29D10P
ヘリオトロンJにおける	 
高時間分解能Nd:YAGトムソン散乱計測システムの構築	 
Construction of high time resolution Nd:YAG Thomson scattering system
in Heliotron J	 釼持	  尚輝1,	 南	  貴司2,	 荒井	  翔平1,	 高橋	  千尋3,	 小林	  進二2,	 水内	  亨2,	 	 
岡田	  浩之2,	 長崎	  百伸2,	 向井	  清史3,	 李	  炫庸1,	 臧 臨閣1,	 永榮	  蓉子1,	 沙	  夢雨1,	 	 
大谷	  芳明1,	 笠嶋	  慶純1,	 原田	  伴誉1,	 和多田	  泰士1,	 福島	  浩文1,	 杉本	  幸薫1,	 	 
中村	  雄一1,	 橋本	  絋平1,	 中村	  祐司1,	 山本	  聡2,	 木島	  滋2,	 大島	  慎介2,史	  楠2,	 
佐野	  史道2	 
N. Kenmochi1, T. Minami2, S. Arai1, C. Takahashi3, T. Mizuuchi2, et al.
京大エネ科1,	 京大エネ研2	 ,	 核融合研3
GSES Kyoto Univ.1, IAE Kyoto Univ.2, NIFS3
Moreover, an interrupt process of the PIC makes it
possible to control the laser timing precisely with
scattering of only several dozens of ns. In addition,
this timing controller can be used to increase thelaser power gradually for slow start-up by theprecise timing control between the Q-switch and theflash lamp, which is useful to protect opticalcomponents from unstable initial laser oscillations.
We have already completed the construction ofhigh time resolution system of laser controller andconfirmed its design performance. In the future, by
this system, the formation of transport barrier will
be demonstrated and the system will contribute to
the clarification of the relevant physics.
Signal#Power#[a.u.] Voltage#[V]

Time evolution of plasma profiles is
indispensable to clarify the physics of transportbarrier formation relating to so-called improved
confinement modes in magnetically confinedplasmas. In a helical-axis heliotron device,
Heliotron J, spontaneous transition to improved
confinement mode, which is similar to H-mode, hasbeen observed experimentally [1]. However, theexistence of transport barrier in this transition has
not been confirmed yet for the lack of detailed
electron density and temperature profiles. ANd:YAG Thomson scattering system has beendeveloped to obtain such profile data with high timeand spatial resolutions in Heliotron J. The system
has 25 measurement points with spatial resolutionof ~10 mm. Two Nd:YAG lasers of 500 mJ havebeen selected to obtain adequate signal intensity forthe profile measurement by considering typicalelectron densities of Heliotron J plasmas ( ￣ne =0.5-3×1019 m-3). Polychrometors with a set ofinterference filter are used to analyse the scattered
light spectra. The data acquisition system is a VME
based one that is operated under the Time Invariant
Method (TIM) with real-time operation capability[2].
Since transport barriers are usually formed
transiently during several hundreds of microseconds,
the laser oscillation timing has to be controlled withaccuracy sufficient for tracing the barrier formation.
For this purpose, a timing controller using a PIC
micro-controller has been developed. By using twolasers (> 500 mJ@50 Hz) and this control system,
we can widely control the effective time interval.
Figure 1 shows Q-switch signals and power signalsof each laser. The excitation timing of these twolasers is well controlled in the interval of 80 ns.

80#ns
Laser#1

Q:switch#signal#
Laser#1 Laser#2 from#PIC

Laser#2

80#ns

Laser#Power

Figure 1. Signals from controller and Power of oscillated lasers.

[1] F.Sano, et al., Nucl. Fusion (2005) 1557-1570[2] C.Takahashi, S.Okamura, K.Matsuoka, H.Iguchi,A.Ejiri, A.Fijisawa, K.Ida, T.Minami, et al.,About the Cinos of CHS Data Acquisition andAnalysis system. (in Japanese) Proc. Research
and Technical report (National Institute formolecular Science 2000.6) No.16, pp.85-87.