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

我们开展了基础研究，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，经常遇到观测数据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，通过多个航天器进行同时观测是必不可少的。在多航天器的使命设计中，对星载仪器的重量和尺寸要求非常严格，因此需要对仪器进行小型化。一个典型的等离子体波接收器系统比其他仪器具有更多的模拟部件。因此，我们尝试使用模拟ASIC技术在单芯片LSI内实现等离子体波接收器系统的模拟部分。设计了第一级差分放大器、低通滤波器和带共模反馈环的主放大器，稳定了各放大器的功能。由于100 kHz的上限频率很低，在模拟ASIC中不可能实现电容和电感低通滤波器，我们设计了利用ASIC内部FET电导的gm-C滤波器。我们还进行了ASIC芯片内部连接模式的布局，并将设计提交给制造商。我们使用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，我们利用三维模型进行了等离子体中天线的响应。等离子体中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等离子体参数、等离子体鞘层和光电子。我们建立了适用于这个主题的模拟程序，并使用各种等离子体条件检查天线响应。

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.