2006 Fiscal Year Final Research Report Summary
Formation of Burgers Vortex and its Dynamics in Magnetized Plasmas
| Project/Area Number |
16540453
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Plasma science
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| Research Institution | Chuo University |
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Principal Investigator |
KONO Mitsuo Chuo University, Faculty of Policy Studies, Professor, 総合政策学部, 教授 (00038564)
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| Project Period (FY) |
2004 – 2006
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| Keywords | anomalous E x B drift / density hole / anomalous viscosity / weakly ionized plasma |
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| Research Abstract |
1. A stationary solution has been obtained which shows a good agreement with the observed typhoon-like vortex in axi-symmetric system and physics behind the typhoon-like vortex has been given.
2. There are two branches for the E x B drift if a centrifugal force is included. One is well known ordinary E x B drift which is determined by a balance of the Lorenz force and the potential force. Newly recognized one is an anomalous E x B drift which is realized by the Lorenz force and the centrifugal force. Since the anomalous E x B force is proportional to radial coordinate and diverges at infinity, usually this branch can be ignored. However in a typhoon like vortex, the core part of the vortex is explained by the anomalous E x B drift. Outer part of the vortex is described by an ordinary E x B drift. Thus an anomalous E x B drift is first to be identified as a physical process.
3. From the force balance, the density structure is determined by the centrifugal force. The density is low at the center and increases toward the edge of the vortex. Thus the plasma has a hole at the center.
4. Corresponding to the density structure the radial flow converges towards the center which is converted into an axial flow.
5. The axial flow in the core part of the vortex is directed toward up-stream while the axial flow outside the vortex is directed to down-stream, which suggests the axial flow is characterized by a multiple cell structure. However this has not been fully understood.
6. The potential is maximum at the center and decreases towards the edge of the vortex. The maximum of the azimuthal velocity is 1.5 times the ion sound velocity and the radial velocity is 0.5 times the ion sound velocity. Therefore the inward ion velocity is super-sonic and satisfies the Bohm condition to create a mid-air sheath. This is left unsolved.
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