1996 Fiscal Year Final Research Report Summary
Caviton Induced Double Layr-Like Potential Structures in Plasmas
| Project/Area Number |
07680515
|
|---|
| 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 | Tokai University |
|---|
Principal Investigator |
TANIKAWA Takao Tokai University, Institute of Research and Development, Associate Professor, 開発技術研究所, 助教授 (70207174)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Yoshiharu The Institute of Space and Astronautical Science, Associate Professor, 宇宙科学研究所, 助教授 (20013708)
|
|---|
| Project Period (FY) |
1995 – 1996
|
| Keywords | Cavitons / Double Layrs / Langmuir Turbulence / Ion Holes / Resonance Absorption / Microwave-Plasma Interactions / Nonlinear Phenomena |
|---|
| Research Abstract |
A new mechanism for generating double layr-like potential structures at the location of a density cavity created by intense, localized electron plasma oscillation--caviton-- is experimentally investigated in a high-power microwave-plasma system.
1. Cavitons are localized electron plasma waves trapped inside density cavities which are generated by the ponderomotive forces associated with the localized waves themselves. It has been known that cavitons play an important role in plasmas which are in the state of strong Langmuir turbulence.
2. In this investigation, cavitons are created in an inhomogeneous plasma by utilizing the resonance absorption of a short microwave pulse (f=3GHz, peak power=60kW,pulse duration-1 mus). It has been found that a double layr-like potential structure can be generated associated with the formation of a caviton at the resonance layr (n-10^<11>cm^<-3>).
3. As the caviton is formed, a negative potential well appears at the location of the caviton. It has been found that this potential dip repels background electrons, causing the expansion of the low potential region to develop into a double layr-like potential structure.
4. The measurements of the ion distribution function suggest that an ion phase-space hole is generated during the above process. Data indicate that the ion phase-space hole is created near the location of the caviton and moves at approximately the ion acoustic speed. The role of this ion phase-space hole will be examined further in our future experiments.
5. The potential difference between the high and low potential regions of the caviton induced double layr-like potential structure saturates at-0.5 mus after the injection of the microwave beam, and it's value is proportional to the peak power of the incident microwave pulse.
6. The results of one-dimensional particle-in-cell computer simulations are consistent with our experimental results. Further simulation work is under way.
|
Research Products
(19 results)
