we attempted to realize the analogue parts of a plasma wave receiver system inside a one-chip LSI using the analogue ASIC technology. We design the first stage differential amplifier, low pass filter, and main amplifier with common mode feedback loops, which are stabilize the functions of each amplifier. Since the upper limit frequency of 100kHz is very low, it is impossible to realize the low pass filter using capacitance and inductance inside a analogue ASIC, we designed the gm-C filter, which make use of the conductance of FET inside the ASIC. We also conducted the layout of the connection pattern inside the ASIC chip and submitted the design to the manufacturer. We conducted the function tests and characteristic tests using the manufactured chips. The results will be reflected to the next design. In the computer experiments, we conducted the antenna response in plasmas using the 3-D model. The characteristics of antennas in plasmas as electric field sensors are very complicated. They are strongly depend on the vicinity plasma parameters, plasma sheath, and photo electrons. We established the simulation program for applying to this subject and examined the antenna response using the various plasma conditions.