Detector of Ions and Neutral Atoms (DINA)

Specifications

Measurement principles:
The instrument consists of two sensors with the aperture 5 * 30 degree each. The sensor DINA-0 is looking at 180 degree pitch-angle and DINA-90 at 90 degree pitch-angle. Over the Northern hemisphere DINA-0 provides measurements of the ion precipitating flux during the auroral oval crossing. While the spacecraft moves through the polar cup, DINA-90 makes measurements of ENA flux from the exobase at one local time sector. Over the Southern hemisphere DINA-90 would measure exobase ENA flux from a different local time sector due to uncontrolled azimuthal motion of the spacecraft. DINA-0 pointing down in the Southern hemisphere is aimed to detect outflowing ENA in the precipitation region. The information about input ion flux can be obtained from the DINA-90 measurements because the precipitating ion distribution can be considered approximately isotropic.

The instrument performs alternative measurements of ions and energetic atoms by turning on and off high voltage on the electrostatic deflection system with the cut-off energy 280 keV (140 keV for the single HV supply design). Electrons with the energy up to 200 keV are swept away by permanent broom magnets.

Mass identification is performed by (Delta E) / E detectors (E / E detectors). For the energy range 20 - 100 keV, the front detector will provide integral flux of all masses. (The range is the detector - dependant and will be exactly defined later by calibrations. 100 keV corresponds to a 1 m front detector and 20 keV to a 0.05 mm deadlayer). For energies above 100 keV, the coincidence and anti-coincidence logic provides measurements of hydrogen and helium (coincidence front and back detectors) and particles with A > 4, mainly, oxygen (anti-coincidence front and back detectors).

Instrument characteristics:
Energy range (protons or H atoms) 20 - 500 keV
Masses to resolve A = 1, 4, A > 4 for E > 100 keV
Particles to measure ions, neutrals
Aperture per sensor 5 * 30
Angular resolution 2.5 * 25
G-factor / sector 2.5 * 10-3 cm2sr
Deflector cut-off energy 280 keV
140 keV for a single HV supply design
Deflection system transmittance < 5 * 10-4 for E < 140 keV
< 10-2 for E < 280 keV

Heritage:
The electrostatic deflector system and partially electronics are from the PIPPI experiment on board the microsatellite Astrid.

New developments:
Implementation of the E / E detectors is a new development.

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