1998 Fiscal Year Final Research Report Summary
Reversed Magnetic Shear Formation by RF
| Project/Area Number |
09680470
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
プラズマ理工学
|
|---|
| Research Institution | Osaka Institute of Technology |
|---|
Principal Investigator |
NAKAMURA Masahiko Faculty of Eng.Osaka Institute of Technology, Associate Professor, 工学部, 助教授 (50172440)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
MAEKAWA Takashi Graduate School of Energy Science, Kyoto University, Professor, 大学院・エネルギー科学研究科, 教授 (20127137)
|
|---|
| Project Period (FY) |
1997 – 1998
|
| Keywords | tokamak plasma / RF current drive / current profile / MHD instability |
|---|
| Research Abstract |
The purpose of this investigation is to control the plasma transport and MHD activity by local RF current drive, In this investigation, RF power is applied by the injection of microwave in the frequency range of electron cyclotron wave. In order to get local RF-driven current, it is necessary to focus the microwave beam into narrow region. Microwave power transmission system was developed and we obtained quite narrow beam spot ( 1.5cm * 2.2cm), which is sufficiently narrow compared with plasma cross section.
When microwave is injected into plasma, RF-driven current was generated. The amount of this current IRF was monitored by the change in the loop voltage. IRF IRF was dependent on the direction of incident microwave, Further, the direction of IRF was opposite when the injection angle of microwave was reversed. Maximum value of IRF was about lOkA, which was less than 10% of total plasma current across the whole plasma cross section. However, IRF was drive in so narrow region that it changed the local magnetic configuration efficiently. The result was confirmed by the following facts. When was dirven on the magnetic axis region in the inverse direction of Ohmic current, sawthooth instability was suppressed. The result showed that inverse RF current drive reduced the current density of the central region, resulting in the increase of the central safety factor.
|
