Origin of energetic ions in the polar cusp inferred from ion composition measurements by the Viking satellite

1995 ◽  
Vol 13 (6) ◽  
pp. 595-607 ◽  
Author(s):  
G. Kremser ◽  
J. Woch ◽  
K. Mursula ◽  
P. Tanskanen ◽  
B. Wilken ◽  
...  
Keyword(s):  
Pitch Angle ◽  
Ring Current ◽  
High Energy ◽  
Boundary Region ◽  
Ion Source ◽  
Current Layer ◽  
Ion Composition ◽  
Ion Distribution ◽  
Polar Cusp ◽  
High Energy Tail

Abstract. The magnetospheric ion composition spectrometer MICS on the Swedish Viking satellite provided measurements of the ion composition in the energy range 10.1 keV/e\\leqE/Q\\leq326.0 keV/e. Data obtained during orbit 842 were used to investigate the ion distribution in the northern polar cusp and its vicinity. The satellite traversed the outer ring current, boundary region, cusp proper and plasma mantle during its poleward movement. H+ and He++ ions were encountered in all of these regions. He+ ions were present only in the ring current. The number of O+ and O++ ions was very small. Heavy high-charge state ions typical for the solar wind were observed for the first time, most of them in the poleward part of the boundary region and in the cusp proper. The H+ ions exhibited two periods with high intensities. One of them, called the BR/CP event, appeared at energies up to 50 keV. It started at the equatorward limit of the boundary region and continued into the cusp proper. Energy spectra indicate a ring current origin for the BR/CP event. Pitch angle distributions show downward streaming of H+ ions at its equatorward limit and upward streaming on the poleward side. This event is interpreted as the result of pitch angle scattering of ring current ions by fluctuations in the magnetopause current layer in combination with poleward convection. The other of the two periods with high H+ ion intensities, called the accelerated ion event, was superimposed on the BR/CP event. It was restricted to energies \\leq15 keV and occurred in the poleward part of the boundary region. This event is regarded as the high-energy tail of magnetosheath ions that were accelerated while penetrating into the magnetosphere. The cusp region thus contains ions of magnetospheric as well as of magnetosheath origin. The appearance of the ions depends, in addition to the ion source, on the magnetic field configuration and dynamic processes inside and close to the cusp.

scholarly journals Electromagnetic power of lightning superbolts from Earth to space

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J.-F. Ripoll ◽  
T. Farges ◽  
D. M. Malaspina ◽  
G. S. Cunningham ◽  
E. H. Lay ◽  
...  
Keyword(s):  
Low Frequency ◽  
Optical Emission ◽  
High Energy ◽  
Very Low Frequency ◽  
Electromagnetic Power ◽  
Power Spectral ◽  
High Energy Tail ◽  
Van Allen Probes ◽  
Long Time ◽  
Low Frequency Waves

AbstractLightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.

Structural Characteristics of Diamond-Like Carbon Films Synthesized by Different Methods

2017 ◽  
Vol 743 ◽  
pp. 112-117
Author(s):  
Alexander Zolkin ◽  
Anna Semerikova ◽  
Sergey Chepkasov ◽  
Maksim Khomyakov
Keyword(s):  
Amorphous Phase ◽  
Ion Beam ◽  
High Energy ◽  
Carbon Films ◽  
Ion Source ◽  
Ordered Structure ◽  
Deposition Technique ◽  
Cathodic Arc Deposition ◽  
Cathodic Arc ◽  
Arc Deposition

In the present study, the Raman spectra of diamond-like amorphous (a-C) and hydrogenated amorphous (a-C:H) carbon films on silicon obtained using the ion-beam methods and the pulse cathodic arc deposition technique were investigated with the aim of elucidating the relation between the hardness and structure of the films. The hardness of the samples used in the present study was 19 – 45 GPa. Hydrogenated carbon films were synthesized using END–Hall ion sources and a linear anode layer ion source (LIS) on single-crystal silicon substrates. The gas precursors were CH4 and C3H8, and the rate of the gas flow fed into the ion source was 4.4 to 10 sccm. The ion energies ranged from 150 to 600 eV. a-C films were deposited onto Si substrates using the pulse cathodic arc deposition technique. The films obtained by the pulse arc technique contained elements with an ordered structure. In the films synthesized using low- (150 eV) and high-energy (600 eV) ions beams, an amorphous phase was the major phase. The significant blurriness of the diffraction rings in the electron diffraction patterns due to a large film thickness (180 – 250 nm) did not allow distinctly observing the signals from the elements with an ordered structure against the background of an amorphous phase.

