The Radio Plasma Imager investigation on the IMAGE spacecraft

B.W. Reinisch (1), D. M. Haines (1), K. Bibl (1), G. Cheney (1), 
I.A. Galkin (1), X. Huang (1), S.H. Myers (1), G.S. Sales (1), 
R.F. Benson (2), S.F. Fung (2), J.L. Green (2), S. Boardsen (3), 
W.W.L. Taylor (3), J.-L. Bougeret (4), R. Manning (4), N. Meyer-Vernet (4), 
M. Moncuquet (4), D.L. Carpenter (5), D.L. Gallagher (6) and P. Reiff (7)

1 University of Massachusetts, Center for Atmospheric Research, Lowell, MA,
2 NASA Goddard Space Flight Center, Greenbelt, MD, 
3 Raytheon ITSS, Goddard Space Flight Center, Greenbelt, MD, 
4 Observatoire de Paris, Meudon, France, 
5 Stanford University, Stanford, CA, 
6 NASA Marshall Space Flight Center, Huntsville, AL, 
7 Rice University, Houston, TX


Abstract.  Radio plasma imaging uses total reflection of electromagnetic
waves from plasmas whose plasma frequencies equal the radio sounding
frequency and whose electron density gradients are parallel to the wave
normals. The Radio Plasma Imager (RPI) has two orthogonal 500-m long dipole
antennas in the spin plane for near omni-directional transmission. The
third antenna is a 20-m dipole along the spin axis. Echoes from the
magnetopause, plasmasphere and cusp will be received with the three
orthogonal antennas, allowing the determination of their angle-of-arrival.
Thus it will be possible to create image fragments of the reflecting
density structures. The instrument can execute a large variety of
programmable measuring options at frequencies between 3 kHz and 3 MHz.
Tuning of the transmit antennas provides optimum power transfer from the 10
W transmitter to the antennas. The instrument can operate in three active
sounding modes: (1) remote sounding to probe magnetospheric boundaries, (2)
local (relaxation) sounding to probe the local plasma frequency and scalar
magnetic field, and (3) whistler stimulation sounding. In addition, there
is a passive mode to record natural emissions, and to determine the local
electron density, the scalar magnetic field, and temperature by using a
thermal noise spectroscopy technique. 

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Space Science Reviews, IMAGE Special Issue, Vol. 91, pp. 319-359, February, 2000