2005 Fiscal Year Final Research Report Summary
Short Electromagnetic Wave Generation by Interaction between Short Pulse Laser and Mangetized Plasma
| Project/Area Number |
16340178
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Plasma science
|
|---|
| Research Institution | Utsunomiya University |
|---|
Principal Investigator |
YUGAMI Noboru Utsunomiya Univ., Engineering, Acc.Prof, 工学研究科, 助教授 (60220521)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
HIGASHIGUCHI Takeshi Miyazaki Univ, Engineering, Research Assistant, 工学部, 助手 (80336289)
|
|---|
| Project Period (FY) |
2004 – 2005
|
| Keywords | Teraherts / Electromagnetic Wave / Laser / Plasma / プラズマ |
|---|
| Research Abstract |
We conducted the short electromagnetic wave generation experiments by use of ultra-high power, short pulse laser system, whose maximum power is 1TW with pulse duration of 100 fs at the wavelength of 800 nm. The laser focused in the N2 gas with the pressure of 80 Pa. The laser can created plasma immediately and the strong radiation is observed from this region. To detect the electromagnetic wave, we used several detector which has specific frequency. These detectors can response the range from 30 to 300 GHz with the time resolution less than 100 ps. The frequency was determined by the Time of Flight technique which uses the frequency dispersion in the waveguide. The detected radiation pulse has the time duration of 200 ps for all of the range of the frequecies. The radiation emitted the conical direction with 30 degree from the laser created plasma with the radial polarization which can be measured by the rotating the waveguide and horn antenna. The cone angle decreases as the radiation frequency increases.
To explain these experimental data, we created the plasma model : The plasma column created by the intense laser pulse with the diameter of the focal size and the length of the Rayleigh length. The electrons expel by the ponderomotive force of the laser pulse. On the other hand, the ions remain the original position in the time scale which we are interested. Thus the electrons radially are oscillated by the electric force which created by the ion electric field. The radiation has TM01 mode in the waveguide and is emitted into free space. The calculation indicates the direction of the radiation with the angle of 30 degree and the radial polarization, which is good agreements with the experiments. Furthermore, it indicates the direction angle is the function of the radiation frequency.
These experimental data suggest the plasma parameters for generation of higher radiation frequency, ie, the terahertz radiation.
|
