DOI: 10.48322/4e3s-bm07
title: DE 1 Retarding Ion Mass Spectrometer (RIMS) Low Channel, H+ and He++, and High Channel, He+, O+, and O++, Density, Temperature, and Electric Potential, 1 min Data

description: 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-u 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 in the Energy Range from 0 eV to 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 (5) The detailed Composition of Ionospheric Plasma in the Range from 1-u to 32-u He++ and O++ were also measured. The Instrument consisted of three Detector Heads. One looked out in the Radial Direction, and the other two looked out along the Plus and Minus Spin Axis Directions. Each Detector had a 55° 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-u to 32-u. The Time Resolution was 16 ms. Additional Details can be found in C.R. Chappell et al., Space Sci. Instrum., 5(4), 477, 1981. The Criterion for selecting Data Points to be appropriate for fitting include that the Aperature Bias equal to zero must have at least ten or more Non-Zero Points in the RPA Curve. If the Spacecraft Altitude was less that 1.3 Re, the High Voltage Monitor must be turned on, the Maximum Counter Rate Value must at least 5.0, and there must be at least four Points starting from the End of RPA Curve. Find three consecutive Points of increasing Value, reset the End of the RPA Curve to here and make certain that the last Point is one Sigma above the Noise Level (the Points excluded in previous Step). if not, then drop a Point and check the new last Point, continue until the Criteria is met. One must have at least three Points left starting at new End of the selected RPA Curve Stop first Point greater that 80% of the Maximum of Spin Curve. If not found, stop at the last Point that is less than the Maximum. There must be at least three Points left. Change the Curve from the Count Rate Curve to the l**2 Curve. If Number of Points are five or less, then do a Linear Least Squares Fit (LINFIT) to the Data. If the Linear Correlation Coefficient (LCC) greater than 0.8 then the Points will be used, if not, the data set is discarded. If the Number of Points are greater then five, then do a LINFIT to the bottom five and a LINFIT to the top five Points. If there are six or more Points, then apply LINFIT to the middle Set of five Points, saving the LCC and Slope for each Case. If all three LCCs are less than 0.800, then discard the Data Set. Through a Series of Tests, find the Set of five Points with the best LCC Slope Combination. Once the Set of five Points has been selected, add the Rest of the Points one at a time and recompute the LLC with LINFIT, if the LCC gets worse discard the added Point otherwise keep it, do this until all Points are checked. Once this Procedure is completed, the final Set of Points have been determined.