Study on the Production of Electron-Free Plasma and the Characteristics
| Project/Area Number |
03680019
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
プラズマ理工学
|
|---|
| Research Institution | THE INSTITUTE OF PHYSICAL AND CHEMICAL RESEARCH(RIKEN) |
|---|
Principal Investigator |
AMEMIYA.HIROSHI Plasma Physics Laboratory Senior Scientist, プラズマ物理研究室, 副主任研究員 (60087426)
|
|---|
| Project Period (FY) |
1991 – 1992
|
| Project Status |
Completed (Fiscal Year 1992)
|
| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1992: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1991: ¥1,100,000 (Direct Cost: ¥1,100,000)
|
|---|
| Keywords | Negative ion / Electron-free Plasma / Probe / Optogalvanics / Radio frequency discharge / Oxygen / D-layer / Sheath / 無電子 / 正負イオン / 磁気フィルタ / レ-ザ- |
|---|
| Research Abstract |
A negative ion plasma was generated by RF discharge between electrically floated parallel plates in a source section, which was surrounded by a multi-cusp magnetic field of grounded SmCo magnets.The RF power was transmitted through a bridge type matching circuit. Oxygen was flown between 1 and 60Pa. The second derivative of the probe current showed a peak of negative ions. The electron energy distribution was deficient in the lower energy range due to the attachment. The ratio alpha of the negative to positive ion density was alpha=0.3-0.5 depending on the pressure and the RF power. The plasma density could be above10^9cm^<-3>. The negative ion temperature was found to be 0.1-0.6eV. Then, an almost electron-free plasma was produced in the target section under optimum conditions. The saturation current ratio of the probe was as low as about 1.2. From the analysis, it follows that(1-alpha)<10^<-4>. The probe method was refined for the diagnostics of negative ion-plasmas. The sheath criterion necessary for the analysis was derived. A method for the case of very few residual electrons was given.
The laser optogalvanic (OG) technique was applied to detect nagative ions. Electrons photodetached from negative ions were measured in both cw and pulsed modes. A hollow cathode discharge was also used with the pressure of O_2 from 30 to 200Pa. Photodetached electrons acquired an energy of the same order as the electron temperature T_e. In the experiment with pulsed lasers, the waveform of the photedetached electrons showed a transient effect of the order of ion acoustic wave. Thus, the possibility of the optical control of negative ion-dominant plasmas was confirmed.
|
Report
(3 results)
Research Products
(18 results)
