日本地球惑星科学連合2018年大会

講演情報

[EE] Eveningポスター発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM16] Dynamics of Earth's Inner Magnetosphere and Initial Results from Arase

2018年5月22日(火) 17:15 〜 18:30 ポスター会場 (幕張メッセ国際展示場 7ホール)

コンビーナ:Danny Summers(Memorial University of Newfoundland)、三好 由純(名古屋大学宇宙地球環境研究所)、細川 敬祐(電気通信大学大学院情報理工学研究科、共同)、海老原 祐輔(京都大学生存圏研究所)

[PEM16-P27] Calibration of Waveform Data Measured by the Plasma Wave Experiment (PWE) on board the ARASE (ERG) Satellite

*西澤 宏幸1太田 守1松田 昇也2笠原 禎也1後藤 由貴1 (1.金沢大学、2.名古屋大学)

キーワード:プラズマ波動・電場観測機器、波形捕捉受信器、較正

The Plasma Wave Experiment (PWE) on board the Arase satellite measures electric field from DC to 10 MHz, and magnetic field from a few Hz to 100 kHz. The waveform capture (WFC) is one of subsystems of the PWE and is dedicated to measuring waveform for the two electric components and three magnetic field components. The WFC nominally covers the frequency range below 20 kHz, which is crucial for the measurements of chorus, hiss and magnetosonic waves. It is necessary to calibrate the WFC data in order to correctly reproduce the waveform actually measured by the sensors. In the present paper, we introduce the calibration method of the WFC data using inverse filter.

We applied the calibration tables, in which the frequency responses of sensors and receivers of the WFC are defined, provided by the Arase/PWE team. We first designed inverse filters by taking the inverse of the transfer functions of the WFC and performing the inverse FFT. In the process, we determined cutoff frequencies comparing the reproduced waveform with standard signals generated by the known signal source inside the PWE. This method is effective because waveforms can be calibrated continuously without periodical joint, although the computational complexity is large. As a future work, it is necessary to examine a method of correcting waveform distortion due to receiver nonlinearity. We also note that the electric field intensity is provisionally calibrated under the assumption of combining the theoretical antenna capacitance in a vacuum, and the typical plasma resistance. We also correct this point by comparing the refractive index obtained from both the electric field and the magnetic field waveforms with the theoretical value.