The BEAN experiment - An EISCAT study of ion temperature anisotropies
Results are presented from a novel EISCAT special programme, SP-UK-BEAN, intended for the direct measurement of the ion temperature anisotropy during ion frictional heating events in the high-latitude F-region. The experiment employs a geometry which provides three simultaneous estimates of the ion...
Published in: | Annales Geophysicae |
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Springer Verlag
1995
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00038016 2023-05-15T16:04:32+02:00 The BEAN experiment - An EISCAT study of ion temperature anisotropies McCrea, I. W. Jones, G. O. L. Lester, M. 1995-02 electronic https://doi.org/10.1007/s00585-995-0177-x https://noa.gwlb.de/receive/cop_mods_00038016 eng eng Springer Verlag Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.1007/s00585-995-0177-x https://noa.gwlb.de/receive/cop_mods_00038016 https://open-access.net/ uneingeschränkt info:eu-repo/semantics/restrictedAccess article Verlagsveröffentlichung article Text doc-type:article 1995 ftnonlinearchiv https://doi.org/10.1007/s00585-995-0177-x 2022-02-08T22:43:15Z Results are presented from a novel EISCAT special programme, SP-UK-BEAN, intended for the direct measurement of the ion temperature anisotropy during ion frictional heating events in the high-latitude F-region. The experiment employs a geometry which provides three simultaneous estimates of the ion temperature in a single F-region observing volume at a range of aspect angles from 0° to 36°. In contrast to most previous EISCAT experiments to study ion temperature anisotropies, field-aligned observations are made using the Sodankylä radar, while the Kiruna radar measures at an aspect angle of the order of 30°. Anisotropic effects can thus be studied within a small common volume whose size and altitude range is limited by the radar beamwidth, rather than in volumes which overlap but cover different altitudes. The derivation of line-of-sight ion temperature is made more complex by the presence of an unknown percentage of atomic and molecular ions at the observing altitude and the possibility of non-Maxwellian distortion of the ion thermal velocity distribution. The first problem has been partly accounted for by insisting that a constant value of electron temperature be maintained. This enables an estimate of the ion composition to be made, and facilitates the derivation of more realistic line-of-sight ion temperatures and temperature anisotropies. The latter problem has been addressed by assuming that the thermal velocity distribution remains bi-Maxwellian. The limitations of these approaches are discussed. The ion temperature anisotropies and temperature partition coefficients during two ion heating events give values intermediate between those expected for atomic and for molecular species. This result is consistent with an analysis which indicates that significant proportions of molecular ions (up to 50%) were present at the times of greatest heating. Article in Journal/Newspaper EISCAT Kiruna Sodankylä Niedersächsisches Online-Archiv NOA Kiruna Sodankylä ENVELOPE(26.600,26.600,67.417,67.417) Annales Geophysicae 13 2 177 188 |
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language |
English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung McCrea, I. W. Jones, G. O. L. Lester, M. The BEAN experiment - An EISCAT study of ion temperature anisotropies |
topic_facet |
article Verlagsveröffentlichung |
description |
Results are presented from a novel EISCAT special programme, SP-UK-BEAN, intended for the direct measurement of the ion temperature anisotropy during ion frictional heating events in the high-latitude F-region. The experiment employs a geometry which provides three simultaneous estimates of the ion temperature in a single F-region observing volume at a range of aspect angles from 0° to 36°. In contrast to most previous EISCAT experiments to study ion temperature anisotropies, field-aligned observations are made using the Sodankylä radar, while the Kiruna radar measures at an aspect angle of the order of 30°. Anisotropic effects can thus be studied within a small common volume whose size and altitude range is limited by the radar beamwidth, rather than in volumes which overlap but cover different altitudes. The derivation of line-of-sight ion temperature is made more complex by the presence of an unknown percentage of atomic and molecular ions at the observing altitude and the possibility of non-Maxwellian distortion of the ion thermal velocity distribution. The first problem has been partly accounted for by insisting that a constant value of electron temperature be maintained. This enables an estimate of the ion composition to be made, and facilitates the derivation of more realistic line-of-sight ion temperatures and temperature anisotropies. The latter problem has been addressed by assuming that the thermal velocity distribution remains bi-Maxwellian. The limitations of these approaches are discussed. The ion temperature anisotropies and temperature partition coefficients during two ion heating events give values intermediate between those expected for atomic and for molecular species. This result is consistent with an analysis which indicates that significant proportions of molecular ions (up to 50%) were present at the times of greatest heating. |
format |
Article in Journal/Newspaper |
author |
McCrea, I. W. Jones, G. O. L. Lester, M. |
author_facet |
McCrea, I. W. Jones, G. O. L. Lester, M. |
author_sort |
McCrea, I. W. |
title |
The BEAN experiment - An EISCAT study of ion temperature anisotropies |
title_short |
The BEAN experiment - An EISCAT study of ion temperature anisotropies |
title_full |
The BEAN experiment - An EISCAT study of ion temperature anisotropies |
title_fullStr |
The BEAN experiment - An EISCAT study of ion temperature anisotropies |
title_full_unstemmed |
The BEAN experiment - An EISCAT study of ion temperature anisotropies |
title_sort |
bean experiment - an eiscat study of ion temperature anisotropies |
publisher |
Springer Verlag |
publishDate |
1995 |
url |
https://doi.org/10.1007/s00585-995-0177-x https://noa.gwlb.de/receive/cop_mods_00038016 |
long_lat |
ENVELOPE(26.600,26.600,67.417,67.417) |
geographic |
Kiruna Sodankylä |
geographic_facet |
Kiruna Sodankylä |
genre |
EISCAT Kiruna Sodankylä |
genre_facet |
EISCAT Kiruna Sodankylä |
op_relation |
Annales Geophysicae -- http://www.bibliothek.uni-regensburg.de/ezeit/?1458425 -- https://www.ann-geophys.net/ -- https://www.ann-geophys.net/volumes.html -- http://link.springer.com/journal/585 -- 1432-0576 https://doi.org/10.1007/s00585-995-0177-x https://noa.gwlb.de/receive/cop_mods_00038016 |
op_rights |
https://open-access.net/ uneingeschränkt info:eu-repo/semantics/restrictedAccess |
op_doi |
https://doi.org/10.1007/s00585-995-0177-x |
container_title |
Annales Geophysicae |
container_volume |
13 |
container_issue |
2 |
container_start_page |
177 |
op_container_end_page |
188 |
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1766400112086482944 |