2005 Fiscal Year Final Research Report Summary
Development of 2 color short-wavelength FIR laser interferometer and its application to the Large Helical Device
| Project/Area Number |
15360494
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Nuclear fusion studies
|
|---|
| Research Institution | National Institute for Fusion Science |
|---|
Principal Investigator |
MORISHITA Kazuo (川端 一男) National Institute for Fusion Science, Large Helical Device Project, Professor, 大型ヘリカル研究部, 教授 (60109353)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOKUZAWA Tokihiko National Institute for Fusion Science, Large Helical Device Project, Research Associate, 大型ヘリカル研究部, 助手 (90311208)
TANAKA Kenji National Institute for Fusion Science, Large Helical Device Project, Associate Professor, 大型ヘリカル研究部, 助教授 (50260047)
OKAJIMA Shigeki Chubu University, School of Engineering, Professor, 工学部, 教授 (90113084)
|
|---|
| Project Period (FY) |
2003 – 2005
|
| Keywords | Plasma Diagnostics / Interferometer / Laser / Two Color / Far-infrared / ヘリカルプラズマ |
|---|
| Research Abstract |
We have been developing a new two color far-infrared laser interferometer for the density measurement on the LHD and for the future large fusion devices. In the LHD, a 13ch FIR laser interferometer has been constructed and routinely operated for the precise measurements of the electron density profile almost every shot except in the case of a high-density plasma produced by an ice pellet injection. When a large sized pellet is injected into the plasma steep density gradient is formed, which sometimes causes the fringe jumps on the density traces measured by fringe counters. In order to overcome this difficulty we have been developing new laser sources in the wave length region of 40 to 70 μm, and achieved high power laser lines oscillating simultaneously at 57.2 and 47.6 μm. These two color laser lines enable us to construct a new two color laser interferometer.
In order to construct a short wavelength laser interferometer, the choice of optical materials for a vacuum window and a beam
… More
splitter is important. A crystal quartz etalon, which is often used in a FIR region, has a large absorption around 50 μm. We have confirmed that a CVD-Diamond is an excellent material for the short wavelength region. The absorption coefficient and the refractive index at 57.2 μm are 0.19±0.05 cm^<-1> and 2.383±0.002, respectively. The application of the CVD-Diamond is, however, limited to apply to the special components, since the large sized beam-splitters/combiners are too expensive. So, we have investigated the optical constants of Silicon at 57.2 and 47.6 μm, and found that Silicon can be used as optical components for laser diagnostics around 50 μm. By introducing Ge : Ga photoconductive detectors operating at liq. He temperature, we have successfully detected two color beat signals (0.5 MHz and 1.2 MHz) with excellent signal to noise ratio (〜40 dB). These beat signals were fed into phase comparators for phase measurement after passing through band-pass filters. And we found that two color FIR laser work was successful in demonstration of mechanical vibration compensation Less
|
Research Products
(24 results)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
[Book] プラズマ診断の基礎と応用2005
Author(s)
間瀬淳, 雨宮宏, 菅井秀郎, 東井和夫, 川端一男他
Total Pages
377
Publisher
コロナ社
Description
「研究成果報告書概要(和文)」より
