NEI (Impedance Probe)

The purpose of the measurement

The purpose is to obtain the accurate electron density (absolute value) profile during the diffuse auroral event in the polar region by the standard Impedance Probe.

Abstract of the instrument

NEI measures the equivalent capacitance of ribbon antenna (1.2m in extent, 15mm in diameter) between the 300 kHz to 10 MHz to determine the Upper Hybrid Resonance (UHR) frequency of the ambient plasma. Then, the accurate electron number density is derived from the detection of UHR frequency.

Sensor1.2 m ribbon antenna (BeCu)
Sweep frequency range300 kHz - 10.3 MHz
Sweep time500ms
Measurable equivalent capacitance1 pF - 400 pF
Measurable electron number density1x103 - 1.30x106 /cc
Weight0.86 kg
Power+18 V, 250 mV


T. Ono(Tohoku Univ.), M. Wakabayashi(Tohoku Univ.), T. Koshida (Tohoku Univ.), System-Keisoku Co., Inc.