The effect of the toroidal wavenumber spectrum on the high energy tail formation during ICRH

1997 ◽  
Vol 37 (6) ◽  
pp. 719-723 ◽  
Author(s):  
J Carlsson ◽  
L.-G Eriksson ◽  
T Hellsten
Keyword(s):  
High Energy ◽  
High Energy Tail ◽  
Wavenumber Spectrum

scholarly journals Structure of the heliosheath from HSTOF energetic neutral atoms measurements

2018 ◽  
Vol 618 ◽  
pp. A26 ◽  
Author(s):  
A. Czechowski ◽  
M. Hilchenbach ◽  
K. C. Hsieh ◽  
M. Bzowski ◽  
S. Grzedzielski ◽  
...  
Keyword(s):  
Energy Range ◽  
Ecliptic Plane ◽  
High Energy ◽  
Neutral Atoms ◽  
Ion Distribution ◽  
Ion Density ◽  
Heliospheric Observatory ◽  
Energetic Neutral Atoms ◽  
Time Periods ◽  
Ecliptic Longitude

Context. From the year 1996 until now, High energy Suprathermal Time Of Flight sensor (HSTOF) on board Solar and Heliospheric Observatory (SOHO) has been measuring the heliospheric energetic neutral atoms (ENA) flux between ±17° from the ecliptic plane. At present it is the only ENA instrument with the energy range within that of Voyager LECP energetic ion measurements. The energetic ion density and thickness of the inner heliosheath along the Voyager 1 trajectory are now known, and the ENA flux in the HSTOF energy range coming from the Voyager 1 direction may be estimated. Aims. We use HSTOF ENA data and Voyager 1 energetic ion spectrum to compare the regions of the heliosheath observed by HSTOF and Voyager 1. Methods. We compared the HSTOF ENA flux data from the forward and flank sectors of the heliosphere observed in various time periods between the years 1996 and 2010 and calculated the predicted ENA flux from the Voyager 1 direction using the Voyager 1 LECP energetic ion spectrum and including the contributions of charge exchange with both neutral H and He atoms. Results. The ratio between the HSTOF ENA flux from the ecliptic longitude sector 210−300° (the LISM apex sector) for the period 1996−1997 to the estimated ENA flux from the Voyager 1 direction is ∼1.3, but decreases to ∼0.6 for the period 1996−2005 and ∼0.3 for 1998−2006. For the flank longitude sectors (120−210° and 300−30°), the ratio also tends to decrease with time from ∼0.6 for 1996−2005 to ∼0.2 for 2008−2010. We discuss implications of these results for the energetic ion distribution in the heliosheath and the structure of the heliosphere.

scholarly journals Resonant scattering of energetic electrons in the plasmasphere by monotonic whistler-mode waves artificially generated by ionospheric modification

2014 ◽  
Vol 32 (5) ◽  
pp. 507-518 ◽  
Author(s):  
S. S. Chang ◽  
B. B. Ni ◽  
J. Bortnik ◽  
C. Zhou ◽  
Z. Y. Zhao ◽  
...  
Keyword(s):  
Test Particle ◽  
Pitch Angle ◽  
Low Frequency ◽  
Resonant Scattering ◽  
High Energy ◽  
Whistler Waves ◽  
Energetic Electrons ◽  
High Energy Electrons ◽  
Angle Scattering ◽  
Vlf Waves

