| 1. |
- Björn, Lars Olof, et al.
(författare)
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Evolution of UV-B regulation and protection in plants
- 2002
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Ingår i: Advances in Space Research. - 1879-1948 .- 0273-1177. ; 30:6, s. 1557-1562
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Konferensbidrag (refereegranskat)abstract
- Plants have evolved under the influence of UV-B radiation and have acquired systems for monitoring it and investing appropriate resources for protection against it, i.e., filters, quenchers of radicals and reactive oxygen species, and repair systems. An hypothesis for how plants monitor radiation has been presented.
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| 2. |
- Bohm, Martin, et al.
(författare)
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Dynamic trapping of electrons in the porcupine ionospheric ion beam experiment
- 1992
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Ingår i: Advances in Space Research. - 0273-1177. ; 12, s. 9-14
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Tidskriftsartikel (refereegranskat)abstract
- Electrons are needed to maintain quasineutrality in a case where positive ions are injected across the magnetic field into a limited volume in a magnetized plasma. In the absence of collisions, a positive potential builds up and traps the electrons which enter the region along the magnetic field. If the added density of ions exceeds the ambient density, large potential differences along the magnetic field can be maintained this way. The process explains several features of the Porcupine xenon ion beam injection experiment, where strong magnetic-field-aligned electric fields were measured in the vicinity of a xenon ion beam which was injected into the ambient ionosphere from a spinning subpayload. © 1992.
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| 3. |
- Brenning, Nils, et al.
(författare)
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Critical ionization velocity interaction in the CRIT I rocket experiment
- 1990
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177. ; 10, s. 63-66
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Tidskriftsartikel (refereegranskat)abstract
- In the rocket experiment CRIT I, launched from Wallops Island on 13 May 1986, two identical Barium shaped charges were fired from distances of 1.3 km and 3.6 km towards the main experiment payload, which was separated from a sub-payload by a couple of km along the magnetic field. The relevance of earlier proposed mechanisms for electron heating in ionospheric critical velocity experiments is investigated in the light of the CRIT I results. It is concluded that both the "homogeneous" and the "ionizing front" models can be applied, in different parts of the stream. It is also possible that a third, entirely different, mechanism may contribute to the electron heating. This mechanism involves direct energization of electrons in the magnetic-field-aligned component of the DC electric field. © 1989.
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| 4. |
- Brenning, Nils, et al.
(författare)
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Electrodynamic interaction between the CRIT I ionized barium streams and the ambient ionosphere
- 1990
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177. ; 10, s. 67-70
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Tidskriftsartikel (refereegranskat)abstract
- In the CRIT I Critical Velocity experiment, launched from Wallops Island on 13 May, 1986, two fast barium streams were ejected by means of shaped charges. Their electrodynamic interaction with the ambient ionosphere is discussed. An outstanding feature of the DC electric field observed within the streams was a large magnetic-field-aligned component, persisting on the time scale of the passage of the streams. One interpretation of the DC electric field data is that the internal electric fields of the streams is not greatly modified by Birkeland currents, i.e. a state is established, where the transverse currents are to a first approximation divergence-free. It is argued that this interpretation can explain why a reversal of the strong explosion-directed electric field was observed in the first explosion but not in the second (more distant one). © 1989.
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| 5. |
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| 6. |
- Fälthammar, Carl-Gunne
(författare)
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Electric fields in the magnetosphere
- 1982
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177. ; 2, s. 19-23
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Tidskriftsartikel (refereegranskat)
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| 7. |
- Ivchenko, Nickolay V., et al.
(författare)
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Current singularities observed on Astrid-2
- 2002
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Ingår i: Advances in Space Research. - 0273-1177 .- 1879-1948. ; 30:7, s. 1779-1782
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Tidskriftsartikel (refereegranskat)abstract
- Swedish microsatellite Astrid-2 carried out,electric and magnetic field measurements at 1000 km altitude during its operation in January-July, 1999. At a number of occasions sharp gradients in the magnetic field were observed by the satellite. If interpreted as spatial gradients they imply current densities of hundreds muA/m(2). Occurrence of such 11 current singularities is studied. The nature of the events is discussed.
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| 8. |
- Rothwell, P.L., et al.
(författare)
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Substorm breakup on closed field lines
- 1988
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177. ; 8, s. 347-350
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Tidskriftsartikel (refereegranskat)abstract
- This model explains why breakup has been observed as low as L = 5-6 and predicts that a higher concentration of O+ in the plasma sheet will permit breakup at such low L values. It is argued that the establishment of a coupled current structure within a single arc leads to a quasi-stable system i.e. the pre-breakup regime. Perturbation of the pre-breakup structure leads to an instability criterion. Certain quiescent configurations are inherently unstable. Thus transitions from a stable to an unstable situation can trigger a rapid poleward expansion of the quiescent arc or substorm breakup. In our model the kinetic energy of injected plasma from the magnetotail supplies the energy for breakup. © 1989.
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| 9. |
- Aartsen, M. G., et al.
(författare)
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Astrophysical neutrinos and cosmic rays observed by IceCube
- 2018
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 62:10, s. 2902-2930
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Tidskriftsartikel (refereegranskat)abstract
- The core mission of the IceCube neutrino observatory is to study the origin and propagation of cosmic rays. IceCube, with its surface component IceTop, observes multiple signatures to accomplish this mission. Most important are the astrophysical neutrinos that are produced in interactions of cosmic rays, close to their sources and in interstellar space. IceCube is the first instrument that measures the properties of this astrophysical neutrino flux and constrains its origin. In addition, the spectrum, composition, and anisotropy of the local cosmic-ray flux are obtained from measurements of atmospheric muons and showers. Here we provide an overview of recent findings from the analysis of IceCube data, and their implications to our understanding of cosmic rays.
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| 10. |
- Adriani, O., et al.
(författare)
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Measurements of cosmic-ray proton and helium spectra with the PAMELA calorimeter
- 2013
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 51:2, s. 219-226
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Tidskriftsartikel (refereegranskat)abstract
- We present a new measurement of the cosmic ray proton and helium spectra by the PAMELA experiment performed using the "thin" (in terms of nuclei interactions) sampling electromagnetic calorimeter. The described method, optimized by using Monte Carlo simulation, beam test and experimental data, allows the spectra to be measured up to 10 TeV, thus extending the PAMELA observational range based on the magnetic spectrometer measurement.
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