22P019-O
Characteristics of Vacuum Ultraviolet Emissionin Coaxial Type Low-pressure Micro Plasma
同軸型低気圧マイクロプラズマの真空紫外放射特性
Shunsuke Tajiri and Hiroshi Fujiyama
田尻俊介，藤山 寛
Graduate School of Engineering, Nagasaki University.
1-14 Bunkyo, Nagasaki 852-8521, Japan
長崎大学 工学研究科 〒852-8521

長崎市文教町1-14

In the coaxial type low pressure micro plasma, the radiated ultraviolet (UV) rays were measured
by vacuum ultraviolet (VUV) spectroscopy measurement. Here, the VUV emission
characteristics in the low-pressure micro plasma will be reported.

1. IntroductionIn the recent days, the plasma display panel(PDP) uses Ne-Xe mixture gas and generates themicro plasma for high-pressure condition. However,self absorption of 147nm VUV emission by Xe
atom happens in the high-pressure gas, andluminance efficiency is drastically decreased.
Fujiyama et al. has succeeded in generating thehigh ionizing level micro plasma for the electronic
density exceed 1011cm-3 in the low-pressure andshort gap length area by using resonantly
confinement effect of electron at 2nd harmonic ECR
condition and mirror magnetic field confinement
effect [1]. Therefore, it is thought that thehigh-efficiency VUV rays source is obtained bygenerating the micro plasma in the low-pressureand short gap length area, and by decreasing
self-absorption.
In the present study, the VUV rays emitted fromthe low-pressure micro plasma source were
examinedbyusing
VUV
spectroscopy
measurement.
2. Experimental
Figure 1 shows the experimental setup. The
chamber has been exhausted to the vicinity of

10-6Torr with the turbo-molecular pump and therotary-pump. Pure Xe gas was injected, and the lowpower microwave of 2.45GHz was applied by acoaxial cable in the TEM mode. Micro plasma wasgenerated between the coaxial electrodes in themirror-type magnetic field. VUV spectroscope wasused for the spectral instrument. And the disperse
wave length of the VUV spectroscope can change
arbitrarily by using scan controller. Photo-multiplier
was used for photo detection. The output signal
amplified by the photo-multiplier was measured
with the oscilloscope. Moreover, VUV spectroscope
has been exhausted to the vicinity of 1×10-3Torr
with the turbo-molecular pump and therotary-pump.
3. Results and Discussions
The emission spectrum distri bution wasobserved by using scan controller. In the result, theemission peak of Xe could be confirmed at thewavelength of about 147 nm. In the present
experiment, it was investigated on the magnetic
field dependence of the Xe peak at wavelength
147nm. Figures 2 and 3 show the magnetic fielddependence for the gap length of 1mm and 3mm,respectively. It is noted that the emission peakEmission Intensity [a.u.]=147nm

strength had the maximum value at ωc/ω=0.5 asshown in Fig.2 and the emission peak strength had
the maximum value at ωc/ω=1.0 as shown in Fig.3.
Therefore, in the shorter gap length, the maximum
VUV peak intensity is obtained at the 2nd harmoniccondition, ωc/ω=0.5. It means that the 2nd harmonic
ECR plasma can emit VUV effectively in micro
plasma with narrow gap length. It can be explainedby the experimental result so that the electron
density had the maximum value at ωc/ω=0.5. On theother hand, for the wide gap length, the electron
temperature had the maximum value at ECR
condition, ωc/ω=1.
Gas : Xe
Gap Length : 1mm
Microwave Power : 10W
40mTorr
30mTorr
20mTorr
10mTorr

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Magnetic Field ω c/ω
Fig.2. Magnetic Field Dependency of Emission
Peak Intensity (Gap Length=1mm)

1Emission Intensity [a.u.]=147nm

Fig.1. Experimental Setup
40mTorr
30mTorr
20mTorr
10mTorr

Gas : Xe
Gap Length : 3mm
Microwave Power : 10W

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Magnetic Field ω c/ω

Fig.3. Magnetic Field Dependency of Emission
Peak Intensity (Gap Length=3mm)

4. Conclusion
In this study, the VUV rays emitted from thelow-pressure micro plasma source were examinedby using VUV spectroscopy measurement. And, it
was investigated on the magnetic field dependenceof the Xe peak at wavelength 147nm. In the result,it was noted that the 2nd harmonic ECR plasma canemit VUV effectively in micro plasma with narrow
gap length because the electron density had themaximum value at ωc/ω=0.5.
Reference[1] H. Fujiyama et al: Proc. of the 17th International
SymposiumonToronto (2005).

PlasmaChemistry(ISPC-17),