The data were provided by Dennis Gallagher (MSFC). The Retarding Ion Mass Spectrometer (RIMS) consisted of a retarding potential analyzer for energy analysis in series with a magnetic ion-mass spectrometer for mass analysis. Multiple sensor heads permitted the determination of the thermal plasma flow characteristics. This instrument was designed to operate in two basic commandable modes: a high-altitude mode in which the density, temperature, and bulk-flow characteristics of principally H+, He+, and O+ ions were measured; and a low-altitude mode that concentrated on the composition in the 1- to 32-u range. This investigation provided information on (1) the densities of H+, He+, and O+ ions in the ionosphere, plasmasphere, plasma trough, and polar cap (including the density distribution along the magnetic vector in the vicinity of the satellite apogee); (2) the temperature of H+, He+, and O+ ions in the ionosphere, plasmasphere, plasma trough, and polar cap (energy range 0-45 eV); (3) the bulk flow velocities of H+, He+, and O+ in the plasmapause, plasma trough and polar cap; (4) the changing character of the cold plasma density, temperature, and bulk flow in regions of interaction with hot plasma such as at the boundary between the plasmasphere and the ring current; and (5) the detailed composition of ionospheric plasma in the 1-to 32-u range. He++ and O++ were also measured. The instrument consisted of three detector heads. One looked out in the radial direction, and the other two were along the plus and minus spin-axis directions. Each detector had a 55-deg half-cone acceptance angle. The detector heads had a gridded, weakly collimating aperture where the retarding analysis was performed, followed by a parallel plate ceramic magnetic mass analyzer with two separate exit slits corresponding to ion masses in the ratio 1:4. Ions exiting from these slits were detected with electron multipliers. In the apogee mode, the thermal particle fluxes were measured while the potential on a set of retarding grids was stepped through a sequence of settings. In the perigee mode, the retarding grids were grounded and the detector utilized a continuous acceleration potential sweep that focused the mass ranges from 1 to 8, and 4 to 32 u. Time resolution was 16 msec. Additional details can be found in C. R. Chappell et al., Space Sci. Instrum., v. 5, n. 4, p. 477, 1981.

Criterian for selecting data points to be fitted aperature bias = 0 must have at least 10 or more non-zero points in rpa curve.  if less that 1.3 Re high voltage monitor must be turned on maximum countr rate value must at least 5.0 must have at least 4 points starting from end of rpa curve find 3 consecutive point of increasing value, reset end of rpa curve to here make certain last point is 1 sigma above noise level (the points excluded in previous step), if not drop point and check new last point, continue until criteria is met, must have at least 3 points left starting at new end of selected rpa curve stop first point greater that 80% of maximum of spin curve, if non found stop at last point less that maximum, must have at least 3 points left change curve from count rate curve to l**2 curve if number of points are 5 or less: do a linear least squares fit (linfit) to the data, if the linear correlation coefficient (lcc) greater than 0.800 then points will be used, if not, data set is discarded if number of points are greater then 5: do a linfit to the bottom 5 and a linfit to the top 5 points, in 6 or more points do linfit to the middle 5, saving the lcc and slope for each case. if all three lccs are less than 0.800 discard data set through a series of tests find the set of 5 with the best lcc slope combination once set of 5 has been selected add rest of points one at a time and redo linfit, if lcc gets worse discard point otherwise keep it, do this until all points are checked we now have the points to be used

More information on DE-1 Retarding Ion Mass Spectrometer is available at 

Two Dynamics Explorer (DE) spacecraft were launched August 3, 1981, and placed into coplanar polar orbits with DE-1 in a highly elliptical orbit and DE-2 in a lower more circular orbit. The primary objective of the DE program was to investigate magnetosphere-ionosphere-atmosphere coupling processes.

The DE mission provided a wealth of new information on a wide variety of magnetospheric plasma wave phenomena including auroral kilometric radiation, auroral hiss, Z mode radiation, narrow-band electromagnetic emissions associated with equatorial upper hybrid waves, whistler mode emissions, wave-particle interactions stimulated by ground VLF transmitters, equatorial ion cyclotron.emissions, ion Bernstein mode emissions, and electric field turbulence along the auroral field lines. 

DE-1 Retarding Ion Mass Spectrometer 1-min temperature and density data (low channel used for H+, He++, high channel for He+, O+, O++)

H+ Temperature in eV, detector head in positive z-direction (spin axis)

H+ Temperature in eV, detector head in negative z-direction (spin axis)

H+ density in cm-3, fit to radial head data with temp-z held constant

Density from fit to radial head data with temperature (temp_z) held constant

Potential from fit to radial head data with temperature (temp_z) held constant

H+ density in cm-3, radial head data with potential (avg_pot) held constant

Density from fit to radial head data with potential (avg_pot) held constant

Temperature from fit to radial head data with potential (avg_pot) held constant

Chi-squared of fit to radial head data with potential (avg_pot) held constant

Flag for fit to radial head data with potential (avg_pot) held constant

H+ Temperature values minus standard deviation (StD) in K, +z head

n (H+) from fit to radial head data with temp held constant (temp_z-STD)

H+ density from fit to radial head data with potential (avg_pot) held constant, T-STD

+++ Temperature values plus standard deviation (STD): H+ temperature in K plus STD, +z head

n (H+) from fit to radial head data with temp held constant (temp_z+STD)

H+ density from fit to radial head data with potential (avg_pot) held constant, T+STD


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