PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
LABEL_REVISION_NOTE = "NULL"
OBJECT = INSTRUMENT
INSTRUMENT_HOST_ID = "SUISEI"
INSTRUMENT_ID = "ESP"
OBJECT = INSTRUMENT_INFORMATION
INSTRUMENT_NAME = "SOLAR-WIND EXPERIMENT"
INSTRUMENT_TYPE = "PLASMA EXPERIMENT"
INSTRUMENT_DESC = "
Instrument Overview
===================
The objective of this experiment is to measure the
three-dimensional velocity distributions of the
solar-wind ions and electrons in the energy range
from 30 eV up to 16 keV within +/- 30deg of the
ecliptic plane. During the cometary encounter, the
interaction of the solar wind with the cometary
ionosphere will be investigated, paying particular
attention to the mass loading of the solar wind by
cometary ions, to the existence, location and
strength of the upstream shock transition and of
(possibly) backscattered particles from the shock
and other,unexpected, plasma populations. Data
will be collected on such solar-wind phenomena as
the halo and core distributions of electrons,
variations in the flow velocity, and the He++/He+
ratio in relation to solar rotation and longitude.
The instrument consists of one sensor for electrons
and one for positive ions. As shown in Figure 3,
each sensor consists of a fan-shaped collimator, a
270deg spherical electrostatic analyzer, and a
Micro-Channel Plate (MCP) detector with five
discrete anodes. The collimator's field of view is
5deg in azimuth and 60deg in polar angle
respectively, the latter being centered
perpendicular to the spacecraft spin axis and thus
in the ecliptic plane. The 270deg spherical
analyzer has a better-defined response in
energy-angle space than a quadrispherical analyzer.
After leaving the analyzer, particles are
post-accelerated by a potential of 250 V for
electron and 2500 - 3500 V for ion analysis. A
Z-type three-stacked MCP detector is used to obtain
a saturated pulse-height distribution over a wide
dynamic range of counting rates. The anodes of
each MCP are split into five sections in order to
provide a five-point angular distribution with a
12deg resolution in the polar direction. The
output pulses from each MCP anode are amplified,
shaped and accumulated in 19-bit counters. The
contents of the counter are compressed into 8 bits
and stored temporarily in the PAM buffer memory.
The instrument's angular distribution in the
azimuthal direction, obtained by the spacecraft
spin, is 5.625deg within +/- 22.5deg of the solar
direction and 22.5deg in the remaining spin phase.
The instrument has four modes of energy scanning
(Table below). In each mode the energy is scanned
in steps as E(n)=30 exp (0.0066n), where E(n) is
the energy of the n-th step and n=n(1), . . . .
.,n(2). Details of the energy scanning, which is
synchronized to the spin phase, are shown for the
E1-mode in Figure 5. During each spacecraft spin
four energy steps are scanned periodically in every
22.5deg interval, i.e. the step is changed every
1.40625deg around the solar direction and 5.625deg
over the remaining azimuthal directions.
Consequently, it takes 24 spacecraft spins in the
E1-mode to cover the complete energy range in 96
steps.
At high bit rate (2048 bit/s), three-dimensional
velocity distributions will be obtained for both
electrons and ions. These data, produced during
one spin, will be transmitted in 10 PCM frames (5
s) during the next spin interval. At low bit rate
(64 bit/s), two-dimensional distributions will be
obtained for electrons and ions by summing the
counts from each anode. The energy scanning will
be carried out over 16 spin periods once every 512
s, required to transmit these data.
The ESP instrument will be operated during the
Halley-encounter phase as well as during the cruise
and post-encounter phases, but only while Planet-A
is in its high-spin-rate mode (nominally 6.3 rpm).
-----------------------------------------------------------------------
Table 2. Energy scanning modes of Planet-A Solar-Wind Plasma Experiment
Time for one
Total no. complete
Mode n(1) n(2) delta n of steps Energy range (eV) sequence* (s)
-----------------------------------------------------------------------
E1 0 95 1 96 30 ~ 15800 228.6
E2 O 63 1 64 30 ~ 1920 152.4
E3 32 95 1 64 250 ~ 15800 152.4
E4 1 95 2 48 34 ~ 15800 114.3
-----------------------------------------------------------------------
n(1) = lowest step number delta n = step interval
n(2) = highest step number * = times refer to high bit rate;
always 512 s at low bit rate"
END_OBJECT = INSTRUMENT_INFORMATION
OBJECT = INSTRUMENT_REFERENCE_INFO
REFERENCE_KEY_ID = "ESA-SP1066"
END_OBJECT = INSTRUMENT_REFERENCE_INFO
OBJECT = INSTRUMENT_REFERENCE_INFO
REFERENCE_KEY_ID = "NATURE321"
END_OBJECT = INSTRUMENT_REFERENCE_INFO
END_OBJECT = INSTRUMENT
END
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