scholarly journals Kinetic Theory of Ion Acoustic Waves Observed at Comet 67P/Churyumov–Gerasimenko

2019 ◽  
Vol 880 (1) ◽  
pp. L13 ◽  
Author(s):  
Saeed ur Rehman ◽  
Asif Shah ◽  
Qamar ul Haque
Keyword(s):  
Kinetic Theory ◽  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Ion Acoustic ◽  
Comet 67P

scholarly journals Ion acoustic waves at comet 67P/Churyumov-Gerasimenko

2017 ◽  
Vol 600 ◽  
pp. A3 ◽  
Author(s):  
H. Gunell ◽  
H. Nilsson ◽  
M. Hamrin ◽  
A. Eriksson ◽  
E. Odelstad ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Ion Acoustic ◽  
Comet 67P

Kinetic theory of ion acoustic waves in a plasma with collisional electrons

1995 ◽  
Vol 52 (6) ◽  
pp. 6759-6776 ◽  
Author(s):  
V. Yu. Bychenkov ◽  
J. Myatt ◽  
W. Rozmus ◽  
V. T. Tikhonchuk
Keyword(s):  
Kinetic Theory ◽  
Acoustic Waves ◽  
Ion Acoustic Waves ◽  
Ion Acoustic

Kinetic Theory of Electron-Plasma and Ion-Acoustic Waves in Nonuniformly Heated Laser Plasmas

1998 ◽  
Vol 80 (11) ◽  
pp. 2322-2325 ◽  
Author(s):  
Bedros B. Afeyan ◽  
Albert E. Chou ◽  
J. P. Matte ◽  
R. P. J. Town ◽  
William J. Kruer
Keyword(s):  
Kinetic Theory ◽  
Acoustic Waves ◽  
Electron Plasma ◽  
Ion Acoustic Waves ◽  
Laser Plasmas ◽  
Ion Acoustic

scholarly journals Ion acoustic waves near a comet nucleus: Rosetta observations at comet 67P/Churyumov–Gerasimenko

2021 ◽  
Vol 39 (1) ◽  
pp. 53-68
Author(s):  
Herbert Gunell ◽  
Charlotte Goetz ◽  
Elias Odelstad ◽  
Arnaud Beth ◽  
Maria Hamrin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Acoustic Waves ◽  
Magnetic Field Gradient ◽  
Ion Acoustic Waves ◽  
Ion Distributions ◽  
Ion Acoustic ◽  
Low Energies ◽  
The Waves ◽  
Comet 67P ◽  
The Magnetic Field

Abstract. Ion acoustic waves were observed between 15 and 30 km from the centre of comet 67P/Churyumov–Gerasimenko by the Rosetta spacecraft during its close flyby on 28 March 2015. There are two electron populations: one cold at kBTe≈0.2 eV and one warm at kBTe≈2 eV. The ions are dominated by a cold (a few hundredths of electronvolt) distribution of water group ions with a bulk speed of (3–3.7) km s−1. A warm kBTe≈6 eV ion population, which also is present, has no influence on the ion acoustic waves due to its low density of only 0.25 % of the plasma density. Near closest approach the propagation direction was within 50∘ from the direction of the bulk velocity. The waves, which in the plasma frame appear below the ion plasma frequency fpi≈2 kHz, are Doppler-shifted to the spacecraft frame where they cover a frequency range up to approximately 4 kHz. The waves are detected in a region of space where the magnetic field is piled up and draped around the inner part of the ionised coma. Estimates of the current associated with the magnetic field gradient as observed by Rosetta are used as input to calculations of dispersion relations for current-driven ion acoustic waves, using kinetic theory. Agreement between theory and observations is obtained for electron and ion distributions with the properties described above. The wave power decreases over cometocentric distances from 24 to 30 km. The main difference between the plasma at closest approach and in the region where the waves are decaying is the absence of a significant current in the latter. Wave observations and theory combined supplement the particle measurements that are difficult at low energies and complicated by spacecraft charging.

scholarly journals Ion acoustic waves near a comet nucleus: Rosetta observations at comet 67P/Churyumov-Gerasimenko

2020 ◽  
Author(s):  
Herbert Gunell ◽  
Charlotte Götz ◽  
Elias Odelstad ◽  
Arnaud Beth ◽  
Maria Hamrin ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Propagation Direction ◽  
Wave Power ◽  
Comet Nucleus ◽  
Frequency Range ◽  
Ion Acoustic Waves ◽  
Ion Acoustic ◽  
The Waves ◽  
Comet 67P ◽  
Bulk Speed

Abstract. Ion acoustic waves were observed between 15 and 30 km from the centre of comet 67P/Churyumov-Gerasimenko by the Rosetta spacecraft during its close flyby on 28 March 2015. There are two electron populations: one cold at approximately 0.2 eV and one warm at approximately 4 eV. The ions are dominated by a cold (a few hundredths of eV) distribution with a bulk speed of (3–3.7) km/s. Near closest approach the propagation direction was within 50 degrees from the direction of the bulk velocity, leading to a Doppler shift of the waves that in the spacecraft frame cover a frequency range up to approximately 4 kHz. The wave power decreased over cometocentric distances from 24 to 30 km. The main difference between the plasma at closest approach and in the region where the waves are decaying is the absence of a significant current in the latter.

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