PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
LABEL_REVISION_NOTE = "
2016-06-01 JUNO: LEBrown Revision 1;
"
OBJECT = INSTRUMENT
INSTRUMENT_HOST_ID = "JNO"
INSTRUMENT_ID = "JEDI"
OBJECT = INSTRUMENT_INFORMATION
INSTRUMENT_NAME = "JUPITER ENERGETIC-PARTICLE DETECTOR INSTRUMENT"
INSTRUMENT_TYPE = "ENERGETIC PARTICLE DETECTOR"
INSTRUMENT_DESC = "
Juno will be the first spacecraft to fly over the poles of the planet
Jupiter at low altitude. Juno science objectives for the polar
magnetosphere include: Investigate the primary auroral processes
responsible for particle acceleration, characterize the field-aligned
currents that transfer angular momentum from Jupiter to its
magnetosphere, identify and characterize auroral radio and plasma wave
emissions associated with particle acceleration, and characterize the
nature and spatial scale of auroral features.
Juno is ideally suited to determine the auroral distributions of
charged particles due to its low altitude passes through the polar
region of the planet. For the auroral science, The Jupiter Energetic
Particle Detector Instrument (JEDI) will directly measure
precipitating fluxes including particles that generate the planetary
aurora and particles that heat and ionize the planetary
atmosphere. Detailed analysis of the particle spectral and angular
characteristics will be used to study acceleration mechanisms. JEDI
has the capacity through its electron measurements to determine the
magnetic topology of the polar cap region.
Jedi will measure the energetic plasma. The JEDI system covers the
energy range of 25 keV to ❯ 500 keV for electrons, and 10 keV/nucleon
to ~20 MeV total energy for ions. JEDI determines the distributions
of the high-energy magnetospheric ions and electrons, including the
composition of ions. It does this by measuring the energy and
velocity of the particles and then using a look-up table to determine
the mass and therefore the species of particle. The measured species
for JEDI include electrons and ions (H, He, O, S).
Rapid spacecraft motions and slow spacecraft rotation require that
JEDI simultaneously and continuously resolve both magnetic loss cones
at every position inside of ~ 3 RJ. JEDI uses 2 individual
instruments (JEDI-90 and JEDI-270), each with multiple views that
continuously sample within a 360 degree plane roughly normal to the
spacecraft spin axis. All sky coverage is additionally achieved every
spin with an additional sensor (JEDI-A180) that views coplanar to the
spin axis.
Each JEDI sensor consists of a 60 mm diameter, hockey-puck-like
cylinder, in which a start foil and stop foil, wrapped around opposite
curved sides of the cylinder, constitute the time-of-flight chamber.
An incoming energetic ion will pass through the collimator and a
passive thin foil designed to keep the cold plasma out of the
instrument. Then the ion passes through the start foil generating
forward-scattered electrons that are then focused towards a
microchannel plate. The ion will continue through the chamber to the
stop foil, generating backscattered electrons, also accumulated on the
MCP. The ion will then pass into a solid-state detector, providing
the third component of the measurement. Since the time-of-flight
(TOF) can be computed from the start and stop signals and the chamber
size is known, the particle speed can be obtained. The velocity
coupled with the energy yields the ion species. For ions that fall
below the discrimination level of the solid-state detectors, a heavy
vs. light determination can be made with the TOF and the anode pulse
height.
The detectors are arranged so that each detector senses the events
within a given range of incidence angles. One of the JEDI sensors
also contains witness detectors. Each of the six detector modules is
composed of four pixels: large and small ion and large and small
electron. The electron detectors differ from the ion detectors in
that they add a layer of aluminum, which excludes low-energy ions.
Each electron and ion detector is split into a small pixel and a large
pixel; the large pixel has 20 times the area of the small pixel. This
provides 24 detector elements.
"
END_OBJECT = INSTRUMENT_INFORMATION
OBJECT = INSTRUMENT_REFERENCE_INFO
REFERENCE_KEY_ID = "NULL"
END_OBJECT = INSTRUMENT_REFERENCE_INFO
END_OBJECT = INSTRUMENT
END
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