23P036-P
Study of filament features of edge plasma fluctuations using fast video cameras
with a combination of Langmuir probe measurements in Heliotron J (II)N. Nishino1, L.Zang2, M. Takeuchi3, T. Mizuuchi4, S. Ohshima5, K. Kasajima6, M.Sha2, K. Mukai2,
H.Y. Lee2, K. Nagasaki4, H. Okada4, T. Minami4, S. Kobayashi4, S. Yamamoto4, S. Konoshima4,
K. Hanatani4, Y. Nakamura2, and F.Sano4

西野信博1，臧 臨閣2，竹内正樹3，水内亨4，大島慎介5，笠嶋慶純6，沙 夢雨2，
向井清史2，李炫庸2，長崎百伸4，岡田浩之4，南貴司4，小林進二4，山本聡4，木島滋4，花谷清4，中村祐司2，佐野史道4
1

Graduate School of Engineering, Hiroshima University, Higashi-hiroshima, Japan
2
Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Japan
3
Naka Fusion Institute, Japanese Atomic Energy Agency, Naka, Japan
4
Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Japan
5
Pioneering Research Unit for Next Generation, Gokasho, Uji, Japan
6
Department of Engineering, Kyoto University, Kyoto, Japan京都大学エネルギー理工学研究所〒611-0011 宇治市五ヶ庄

In Heliotron J a combination system of a fast camera, a gas puff and a hybrid probe is installed first timefor the edge plasma turbulence study. This complex system enables us to get good information on plasma
turbulence and its behavior, especially the dynamics of the filament structure, in the edge region. Up tonow we have testified the gas puff system for GPI, in particular the quantity of gas puff is very sensitive forHeliotron J plasma. In this meeting we will report mainly the first observation of filament images with GPIand SMBI (another port) in NBI plasma.

1. Introduction
Applying a supersonic molecular beaminjection (SMBI) [1] to Heliotron J plasma theplasma stored energy increased beyond thesaturation level in the conventional gas puff
condition [2]. The previous experiments suggestthat some change in the edge plasma turbulence(ex. dynamics of a filament structure in theturbulence) might be related to the observed
difference in the plasma performance between theSMBI and the conventional gas puff cases.

ECH

Fig.1 Top view of Heliotron J. The locations offast cameras, the gas puff for GPI and thehybrid probe are illustrated.

Therefore, the effect of SMBI on the behavior offilament structure in the edge plasma turbulenceis very interesting from the viewpoint of fuelingand plasma turbulence itself. Fast cameras or
combination probes of Langmuir/magnetic probes
have been used to study the behavior of edge
plasma in many devices [3–7], where in particularsimultaneous measurement with a fast camera andprobes is very powerful.
In this paper, the behavior of edge plasma
turbulence during SMBI was studied using a
combination of the fast camera with GPI,
Langmuir probes and a set of magnetic probes in
Heliotron J.
2. Experimental Setup
Heliotron J is a medium sized helical-axis
heliotron device with an L = 1/M = 4 helical coil [8,9]. Figure 1 shows a top view of Heliotron J and thelocations of fast cameras and the other equipment
referred to this study. Also, the vacuum flux
surfaces of the standard field configuration ofHeliotron J [11] at the fast camera measurement
port section, #14.5, are shown in Fig. 2. Due to thelimitation of the port space a fast camera is installedat the lower port and a gas puff for GPI (gas puffimaging) and a hybrid probe system are installed at
the upper port, respectively. In this experiment

FASTCAM SA5 (Photron) and FX K-5 (NACimage technology) are used to take high-speed
movies of Heliotron J plasma.

This frequency range is out of the detectablefrequency range of the magnetic probes. This low
frequency instability is believed to be an MHD
activity probably caused by too much amount ofgas injection in this particular case. Therefore, The
adjustment of gas quantity would help us to getbetter results.
In this meeting we will report the precise resultsof this complex measurement included in the fastcamera of NBI experiment and if in time, we will
also present those results of ECH and/or ICRF
experiment.
Gas puff port

Probe head
Faraday shield of
ICRF antenna

Fig. 2 Crosssection of #14.5 port section where ICRF
antenna is installed. The fast camera is set at thebottom port and the gas-puff and the hybrid probe areinstalled at the top port. The vacuum flux surfaces ofthe standard field configuration are also illustrated.

3. SMBI with GPIIn this experiment the gas puff at #14.5 is used
for GPI to enhance the brightness from the probeside of the edge plasma, and the filament images inthis side are observed by the fast camera. The
hybrid probe system provides data of ion saturation
current Is, floating potential Vf, and three directional
magnetic fluctuation simultaneously. Therefore, wecan measure many of key local parameters
associated with the filament behavior.
Up to now a lot of amount of injection gas for
GPI is required to observe the filament structure by
the fast camera and the increase of electron density
is not so small. We have to adjust the gas puff
quantity in near future. A typical fast camera image
with GPI at #14.5 is shown in Fig.3. This figure
shows the positions of the upper ICRF antenna in
the right side, the hybrid probe system in the centerand the gas puff exit in the left side, respectively.
Due to GPI it is thought that the fast camera image
mainly comes from the upper side of the peripheral
plasma.
During SMBI at #11.5, the suppression of themagnetic fluctuation is observed from power
spectra of the magnetic probe signal from thehybrid probe system at #14.5. On the other hand,the fluctuation of Is was not suppressed perhaps due
to excitation of a very low frequency instability.

RFig.3 Snapshot image of an NBI plasma with SMBI(#11.5) and GPI (#14.5) at #14.5
The stripe in the right side is Faraday shield of ICRF
antenna. Major radius direction is right.

Acknowledgments
The authors are grateful to the Heliotron
supporting group for their excellent arrangement ofthe experiments. This work is performed with thesupport and under the auspices of the Bi-directionalcollaboration research program (NIFS04KUHL006)
between Hiroshima University and IAE Kyoto
University. One of the authors (N.N) acknowledges
S. Nishino for continued encouragement.
References[1] L. Yao, in: New Developments in Nuclear Fusion
Research, Nova Sci. Pub, 2006, 61–87.
[2] T. Mizuuchi, et al., to be published in J.Nucl.Mater.
[3] R. Maqueda et al.. Rev. Sci. Instrum., 72 (2001),
931.
[4] S.J. Zweben et al.. Phys. Plasmas, 9 (2002), 1981.
[5] T. Mizuuchi et al.. J. Nucl. Mater., 337–339 (2005),
332.
[6] N. Nishino et al.. J. Nucl. Mater., 363–365 (2007),628.
[7] F. Sano et al.. J. Plasma Fusion Res. Ser., 3 (2000),26.
[8] T. Obiki et al.. Nucl. Fusion, 41 (2001), 833.