Study on the advanced electric field measurement system in space plasmas

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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.