2005 Fiscal Year Final Research Report Summary
Formation of Viscous Vortex and Anomalous Viscosity in a Plasma
| Project/Area Number |
15340202
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Plasma science
|
|---|
| Research Institution | KYUSHU UNIVERSITY (2005)
National Institute for Fusion Science (2003-2004) |
|---|
Principal Investigator |
TANAKA Masayoshi Kyushu University, High Energy Eng.Sci, Professor, 大学院総合理工学研究院, 教授 (90163576)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YOSHIMURA S. National Institute for Fusion Sci, Research Assistant, 大型ヘリカル研究部, 助手 (50311204)
KONO M. Chuo University, Policy Studies, Professor, 総合政策学部, 教授 (00038564)
|
|---|
| Project Period (FY) |
2003 – 2005
|
| Keywords | vortex / anomalous viscosity / LIF Doppler spectroscopy / plasma hole / viscous vortex / 粘性渦 |
|---|
| Research Abstract |
We have observed a vortex with a density cavity in its core, in a magnetized cylindrical plasma. The density of the hole region is one tenth of that in the peripheral plasma. The space potential has a strong peak in the core, and the resulting radial electric field becomes as high as 40 V/cm, which drives an azimuthal rotation at a supersonic velocity. It is also found that in the core region, centrifugal force dominates the electric force to be balanced with the Lorenz force, leading to a rigid rotation of the core. The flow velocity field has benn measured with a directional Langmuir probe, and it revealed that the plasma hole has a sink flow to the core on a plane perpendicular to the magnetic field and also an axial flow. The vorticity distribution determined by the flow velocity field shows localization near the center axis, which means that the viscosity of the plasma is finite and causes radial transport of vorticity. According to the flow velocity field and the vorticity distribution, the plasma hole is identified as a Burgers vortex, which is intrinsic in viscous fluids and is observed in a plasma for the first time. The effective viscosity estimated from the characteristic scale length of vorticity localization exhibits an anomaly, which is three orders of magnitude higher than the classical value.
|
