THE POLAR PLASMA-WAVE INSTRUMENT

The Plasma Wave Instrument on the Polar spacecraft is designed to prov ide measurements of plasma waves in the Earth's polar regions over the frequency range from 0.1 Hz to 800 kHz. Three orthogonal electric dip ole antennas are used to detect electric fields, two in the spin plane and one aligned along the spacecraft spin axis. A magnetic loop anten na and a triaxial magnetic search coil antenna are used to detect magn etic fields. Signals from these antennas are processed by five receive r systems: a wideband receiver, a high-frequency waveform receiver, a low-frequency waveform receiver, two multichannel analyzers; and a pai r of sweep frequency receivers. Compared to previous plasma wave instr uments, the Polar plasma wave instrument has several new capabilities. These include (1) an expanded frequency range to improve coverage of both low- and high-frequency wave phenomena, (2) the ability to simult aneously capture signals from six orthogonal electric and magnetic fie ld sensors, and (3) a digital wideband receiver with up to 8-bit resol ution and sample rates as high as 249k samples s(-1).