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  • 1
    Electronic Resource
    Electronic Resource
    Magnetospheric plasma analyzer for spacecraft with constrained resources (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 1026-1033 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A light-weight, low-power, plasma analyzer is described that can be used for measuring the plasma environments of spacecraft with constrained resources. A unique system using a single electrostatic analyzer coupled to a single array of channel electron multipliers allows measurement of the three-dimensional energy per charge distributions of both ions and electrons over E/q ranges from ∼1 eV/q to (approximately-greater-than)40 keV/q. Particles selected by the analyzer are post-accelerated into the multipliers to maintain sensitivity for the lowest energy particles. An instrument using this concept called the magnetospheric plasma analyzer (MPA) is described. Presently, three MPAs are in geosynchronous orbits (GEO) aboard spacecraft with International Designators of 1989-046, 1990-095, and 1991-080. The MPA and its response characteristics are described, and examples of on-orbit data showing some of the MPA capabilities are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1144173
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  • 2
    Electronic Resource
    Electronic Resource
    Channel electron multiplier compatibility with Viton and Apiezon-L vacuum grease (1987)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 58 (1987), S. 2331-2332 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Clean Viton and Viton coated with Apiezon-L vacuum grease were tested for their noncontaminating compatibility with channel electron multipliers (CEMs). The test setup and procedure were the same as those used previously in conjunction with CEM compatibility tests of certain epoxies, solder, and fluorocarbon polymer materials useful for construction of spaceflight sensors. While some CEM gain degradation was noted during exposure to Viton and Apiezon-L, the present tests indicate that, at least over instrument lifetimes of ∼2×1012 counts, these materials should be suitable for (1) preflight space sensor testing systems, (2) hermetic seals for CEM-based space sensors, and (3) terrestrial CEM-based instrumentation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139346
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Diagnostics of space plasmas (invited) (1986)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 1711-1716 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Diverse plasmas have been observed in the magnetospheres of Earth and other planets, and in interplanetary space. Recently, measurements were made by a space probe at Comet Giacobini–Zinner. In these various plasma regimes investigated during the space era, plasma characteristics vary widely: particle densities range from 〈0.01 to 1000 per cc, energies from 〈1 eV to many MeV, temperatures from 〈1 eV to 〉1000 eV, and bulk flow speeds from near stationary to 〉1000 km/s. A variety of plasma-wave activity and instabilities characterize these plasmas. The measurements are made with several different generic types of instruments including electrostatic analyzers and systems which combine electrostatic analysis with time-of-flight or magnetic analysis in order to identify ions and their charge states. This paper outlines the plasma regimes found in space, discusses instrument design principles and constraints imposed by limited spacecraft resources, describes a few instruments, and highlights a small selection of scientific results derived from diagnostics of space plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1138558
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  • 4
    Electronic Resource
    Electronic Resource
    2π-radian field-of-view toroidal electrostatic analyzer (1988)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 59 (1988), S. 743-751 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: We describe a new type of electrostatic charged particle analyzer based on toroidal geometry. The analyzer features a 360°×10° (polar×azimuthal) field of view and a focal length in the polar direction significantly longer than that of similar devices based on spherical geometry. Extended focal length is a requirement for matching the electrostatic energy spectrometer with a second, mass-resolving, analyzer. Laboratory tests show that the toroid design has a large geometric factor per unit of instrument weight, good energy-angle resolution in the particle deflection plane, and sharp (1.0° FWHM) resolution at focus in the polar angle direction. The analyzer is well suited for use in satellite-borne mass spectrometry and also as a stand-alone electrostatic analyzer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1139821
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Plasma acceleration at the Earth's magnetopause: evidence for reconnection (1979)
    [s.l.] : Nature Publishing Group
    Nature 282 (1979), S. 243-246 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A characteristic of magnetic field reconnection is the acceleration of plasma as it flows across a rotational discontinuity. At the Earth's magnetopause this effect has only been observed recently during a few magnetopause crossings by the ISEE satellites. For one example analysed in detail ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/282243a0
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  • 6
    Electronic Resource
    Electronic Resource
    Abundance differences in solar wind double streams (1974)
    Springer
    Solar physics 37 (1974), S. 451-467 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Eight examples of persistent double ion streams with simultaneously resolved protons and alpha particles have been found in the 1971 and 1972 data from the Los Alamos plasma analyzer on IMP 6. The proton streams are observed to have greater velocity separations than their alpha particle counterparts and the secondary stream is the higher velocity stream in each of these examples. Helium to hydrogen abundance ratios for the two streams observed simultaneously differ by up to a factor of ∼ 4; the average is 2.3. The secondary, higher velocity stream usually has the larger fraction of helium. Selection criteria may bias these results to some degree. Observations of double streams at 1 AU with large abundance differences in the separate streams provide evidence that their origin is in a corona with an inhomogeneous distribution of helium, although the evidence may not be considered conclusive at present. Several conceptual models are suggested for the formation of double streams which account for these abundance differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152503
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  • 7
    Electronic Resource
    Electronic Resource
    Solar wind heavy ion abundances (1975)
    Springer
