AMPTE-IRM

The main instrument consisted of two symmetrical quadrispherical electrostatic analyzers to measure the three-dimensional distributions of electrons and ions, respectively, over 4-pi-sr during every satellite spin period (4 seconds). The energy range covered was 15 eV/Q to 30 keV/Q in 30 channels. The angular resolution was 22.5°. Moments of the measured distributions were directly computed on board. An additional retarding-potential analyzer measured the flux of electrons between approximately 0 and 25 eV.[4]

The experiment consisted of eight lithium and eight barium canisters, which were injected from the AMPTE-IRM in pairs by ground command and ignited 10 minutes after separation from the spacecraft. Each of these was either totally lithium or totally barium. A pair of Li/Ba canisters produced a total of 2.E25/7.E24 Li/Ba atoms, respectively, which were subsequently ionized by solar radiation. Li releases in the solar wind, which were carried out in August/September 1984, were to be followed by an artificial comet release of Ba ions in the dawnside magnetosheath and a number of Ba and Li releases in the geomagnetic tail. In situ diagnostics by AMPTE-IRM and AMPTE-UKS and optical observations of the clouds from the ground were followed by tracing of the ions in the inner magnetosphere by AMPTE-CCE.[5]

The instrument consisted of a retarding-potential analyzer entrance section and a toroidal electrostatic energy-per-charge analyzer, followed by a quadrispherical electrostatic analyzer with superimposed radial magnetic field for mass-per-charge analysis. The energy range covered was approximately 0 to 12 (or 24) keV/Q, with adequate mass resolution to separate the Li and Ba tracer ions. Up to eight different ion species could be analyzed simultaneously.[6]

The instrument used a 42 m (138 ft) tip-to-tip antenna to measure electric fields from DC to 5 MHz and two boom-mounted search coil magnetometers to measure magnetic fields from 30 Hz to 1 MHz. The signals were analyzed by a very low frequency VLF/MF 16-channel spectrum analyzer, three VLF narrow-band swept-frequency receivers, a 60-channel high frequency HF stepped-frequency receiver, and an analog wide-band receiver.[7]

The main instrument consisted of a curved plate electrostatic energy-per-charge analyzer followed by a 12 cm (4.7 in) time-of-flight telescope with a thin carbon foil at the front and a solid-state detector at the rear, which measured ion velocity and residual energy. The energy-per-charge range was 10 to 300 keV/Q. The mass resolution, delta M/M, ranged from 0.25 to 0.12. The instrument package also contained an electron sensor for the energy range 35 to 220 keV, provided by University of California, Berkeley.[8]

The instrument was a three-axis fluxgate magnetometer mounted on a 2 m (6 ft 7 in) boom. It had two switchable ranges (± 4 microtesla, and ± 60 microtesla) with resolutions of 0.12 and 1.8 nT, respectively and was read out at 32, 16, 8, or 4 vector samples per second, depending on the T/M rate. Signals from each sensor were also fed into four band pass filters with 5.5, 11, 22, and 44-Hz center frequencies and were read out up to two times per second.[9]