NON-TH • PIASMA OBSERVATIONS USING EISCAT: ASPECT ANGLE DEP]•ID•NCE
Abstract. Recent observations with the EISCAT incoherent scatter radar have shown large rises in dayside, auroral plasma velocities (>2 km over a wide range of latitudes and lasting about an hour. These are larger than the neutral thermal speed, and allow, for the first time, observations of a no...
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.694.7745 http://www.eiscat.rl.ac.uk/Members/mike/publications/pdfs/1987/34_Winseretal_1987.pdf |
| Summary: | Abstract. Recent observations with the EISCAT incoherent scatter radar have shown large rises in dayside, auroral plasma velocities (>2 km over a wide range of latitudes and lasting about an hour. These are larger than the neutral thermal speed, and allow, for the first time, observations of a non-thermal plasma over a range of observing angles, revealing a clear angular dependence. The observed ion temperature anisotropy, deduced by assuming a Maxwellian line-of-sight ion velocity distribution, is at least 1.75, which exceeds the theoretical value for a bi-Maxwellian based on a realistic ion-neutral collision model. The aspect angle dependence of the signal spectra also indicates non-Maxwellian plasma. |
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