Abstract. Modulated high-frequency (HF) heating of the ionosphere provides a feasible means of artificially generating extremely low-frequency (ELF)/very low-frequency (VLF) whistler waves, which can leak into the inner magnetosphere and contribute to resonant interactions with high-energy electrons in the plasmasphere. By ray tracing the magnetospheric propagation of ELF/VLF emissions artificially generated at low-invariant latitudes, we evaluate the relativistic electron resonant energies along the ray paths and show that propagating artificial ELF/VLF waves can resonate with electrons from ~ 100 keV to ~ 10 MeV. We further implement test particle simulations to investigate the effects of resonant scattering of energetic electrons due to triggered monotonic/single-frequency ELF/VLF waves. The results indicate that within the period of a resonance timescale, changes in electron pitch angle and kinetic energy are stochastic, and the overall effect is cumulative, that is, the changes averaged over all test electrons increase monotonically with time. The localized rates of wave-induced pitch-angle scattering and momentum diffusion in the plasmasphere are analyzed in detail for artificially generated ELF/VLF whistlers with an observable in situ amplitude of ~ 10 pT. While the local momentum diffusion of relativistic electrons is small, with a rate of < 10−7 s−1, the local pitch-angle scattering can be intense near the loss cone with a rate of ~ 10−4 s−1. Our investigation further supports the feasibility of artificial triggering of ELF/VLF whistler waves for removal of high-energy electrons at lower L shells within the plasmasphere. Moreover, our test particle simulation results show quantitatively good agreement with quasi-linear diffusion coefficients, confirming the applicability of both methods to evaluate the resonant diffusion effect of artificial generated ELF/VLF whistlers.

Surface Modification of Electromagnetic Railgun Components

1993 ◽  
Vol 316 ◽  
Author(s):  
M. A. Otooni ◽  
A. Graf ◽  
C. Dunham ◽  
Ian Brown ◽  
Xiang Yao
Keyword(s):  
Electron Microscopy ◽  
Metal Ion ◽  
High Energy ◽  
Ion Source ◽  
Vacuum Arc ◽  
Sufficient Evidence ◽  
Wear Properties ◽  
Implantation Energy ◽  
Rutherford Back Scattering ◽  
Spark Erosion

ABSTRACTCopper and aluminum used for rail and armature materials in electromagnetic railgun systems undergo severe degradation during the EM gun operation. The extent of this degradation is especially severe in guns operated at high energy levels or designed for repeated firings. In an effort to improve surface properties of the copper rail, armature, and sabot materials, the technique of metal ion implantation using a vacuum arc ion source has been employed. Preliminary tests have been conducted to identify the best implant species to improve spark erosion resistance, scratch resistance and hardness. The implanted species included Al, Ti, Cr, Ni, Ta, Ag, and W. The implantation energy range and dose varied between 100–180 KeV and 0.4 to 2 × 1017 cm-2, respectively . Several analytical techniques were also used to assess the effect of implanted species. These included Rutherford Back Scattering (RBS), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Microhardness Measurements, Spark Erosion and Scratch Testing. It has been tentatively concluded that Ta and Ni implantation of the copper rail substantially improve wear and inhibit arc erosion. There is also sufficient evidence to indicate that implantation of the aluminum armature with Cr and Ta, involving two stages of implantation, will also improve its mechanical and wear properties.

scholarly journals Conceptual study on parasitic low-energy RI beam production with in-flight separator BigRIPS and the first stopping examination for high-energy RI beams in the parasitic gas cell

2019 ◽  
Vol 2019 (11) ◽  
Author(s):  
T Sonoda ◽  
I Katayama ◽  
M Wada ◽  
H Iimura ◽  
V Sonnenschein ◽  
...  
Keyword(s):  
High Energy ◽  
Ion Source ◽  
Low Energy ◽  
Laser Ion Source ◽  
Gas Cell ◽  
Beam Production ◽  
Expected Benefits ◽  
Conceptual Study ◽  
Ri Beam

Abstract An in-flight separator performs the important role of separating a single specific radioactive isotope (RI) beam from the thousands of RI beams produced by in-flight fission as well as projectile fragmentation. However, when looking at ``separation'' from a different viewpoint, more than 99% of simultaneously produced RI beams are just eliminated in the focal plane slits or elsewhere in the separator. In order to enhance the effective usability of the RIKEN in-flight separator BigRIPS, we have been developing an innovative method: parasitic laser ion source (PALIS), which implements parasitic low-energy RI beam production by saving eliminated RI beams during BigRIPS experiments. In this paper, we present the expected benefits and feasibility for the PALIS concept and the results of the first stopping examination for high-energy RI beams in the gas cell.

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