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Instrument: PWI-P : Plasma Waves Investigation (Polar)
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The primary goal of the Polar Plasma Wave Investigation (PWI) is to provide
comprehensive measurements of plasma wave phenomena in the high latitude
auroral zones, in the dayside magnetic cusp regions, and in the plasmasphere
and plasmasheet. Coordinated measurements will be made with the plasma,
energetic particle, imaging, and magnetic field measurements to study local
processes with an emphasis on wave-particle interactions.

The Polar Plasma Wave Investigation employs seven distinct sensors for
detecting the electric and magnetic fields of plasma waves. These sensors
consist of: a pair of orthogonal two-sphere electric antennas in the spin plane
of the spacecraft with sphere-to-sphere separations of 100 meters and 130
meters respectively, shared with the Electric Field Instrument (EFI); a short
two-sphere electric antenna aligned along the spacecraft spin axis with a
sphere-to-sphere separation of 14 meters, also shared with EFI; a triaxial
magnetic search coil mounted on the end of a rigid stacer boom, shared with
EFI; and a magnetic loop antenna mounted on the same boom and oriented parallel
to the 100-meter electric antenna in the spin plane.

The spheres on the electric antennas are 9 cm in diameter and each contains a
high-impedance preamplifier that provides signals to the boom deployment
mechanisms. Amplifiers in the deployment mechanisms buffer signals to EFI and
PWI independently. Each of the three magnetic search coils consists of two
bobbins mounted on high permeability micro-metal cores 40cm long. Each bobbin
is wound with 10,000 turns of #40 wire. The coil outputs are amplified by a
preamplifier in the search coil housing to provide a low-impedance signal to
the main electronics box. The search coil sensitivity constant is 70 micro
V/nT-Hz and the resonance frequency is approximately 10 kHz. The loop antenna
is similar to the magnetic loop antenna on Dynamics Explorer A and is designed
to detect magnetic fields over a frequency range from 25 Hz to 800 kHz. The
loop sensitivity constant is 385 micro V/nT-Hz and the resonance frequency is
45 kHz.

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Instrument Logistics
Instrument Start Date: 1996-02-24
Instrument Owner: University of Iowa