Voyager Plasma Science Instrument

2015

The solar wind is a supersonic flow of magnetized plasma. It is time-dependent on all scales and expands with distance. The flow has fluctuations on a broad range of scales and frequencies. This fluctuations are not just convected outward but show energy cascades among the different scales. The solar wind turbulence peculiar phenomenology has been comprehensively reviewed by Tu and Marsch [11] and Bruno and Carbone [2]. As the distance from the sun increases, the available data on plasma and magnetic field become increasingly scarce. At distance of the order of 1 astronomic unit (AU), several measurement have been performed by various crafts, but, nowadays, only the Voyager spacecrafts can measure data in the heliosheath, the outermost layer in heliosphere where the solar wind is slowed by the pressure of the interstellar gas, and only the Voyager 2 craft can measure both plasma and magnetic fields (Voyager 1 can measure only the magnetic field, and Pioneer 10 and 11 has ceased comm...

Cosmic Research, 2013

Design of the plasma spectrometer BMSW (Fast Monitor of the Solar Wind, possessing high tem poral resolution) is described in the paper, as well as its characteristics and modes of operation. Some exam ples of measurements of various properties of the solar wind, made with this instrument installed onboard the high apogee satellite Spektr R, are presented.

Czechoslovak Journal of Physics, 1985

The paper describes a method of fast serial measurements and data processing of the energy distribution function of solar wind ions. The method was applied on the Prognoz 8 Satellite as part of the MONITOR experiment. In this experiment the electrostatic energy analysers for ions with energies ranging from 0" 16 to 4.2 keV and a three-collector Faraday cup to measure the total ion flux of the solar wind and its arrival angle were used. The distribution function measurements were ruade with high time resolution of about 1 sec. The measurements show that considerable deformations of the distribution function take place in a shock wave and magnetosheath in time intervals comparable with the period of measurement. The form of the energy spectra measured may be explained in some measurements by the simultaneous existence of several fluxes of charged particles with different directions and velocities.

Space Science Reviews

This instrument is designed to make measurements of the full three-dimensional distribution of suprathermal electrons and ions from solar wind plasma to low energy cosmic rays, with high sensitivity, wide dynamic range, good energy and angular resolution, and high time resolution. The primary scientific goals are to explore the suprathermal particle population between the solar wind and low energy cosmic rays, to study particle accleration and transport and wave-particle interactions, and to monitor particle input to and output from the Earth's magnetosphere.Three arrays, each consisting of a pair of double-ended semi-conductor telescopes each with two or three closely sandwiched passivated ion implanted silicon detectors, measure electrons and ions above 20 keV. One side of each telescope is covered with a thin foil which absorbs ions below 400 keV, while on the other side the incoming 1 MeV) and ions (up to 11 MeV) are identified by the two double-ended telescopes which have a...

Journal of Geophysical Research, 1998

The proton monitor, a small subsensor in the Charge, Element, and Isotope Analysis System/Mass Time-of-Flight (CELIAS/MTOF) experiment on the SOHO spacecraft, was designed to assist in the interpretation of measurements from the high mass resolution main MTOF sensor. In this paper we demonstrate that the proton monitor data may be used to generate reasonably accurate values of the solar wind proton bulk speed, density, thermal speed, and north/south flow direction. Correlation coefficients based on comparison with the solar wind measurements from the SWE instrument on the Wind spacecraft range from 0.87 to 0.99. On the basis of the initial 12 months of observations, we find that the proton momentum flux is almost invariant with respect to the bulk speed, confirming a previously published result. We present observations of two interplanetary shock events, and of an unusual solar wind density depletion. This large density depletion, and the correspondingly large drop in the solar wind ram pressure, may have been the cause of a nearly simultaneous large increase in the flux of relativistic magnetospheric electrons observed at geosynchronous altitudes by the GOES 9 spacecraft. Extending our data set with a 10-year time span from the OMNIWeb data set, we find an average frequency of about one large density depletion per year. The origin of these events is unclear; of the 10 events identified, 3 appear to be corotating and at least 2 are probably CME related. The rapidly available, comprehensive data coverage from SOHO allows the production of near-real time solar wind parameters that are now accessible on the World Wide Web. 17,205 17,206 IPAVICH ET AL.: SOLAR WIND PROTON MONITOR

