05aB01
トレーサー内蔵ペレットを用いたプラズマ計測
Plasma Diagnostics with Tracer-Encapsulated Solid Pellet
須藤滋 a、田村直樹 a、武藤貞嗣 a、尾崎哲 a、鈴木千尋 a、舟場久芳 a、村上泉 a、加藤太治 a、稲垣滋 b、居田克巳 a、LHD 実験グループ
Shigeru Sudo, Naoki Tamura, Sadatsugu Muto, Tetsuo Ozaki, Chihiro Suzuki, et al.
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核融合研、b九大NIFS, bKyushu Univ.

The diagnostic method of a tracer-encapsulated
solid pellet (TESPEL [1]) has been developed, since
the first TESPEL injection experiment was carriedout at CHS for the purpose of the impurity transport
study [2]. After the TESPEL injection experiments
at LHD started in 2000 [3], it has been found that
the TESPEL method is available for the various
diagnostic purposes. TESPEL consists ofpolystyrene as an outer layer and of specificmaterial as a tracer in the core. The TESPEL
diameter ranges 400 ~ 900 m, and amount of thetracer particles is typically ~ 1017 particles. This isless by a factor of 104 than the bulk plasma particles.
On the other hand, the amount of C and H particles
contained in the polystyrene shell with a diameterof 720 m is about 1×1019 particles for each. Thus,
when these ions are fully stripped, the total electron
number introduced by TESPEL contributes to thedensity increase of only 0.2×1019 m-3, which is still
smaller by a factor of more than 10 than the bulk
plasma density in case of the impurity transport
study.
The special features of TESPEL are: (a) the
local deposition of tracers inside the plasma ispossible, (b) the deposited amount of the tracer
inside the plasma can be known precisely, (c) arelatively wide selection of the tracer material ispossible, and (d) the flexibility due to a relatively
wide range of the size contributes to the variable
penetration depth. Owing to these advantages, thefollowing various studies have been carried out: (1)impurity transport, (2) thermal transport with non
local feature under certain condition, (3) highenergy particle observation with pellet charge
exchange method, (4) particle behavior inside themagnetic island O-point with intentionallyimplanted tracers by means of the TESPEL and (5)spectroscopic study with interested atoms containedin the core of the TESPEL. As for (1), the triple
tracers of V, Mn and Co are deposited by theTESPEL inside of the LHD plasma, andsimultaneously Ar supersonic gas puffing wasimplemented for simulating the impurities comingfrom the outside of the plasma as shown in Fig. 1.
In the medium density case (ne= 3-4×1019 m-3) it
was found that the Ar particles could penetrate into
the plasma core, while the tracers decayed in ~0.5 s[4] as shown in Fig. 2(a). In contrast, in the highdensity case (ne= 5-7×1019 m-3) it was found that the(a)(b)Fig. 1 FIR density for two density cases.

Fig. 2 K emissions from the tracers,
gas-puffed Ar and intrinsic Fe for (a) mediumand (b) high density cases.

Fig. 3 Schematic view of the impurity transport for(a) medium and (b) high density cases.

Ar particles were strongly suppressed, while thetracers were kept for a long time (no decay for theperiod of 1.5 s) as shown in Fig. 2(b). From theseresults, schematic view of the impurity transport forthe medium and high density cases is deduced asshown in Fig. 3. TESPEL injection into theintentionally produced magnetic island shows along impurity confinement inside the magneticisland as shown in Fig. 4 [5]. Also, significant
reduction of thermal transport is observed inside themagnetic island O-point [6] using the TESPELtechnique.
The local active fast neutral particle analyzer(NPA) using the pellet charge exchange (PCX)
method has a good spatial resolution as shown inFig. 5, where the resonance layer is changed for theICRF heating [7].
Owing to the feature of the flexibility of theFig. 4 (a) Tracer impurities were injected into themagnetic island with a TESPEL method. (b)Corresponding cross section of 2-D measurement oftracer emission with the AXUVD array systems.
Reconstructed images of the 2-D emission at (c) t= 1
ms and (d) t= 8 ms after TESPEL injection.

Fig. 5 Standard resonance layer case A and central
heating case B for ICRF are shown in (a). The case
A indicates more fast particle production as shownin (b) than the case B as shown in (b).

TESPEL size, a small pellet is used for non-local
transport study. Under a certain condition, the rapid
electron temperature increase in the plasma core
was observed, while the edge temperature wasdecreased [8].
Spectroscopy with interested atoms put as
tracer in TESPEL has been studied, especially in therange of EUV spectra from Sn, W, Gd and Nd [9]and the other heavy atoms. The recent achievementson the various subjects will be reviewed.
References
1. S. Sudo et al. Rev. Sci. Instrum. 83 (2012) 023503.
2. S. Sudo et al. 17th IAEA CN-69 EXP1/18 (1998).
3. N. Tamura et al. J. Plasma Fusion Res. SERIES 4442(2001).
4. S. Sudo et al. Plasma Phys. Control. Fusion 55(2013) 095014.
5. N. Tamura et al. J. Plasma Fusion Res. Series 8(2009) 0975.
6. S. Inagaki et al. Phys. Rev. Lett. 92(2004) 055002.
7. T. Ozaki et al. Rev. Sci. Instrum. 77(2006)10E917.
8. N. Tamura et al. Plasma of Phys. 12(2005)110705.
9. C. Suzuki et al J. Phys. B: At. Mol. Opt. Phys.
45(2012)135002.