22P101-P
Radiation spectra measurements by using the multi-channel spectroscopic
measurement system in the central cell of GAMMA10
多波長同時計測分光器を用いたGAMMA10セントラル部の放射スペクトル測定
Kitade Shuji, Masayuki Yosikawa, Yosuke Nakashima, Tohru Mizuuchi, Shinji Kobayashi,
Katsuhiro Hosoi and Tsuyoshi Imai
北出崇二1), 吉川正志1), 中嶋洋輔1), 水内亨2), 小林進二2), 細井克洋1), 今井剛1)
Plasma Research center,University of Tsukuba
1-1-1-1F, Tennoudai, Tsukuba, Ibaraki 305-8577, Japan筑波大学プラズマ研究センター 〒305-8577 茨城県つくば市天王台1-1-11)
Plasma Research Center, University of Tsukuba2)
Institute of Advanced Energy, Kyoto University

Experiments of molecular gas fueling with Supersonic Molecular Beam Injection (SMBI) device werecarried out under the collaboration with Kyoto University. Radiation spectra from a plasma with SMBI
were measured by using the multi-channel spectroscopic measurement system in the central cell ofGAMMA10. In order to investigate the effects on plasma by SMBI, the density ratio between hydrogenmolecular and atoms (n H2/nH) is calculated with Collision-Radiation model (CR-model). The density ratio
between hydrogen molecular and atoms during SMBI were estimated amount about 600 times larger thanthat without SMBI.

1. Introduction
Experiments of Supersonic Molecular Beam
Injection (SMBI) device were carried out under thecollaboration with Kyoto University. SMBI device
is set for injection hydrogen gas fueling in thecentral cell of GAMMA10.
We study the effects on spectra during SMBI byusing the multi-channel spectroscopic measurement
system. Moreover, the density ratio betweenhydrogen molecular and atoms during SMBI wascalculatedwith
Collision-Radiation
model(CR-model).
2. Experiment Apparatus
GAMMA 10 is a 27m long tandem mirror
plasma confinement device with a thermal barrier. It
consists of a 5.6m long axisymmetric central cell,
twoanchorcells
forsuppressing
magnetohydrodynamics (MHD) instabilities thatare located in both ends of the central cell. Twoplug/barrier cells are connected to the anchor cells
for forming the plug and thermal barrier potentials.
In plasmas produced in the core region of thecentral cell, typical electron density, electron
temperature and ion temperature are about 2×1012

cm-3, 100 eV and 5 keV, respectively.
SMBI device is set for fueling hydrogen gas
into the plasma in the central cell. SMBI device caninject supersonic hydrogen gas squeezing highpressure with pulse-valve. SMBI device canconfigure the plenum gas pressure with regulator,
and regulate pulse width and the injecting timingwith pulse control power. The maximum plenum
gas pressure of SMBI is 2.5MPa.
The multi-channel spectroscopic measurement
system is set to measure 200-700nm spectra withkeeping enough wavelength resolution in thecentral cell. Figure 1 shows schematic of themulti-channel spectroscopic measurement system.
The lights collected by the lens lead to the twospectrometers (USB2000, Ocean Optics Inc.)
through the optical fiber. One spectrometermeasures 200-400nm spectra, and another one
measures 400-700nm spectra. The spectrometer hasa CCD as a detector and is controlled byWindowsPC through the USB cable. The exposure
time of it is typically 50ms.

Collective Lens

18cm

PlasmaHα and Hβ is shown in eq.(2),Spectrometer

Optical FiberΦ =50mm
f=200mmwavelength
1:200-500nm
2:400-700nm
Slit:5μ m
Grating:1200 Lines/mm

L=5m

Line of sight

1to PC65cm

2to PC

Fig. 1. The multi-channel spectroscopic measurement system.

3. Experimental Results
Figure 2 shows diamagnetism and electron line
density (a) and the radiation spectrum during SMBI(b) measured by using multi-channel spectroscopic
measurement system. The plasma is the hot ion mode
plasma. The Gas-puffing#7 injects the hydrogen gas(250 Torr) at 120-127 ms. SMBI injects the hydrogengas (1.5 MPa) at 170-171 ms. At 170-175 ms (duringSMBI period), the diamagnetism decreases much,and the electron line density adversely increases
much.
1Diamgnetism[10 -4 Wb]

8DM0.66NL0.4

40.2

02GP#750100SMBI150200250.
Here, I, A,and R are radiation intensity, the radiativetransition probability, and the population coefficient,respectively. The population coefficient depends onboth ne and Te.
Hβ/Hα02827150100

Electron Temperature[eV]

H α (656.2nm)

200

23.6±3Figure 3 shows the calculated result ofCR-model. This figure plots nH 2 / nH (the densityCR-modeln e =2.28×10 12(b)250

Te [eV]The evaluation of nH 2 / nH  1/10 in ordinary plasma.
The density ratio increase about 600 times as large asthat of ordinary plasma.

300

H β (486.1nm)

Intensity[μ W/sr cm 2 nm]

Hα [a.u.]

51.7

350

500Ne
[1012cm-3]
331.4
0.16
2.3
Table 1 Itensity and ParametersHβ [a.u.]Time[ms]
Spectra During SMBI

(2)

ratio between hydrogen molecular and atoms) as afunction of Te. We apply Te (Te=23.6±3eV) to thefunction in this figure, and get nH 2 / nH  60～75 .

Electro Line Density[10 13 cm -3 ]0.8

10#218420(a)R2 (4) nH 2)()
I H  H AH  R1 (4)R1 (4) nHI H H  AH R1 (3)R (3) nH
1  ( 2 )( 2 )R1 (3) nH
1 (262524232221300

350

400

450500

Wavelength[nm]550600650

7002040Fig. 2. Diamagnetism, Electron line density, radiation spectra
during SMBI

80100120140n H2 /n HFig. 3. The result of CR-model

H α (656.2nm) and H β (486.1nm) spectra
increase by SMBI. Table 1 shows the radiation
intensities and plasma parameters during SMBI.
The density ratio between hydrogen molecular andatoms were calculated with CR-model. CR-model
uses the radiation intensity, ne (from the microwaveinterferometer) and T e (from the Thomson
scattering measurement). The expression of theradiation intensity ratio is shown in eq.(1),{R1 (i)ne n(1)  R2 (i)ne ni }A(i, k )I (i, k )
I ( j, k ) {R1 ( j )ne n(1)  R2 ( j )ne ni }A( j, k )

60

(1)

.
Then, the expression of the intensity ratio between

4. Summary
We measured the changes of the radiation
spectra during SMBI by using the spectroscopic
measurement system. Hα and Hβ spectra increasemuch by SMBI.
The density ratio of atomic and molecularhydrogen was calculated with CR-model.
5. Reference[1] K. Matama : Plasma Conference (2006) 01aC04P.
[2] T. Mizuuti : Contrib. Plasma Phys. 50, No.6-7,639-645 (2010).
[3] R. Yonenaga : Plasm Fusion Res, 5 S2045 (2010).