Study on the advanced electric field measurement system in space plasmas

1.低噪声前置放大器的开发：由于我们需要检测信号电平非常低的等离子体波，大约为几nV/m/sqrt(Hz)，因此开发极低噪声前置放大器非常重要。特别是在下一代，我们计划观察邻近等离子体的热波动信号，以了解局部等离子体的密度和温度等参数。我们成功地研制了频率范围宽至10mhz的极低噪声前置放大器。轻型碳纤维天线：碳纤维天线作为电场传感器向自转轴方向延伸，是未来任务中最有可能的电场天线。由于它是由缠绕的碳纤维制成的，我们担心高频范围内电感的影响。我们对碳纤维天线进行了现场测试，证实其效率足够高，可用于航天任务。机载天线阻抗测量系统设计：基于相干检测法设计了精密的机载电场传感器测量系统。实现了具有良好信噪比的天线阻抗测量。天线阻抗的计算机实验：我们开发了三维模拟程序，可以处理真实的航天器形状和天线在真实的等离子体条件下，如密度和温度。它还具有处理光电子动力学的能力。我们研究了附近等离子体条件对天线阻抗的影响。先进轻便的电场接收器：我们尝试使用ASIC技术将典型等离子体波接收器系统的模拟部分集成到一个芯片上。研制的芯片在电磁屏蔽室内进行了测试，验证了其功能。

1.Development of the low noise preamplifier : Since we need to detect plasma waves with very low signal levels in the order of a few nV/m/sqrt(Hz), the development of the very low noise preamplifier is important. Especially, in the next generation, we have a plan to observe the thermal fluctuation signals of the vicinity plasmas in order to know the local plasma parameters such as densities and temperatures. We succeeded in developing the very low noise preamplifier with the wide frequency range up to 10MHz.2.Light-weight carbon fiber antenna : The carbon fiber antenna is the most plausible electric field antenna in the next mission as the electric field sensor extending to the spin axis direction. Since it is made of winding carbon fibers, we worried about the effect of the inductance in the high frequency range. We conducted the field tests for the carbon fiber antennas and confirmed the efficiency is high enough to be used in the space mission.3.Design of the onboard antenna impedance measurement system : We designed the sophisticated onboard measurement system of electric field sensors based on the coherent detection method. It realizes the measurement of antenna impedance with good S/N ratio.4.Computer experiments on antenna impedance : We developed 3-dimensional simulation program which can handle the realistic spacecraft shape and antennas under realistic plasma conditions such as densities and temperatures. It also has the capability to treat the dynamics of photo electrons. We investigated the effects of the vicinity plasma conditions to the antenna impedance.5.Advance and light weight electric field receiver : We attempted to integrate the analog parts of the typical plasma wave receiver system into one-chip device by using the ASIC technology. The developed chip was tested inside the electromagnetic shield chamber and confirmed its functions.