Advances in Space Research, 1996

The initial acceleration of the nonspherically symmetric solar wind is discussed according to recent treatments via nonspherically symmetric and nonpolytropic MHD models. These studies give some physical quantities of the plasma outflow which the proposed Solar Probe mission could measure. For example, among the predictions of such twodimensional models is that as one approaches the sun the spatially extended heating and temperature increase while as the polar axis is approached, the outflow speed increases, although the plasma density and pressure decrease. The sonic transition is closer to the Sun in streamlines closer to the solar rotation axis than it is for streamlines further away and closer to the ecliptic plane. Preliminary observations from the Ulysses spacecraft at several AU suggesting a latitudinal gradient of ,< 5 km s-'deg-l from a major high speed stream over the latitudinal range up to 55 deg at ,> 3.5 AU, are in agreement with such models. Thus, since most measurements of the solar wind parameters have taken place to this date on the ecliptic plane and at distances larger than ,> 100 r,?, a comparison of the data of the Solar Probe mission with such theories shall be of co&derable interest for a deeper understanding of the initial acceleration of the closer astrophysical outflow of the solar wind with profound implications as well for other more distant and similar cosmic phenomena.

Space Science Reviews, 1992

The plasma instrumentation (PLS) for the Galileo Mission comprises a nested set of four spherical-plate electrostatic analyzers and three miniature, magnetic mass spectrometers. The three-dimensional velocity distributions of positive ions and electrons, separately, are determined for the energy-per-unit charge (E/Q) range of 0.9 V to 52 kV. A large fraction of the 47 pisteradian solid angle for charged particle velocity vectors is sampled by means of the fan-shaped field-of-view of 160 deg, multiple sensors, and the rotation of the spacecraft spinning section. The fields-of-view of the three mass spectrometers are respectively directed perpendicular and nearly parallel and anti-parallel to the spin axis of the spacecraft. These mass spectrometers are used to identify the composition of the positive ion plasmas, e.g., H + , O + , Na + , and S + , in the Jovian magnetosphere. The energy range of these three mass spectrometers is dependent upon the species. The maximum temporal resolutions of the instrument for determining the energy (E/Q) spectra of charged particles and mass (M/Q) composition of positive ion plasmas are 0.5 s. Three-dimensional velocity distributions of electrons and positive ions require a minimum sampling time of 20 s, which is slightly longer than the spacecraft rotation period. The two instrument microprocessors provide the capability of inflight implementation of operational modes by ground-command that are tailored for specific plasma regimes, e.g., magnetosheath, plasma sheet, cold and hot torus, and satellite wakes, and that can be improved upon as acquired knowledge increases during the tour of the Jovian magnetosphere. Because the instrument is specifically designed for measurements in the environs of Jupiter with the advantages of previous surveys with the Voyager spacecraft, first determinations of many plasma phenomena can be expected. These observational objectives include field-aligned currents, three-dimensional ion bulk flows, pickup ions from the Galilean satellites, the spatial distribution of plasmas throughout most of the magnetosphere and including the magnetotail, and ion and electron flows to and from the Jovian ionosphere.

The Astrophysical Journal, 2009

This paper describes the principal features of 24 hr averages of the magnetic field strength variations B (t) and their relationships to the plasma and energetic particles observed prior to and after the crossing of the termination shock (TS) by Voyager 2 (V2). The solar wind (pre-TS crossing) and heliosheath (post-TS crossing) data extend from day of year (DOY) 1 through 241, 2007 and from 2007 DOY 245 through 2008 DOY 80, respectively. In the solar wind, two merged interaction regions (MIRs) were observed in which the ratio of plasma pressure to magnetic pressure in the solar wind was relatively low. Strong magnetic fields and low values of beta were also observed just prior to its crossing of the TS. The predicted correlation between peaks in the intensity of energetic particles in the solar wind when V2 crossed the heliospheric current sheet from positive to negative magnetic polarity in the solar wind was not observed. In the heliosheath, V2 observed a feature characterized by large enhancements of the density N and the proton temperature T, a small increase in speed V, and a depression in B. The distributions of 24 hr averages of B and beta were approximately log-normal in both the solar wind and the heliosheath. A unipolar region was observed for 73 days in the heliosheath, as the heliospheric current sheet moved toward the equatorial plane to latitudes lower than V2.

Space Science Reviews, 2016

NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.

Journal of Geophysical Research, 2006