23P061-P
Measurement and Control of Plasma Turbulence in PANTAPANTAにおけるプラズマ乱流計測及び動的制御実験の現状	 
Shigeru Inagaki1, 2, Yoshihiko Nagashima1,2, Stella Oldenbürger3, Tatsuya Kobayashi1,
Katsuyuki Kawashima1, Noriko Ohyama1, Yuuki Tobimatsu1, Hiroyuki Arakawa4,Takuma Yamada3,5, Masatoshi Yagi2,3,4, Naohiro Kasuya3,6, Makoto Sasaki2,3, Akihide Fujisawa2,3,
Sanae-I. Itoh2,3, Kimitaka Itoh3,6
稲垣滋1,2,	 永島芳彦1,2,	 Stella	 Oldenbürger2,	 小林達哉3,	 川島勝之3,大山乃里子3,	 	 
飛松祐紀3,	 荒川弘之4,	 山田琢磨2,5,	 矢木雅敏1,2,6,	 糟谷直宏2,7,	 佐々木真1,2,	 藤澤彰英1,2,	 伊藤早苗1,2,	 伊藤公孝2,7	 
1Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan1
九州大学応用力学研究所 〒816-8580 福岡県春日市春日公園6-1
2
Itoh Research Center for Plasma Turbulence, Kyushu University,
6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan2
九州大学伊藤極限プラズマ研究連携センター 〒816-8580 福岡県春日市春日公園6-1
3Interdisciplinary Graduate School of Engineering Sciences, Kyushu University,
6-1 Kasuga-koen, Kasuga, Fukuoka 816-8580, Japan3
九州大学総合理工学府 〒816-8580 福岡県春日市春日公園6-1
4Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193, Japan4
日本原子力研究開発機構 〒311-0193 茨城県那珂市向山801-1
5Graduate School of Frontier Sciences, The University of Tokyo,
5-1-5 Kashiwanoha, Kashiwa, Tokyo 277-8561, Japan5
東京大学新領域創成科学研究科 〒277- 8561 千葉県柏市柏の葉5-1-5
6Japan Atomic Energy Agency, 2-166, Omotedate, Obuchi, Rokkasho-mura, Aomori, 039-3212 Japan6日本原子力研究開発機構 〒039-3212	  青森県六ヶ所村尾駮表舘2番166
7
National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292, Japan7
核融合科学研究所 〒509-5292 岐阜県土岐市下石町322-6
To understand fluctuation dynamics in magnetized plasma, a linear magnetic confinement device wasintroduced. In this device, precise spatiotemporal structure measurements of turbulence were developedand established. A turbulence control experiment by an endplate biasing was performed.

1. Introduction
The changes in turbulent structure andtransport occur in much faster time scale than that
expected from diffusive processes. The dynamicchanges in transport are important issues forcontrol the burning plasma states, thus, theunderstanding of dynamic transport response
should be mandatory. According to the recent
achievement, the new concept is being
established that the meso-scale fluctuating
structure such as zonal flows and streamers
coexist with micro-scale fluctuations, so as toregulate the turbulent transport. It provides one
possible path to explain the problem of dynamictransport response. Understanding of dynamics ofturbulent structure formation is crucial. The
purposes of this study are i) to develop andadvance the physics of turbulent plasma and ii) tounderstand the fluctuation dynamics.
To achieve this project, a basic experimental

device has been introduced. The small device
provide an excellent environment to investigate
fundamental processes and non-linear dynamics
associated with turbulence phenomena, giving aphysical understanding of plasma turbulencecommon for high temperature plasmas. Here, wereport specifications of device and initial resultsof a fluctuation control experiment.
2. PANTAPANTA (Plasma Assembly for Nonlinear
Turbulence Analysis) is a linear magnetic plasma
confinement device. A schematic view of PANTA
is shown in Fig. 1. The cylindrical vacuum vessel
has a diameter of 0.457 m and a length of 4.05 m.
The device is built in a modular way and iscomposed of 11-modular sections. We canchange a module for another one so as to easieraccess to plasma and to adapt a special
experimental purpose. The axial magnetic field iscreated by 18 field coils. The coils can be moved
on rails and this allows us to change the magnetic
field configuration easier. The coils are usuallydistributed along the whole column with equal
separation and create a linear magnetic field
configuration. The maximum magnetic field is
0.15 T in the linear configuration. In addition,two independent coil power supplies can increase
freedom of the magnetic configuration flexibility.
The plasmas in PANTA are produced by helicon
wave and/or electron cyclotron wave. The heliconsource consists of a double-loop antenna wrappedaround a glass cylinder with a diameter of 10 cm.
It is powered with a 7MHz, < 10kW (typical3kW) radio frequency. The electron cyclotron
wave is excited by a 2.45GHz, 5kW magnetron.
Argon (or Helium) gas is constantly injectedclose to the source through a mass flow controller
and is pumped by two main turbo-molecular
pumps close to the endplate and two sub-pumps
in the middle of device. Two insulated baffle
plates with the inner diameter of 15 cm areinstalled close to the source and endplate forneutral gas control.

temperature fluctuation measurement by animproved triple probe method is established [2]. A
224-channel data acquisition system with external
clock (jitter < 10 ns) allows us simultaneous
multi-point
measurement
andhigher-ordercross-correlation analysis of fluctuations.
4. Dynamic Control of Fluctuation
To observe the dynamic behaviors offluctuations, the dynamic electrode biasing
experiments are planed. The insulated endplateallows us biasing it and the endplate biasing
experiments have been performed. The endplatebiasing successfully changed potential structure
as shown in Fig. 2. The impacts of the biasing on
the fluctuation structure will be discussed.

Fig. 2. Time evolution of floating potential at r = 4 cm.
An endplate is biased to 10 V during discharge. The
probe is separated 2 m from the endplate along magnetic
field line. The endplate is electrically floated before andafter biasing.
Fig.1. Schematic view of PANTA

3. Diagnostics
Langmuir probe is most suitable to measurefluctuations and equilibrium radial profiles ofplasma parameters, such as electron density,
electron temperature and plasma potential.
Equilibrium profiles are measured with radial
movable probes (with and without rf-compensation)
by applying the single-, double- triple-probe
methods. A 4-tips Mach probe is also used tomeasure equilibrium profiles of parallel- andperpendicular ion flow velocities. Spatiotemporal
structure of fluctuation is measured withmulti-channel probe arrays. A 64-channel azimuthalprobe array and 5-channel (3-channel) radial probearrays can measure three-dimensional structure ofion saturation current and floating potential
fluctuations [1]. The fluctuation-driven radial
particle flux can be also estimated fromsimultaneous measurement of density and poloidal
electric field fluctuations with the movable3-channel azimuthal probe array. In addition,

5. Summary
Plasma turbulence experiments have been
conducted in PANTA. Fluctuation measurementwith usual probes and advanced diagnostics such asion flow measurement and temperature fluctuation
measurements are developed and established.
Turbulence control experiments by the endplatebiasing have been started. Dynamic control ofplasma turbulence and precise spatiotemporal
structure measurement of turbulence are the mostimportant issues in this project.
Acknowledgments
This work is partly supported by a grant-in-aid
for scientific research from JSPS (21224014,23360414) and by the collaboration programs ofNIFS (NIFS10KOAP023) and of the RIAM ofKyushu University.
References[1] This conference: 23P062-p, 23P063-p, 23P064-p[2] K. Kawashima et al.: Plasma Fusion Res. 6 (2011)2406118