The Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) will answer important questions posed by the mission's main objectives. After Giotto, this will be the first time the volatile part of a comet will be analyzed in situ. This is a very important investigation, as comets, in contrast to meteorites, have maintained most of the volatiles of the solar nebula. To accomplish the very demanding objectives through all the different phases of the comet's activity, ROSINA has unprecedented capabilities including very wide mass range (1 to >300 amu), very high mass resolution (m/Δ m > 3000, i.e. the ability to resolve CO from N2 and 13C from 12CH), very wide dynamic range and high sensitivity, as well as the ability to determine cometary gas velocities, and temperature. ROSINA consists of two mass spectrometers for neutrals and primary ions with complementary capabilities and a pressure sensor. To ensure that absolute gas densities can be determined, each mass spectrometer carries a reservoir of a calibrated gas mixture allowing in-flight calibration. Furthermore, identical flight-spares of all three sensors will serve for detailed analysis of all relevant parameters, in particular the sensitivities for complex organic molecules and their fragmentation patterns in our electron bombardment ion sources
1978), A technique to determine the charge state of anomalous low-energy cosmic rays, in 15th International Cos-(1996), New high temporal and spatial resolution measurements by SAMPEX of the precipitation of relativistic electrons,
Acceleration of interstellar pickup H+ and He+ as well as of solar wind protons and alpha particles has been observed on Ulysses during the passage of a corotating interaction region (CIR) at ∼4.5 AU. Injection efficiencies for both the high thermal speed interstellar pickup ions (H+ and He+) and the low thermal speed solar wind ions (H+ and He++) are derived using velocity distribution functions of protons, pickup He+ and alpha particles from < 1 to 60 keV/e and of ions (principally protons) above ∼60 keV. The observed spatial variations of the few keV and the few hundred keV accelerated pickup protons across the forward shock of the CIR indicate a two stage acceleration mechanism. Thermal ions are first accelerated to speeds of 3 to 4 times the solar wind speed inside the CIR, presumably by some statistical mechanism, before reaching higher energies by a shock acceleration process. Our results also indicate that (1) the injection efficiencies for pickup ions are almost 100 times higher than they are for solar wind ions, (2) pickup H+ and He+ are the two most abundant suprathermal ion species and they carry a large fraction of the particle thermal pressure, (3) the injection efficiency is highest for protons, lowest for He+, and intermediate for alpha particles, (4) both H+ and He+ have identical spectral shapes above the cutoff speed for pickup ions, and (5) the solar wind frame velocity distribution function of protons has the form F(w) = F0w−4 for 1 < w < ∼5, where w is the ion speed divided by the solar wind speed. Above w ∼ 5‐10 the proton spectrum becomes steeper. These results have important implications concerning acceleration of ions by shocks and CIRs, acceleration of anomalous cosmic rays, and particle dynamics in the outer heliosphere.
Abstract. Observations of the composition of inner source pickup ions in the solar wind, from the Solar Wind Ion Composition Spectrometer on Ulysses, are presented. The composition is similar to that of the solar wind and, in particular, contains volatile elements such as neon. These observations suggest strongly, and perhaps conclusively, that inner source pickup ions result from solar wind particles that are embedded in dust grains and then released. Our observations also suggest that inner source pickup ions may be an important source for particles accelerated at shocks surrounding corotating interaction regions since the resulting composition will resemble that of the solar wind, as is observed. Mechanisms are described whereby inner source pickup ions can be preferentially injected into the shock acceleration mechanism.
Abstract. We have measured H +, He ++, and He + distribution functions over the solar wind through the suprathermal energy range during two corotating interaction region (CIR) events observed by the STICS, MASS, and STEP instruments on board the Wind spacecraft at 1 AU during April and May 1995. The major properties we find are as follows: In the suprathermal energy range (-10-500 keV/nucleon), the particle intensities peak inside the CIR itself, in the compressed and decelerated fast solar wind, in contrast to the situation at MeV energies, where the peak inten- (1) Suprathermal CIR ions at 1 AU originated close (within -0.5 AU) to the point of observation, not in the outer heliosphere; (2) the injection/acceleration mechanism is not especially sensitive to charge-to-mass ratio over the range 0.25-1.0; (3) since the particles are locally accelerated, the low-energy ion populations we observe contain the seed population; (4) the bulk solar wind itself is not the source of the energetic ions; rather, the source is in the suprathermal tail, with an injection threshold in the spacecraft frame of-1.8-2.5 times the solar wind speed; and (5) in at least one of these CIRs, suprathermal particle acceleration is not shock associated and must therefore be associated with a statistical mechanism or compression in the solar wind.
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