    Solar physics 43 (1975), S. 463-473 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract During periods in 1969–1971 when interplanetary flow conditions were quiet, 17 determinations of the solar wind Fe and Si abundances and 7 of the O abundance were made. On the average 〈N(Fe)/N(H)〉 = 5.3 × 10-5, 〈N(Si)/N(H)〉 = 7.6 × 10-5 and 〈N(O)/N(H)〉 = 5.2 × 10-4. Variations from the averages over a total range of factors of ∼4 for O, ∼4 for Si, and ∼ 10 for Fe have have observed. Although Fe and Si abundance variations appear to be correlated, no other element correlation pairs are unambiguously discernible from the present data set.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152368
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  • 8
    Electronic Resource
    Electronic Resource
    Helium abundance variations in the solar wind (1983)
    Springer
    Solar physics 83 (1983), S. 367-378 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Helium abundance variations in the solar wind have been studied using data obtained with Los Alamos plasma instrumentation on IMP 6, 7, and 8 from 1971 through 1978. For the first time, average flow characteristics have been determined as a function of helium abundance, A(He). Low and average values of A(He) are each preferentially identified with a different characteristic plasma ‘state’ these correspond to what have previously been recognized as the signatures of interplanetary magnetic field polarity reversals and high speed streams, respectively. Helium enhancements at 1 AU also can be identified with a characteristic plasma state, which includes high magnetic field intensity and low proton temperature. This is further evidence that such enhancements are a signal of coronal transient mass ejections. Long-term averages of A(He) at least partially reflect the relative frequency with which coronal streamers, holes, and transients extend their influence into the ecliptic plane at 1 AU. As a result, there is a real and pronounced solar cycle variation of solar wind H(He).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148286
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  • 9
    Electronic Resource
    Electronic Resource
    Solar flares and solar wind helium enrichments: July 1965–July 1967 (1972)
    Springer
    Solar physics 23 (1972), S. 467-486 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It has previously been suggested that the very high relative abundances of helium occasionally observed in the solar wind mark the plasma accelerated by major solar flares. To confirm this hypothesis, we have studied the 43 spectra with He/H ⩾ 15% that were observed among 10300 spectra collected by Vela 3 between July 1965–July 1967. The 43 spectra were distributed among 16 distinct periods of helium enhancement, 12 of which (containing 75% of the spectra) were associated with solar flares. Six new flare-enhancement events are discussed in this paper. It is concluded that the association of helium enhancements with major flares is real, non-random and very strong. With this study, there are 12 cases of reliable associations between helium enhancements (He/H ⩾ 15%) and flares reported in the literature. The general characteristics of these events are discussed. It is found that the flares are typically large and bright (2B or 3B), often they produce cosmic ray protons, and they are widely distributed in solar longitude. The average transit velocity of the pistons (i.e., flare accelerated driver gas) is in excellent agreement with earlier observations of flare shock velocities. The degree to which the pistons have been slowed in transit is in good agreement with theory. The average percentage of helium in the enhanced regions is 15%, but this number should not be considered more than an extremely rough estimate because of very arbitrary decisions that had to be made as to when we would consider an ‘enhancement’ had ended. The number of positively charged particles in the enhanced region is estimated to be of the order of 4 × 1039. A qualitative discussion of some of the possibilities for the source of helium enhanced plasma is presented. It is suggested that the helium enriched plasma may be the piston producing the shock causing the Type II radio emission. The size of the Type II emission region and the number of particles in the helium enhancement permit an estimate to be made of the density of the corona at the origin of the piston. From this it is estimated further that the piston must come from below about 0.5 R ⊙, in agreement with the 0.2–0.3 R ⊙ often given for the initial height of the Type II emission source. Recent theoretical discussions have indicated that the corona as a whole can be expected to show helium enrichments at these levels. It is pointed out that observations of solar wind helium enhancement can be expected to be a useful tool in studying the distribution and relative abundance of helium in different layers of the solar corona, as well as mechanisms for the acceleration of plasma by solar flares.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00148109
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  • 10
    Electronic Resource
    Electronic Resource
    A pictorial comparison of interplanetary magnetic field polarity, solar wind speed, and geomagnetic disturbance index during the sunspot cycle (1977)
    Springer
    Solar physics 52 (1977), S. 485-495 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of interplanetary magnetic field polarity, solar wind speed, and geomagnetic disturbance index (C9) during the years 1962–1975 are compared in a 27-day pictorial format that emphasizes their associated variations during the sunspot cycle. This display accentuates graphically several recently reported features of solar wind streams including the fact that the streams were faster, wider, and longer-lived during 1962–1964 and 1973–1975 in the declining phase of the sunspot cycle than during intervening years (Bame et al., 1976; Gosling et al., 1976). The display reveals strikingly that these high-speed streams were associated with the major, recurrent patterns of geomagnetic activity that are characteristic of the declining phase of the sunspot cycle. Finally, the display shows that during 1962–1975 the association between long-lived solar wind streams and recurrent geomagnetic disturbances was modulated by the annual variation (Burch, 1973) of the response of the geomagnetic field to solar wind conditions. The phase of this annual variation depends on the polarity of the interplanetary magnetic field in the sense that negative sectors of the interplanetary field have their greatest geomagnetic effect in northern hemisphere spring, and positive sectors have their greatest effect in the fall. During 1965–1972 when the solar wind streams were relatively slow (500 km s-1), the annual variation strongly influenced the visibility of the corresponding geomagnetic disturbance patterns.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149663
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