03pA08
LHD高Te放電の輸送解析および新古典輸送シミュレーションとの比較
Transport analysis of LHD high-Te discharge and comparison with neoclassicaltransport simulation
佐竹 真介，松岡 清吉1， 横山 雅之，PABLANT, Novimir A.2，LHD実験グループ
Shinsuke SATAKE, Seikichi MATSUOKA1, Masayuki YOKOYAMA, Novimir A. PABLANT2,and the LHD Experiment Group
核融合研，高度情報科学技術研究機構1，プリンストンプラズマ物理研2
NIFS, RIST1, PPPL2
In helical plasmas as in the Large Helical Device in NIFS, it is known that the ambipolar condition for theneoclassical ion and electron radial particle transport determines the radial electric field profile in the plasma.
To evaluate the ambipolar radial electric field, we have developed a neoclassical transport code
FORTEC-3D[1] which solves the drift-kinetic equation in 5D phase space by themethod. One of themain purpose of FORTEC-3D is to include the effect of finite drift motion perpendicular to the magnetic
field lines and flux surfaces, or finite-orbit-width effect, into the neoclassical transport calculation. The
finite-orbit-width effect is neglected in the other local transport codes such as GSRAKE and DGN/LHD.
FORTEC-3D was first applied for ion neoclassical transport calculations in LHD plasmas since it is expectedthat the finite-orbit-width effect is important for ions because of their large radial orbit width compared tothat of electrons. However, It is revealed that, in high-Te and low-collisionality LHD plasmas, the finiteand curvature drift across the magnetic field lines significantly affects the dependence of electron
neoclassical particle flux
on the radial electric field[2]. Therefore, to analyze the plasma particle andheat transport as well as to estimate the ambipolarin LHD high-Te discharges, it is important tocalculate bothandwith taking account of the finite-orbit-width effect.
FOTEC-3D can treat only one particle species at once. Therefore, in the previous studies we have solved
only either
orby FORTEC-3D, and the local calculation results for the other particle species to seek)= () on each flux surface. In the present study, a new way to estimate
the ambipolar condition (the ambipolar condition by using FORTEC-3D simulation both for ions and electrons is explained.
The other topic in the presentation is that the new ion temperature meausement method in LHD experiment.
High-Te discharge in LHD is usually obtained in ECH heated plasmas. The new X-ray imaging crystal
spectrometer (XICS) installed in LHD[3] enables us to measure the ion temperature as well as poloidal
rotation velocity, without NBIs. Using the observedandprofiles, we have conducted precise
neoclassical transport simulation for a LHD high-Te discharge. It is found that the ambipolaris positive(electron-root) in the core region (r<0.8) and is negative at near the plasma edge (r>0.8a). The magnitude oftherotation speed agrees with the poloidal rotation velocity from XICS measurement. Also,neoclassical radial energy flux is compared with the power balance analysis of the discharge. It is found thatat the electron-root core region, ion neoclassical energy flux is comparable to that is estimated from thepower balance, while electron neoclassical energy flux is by a factor 2 smaller than the power balance.
[1] S. Satake, et al., Plasma Fus. Res. 3 (2008) S1062.
[2] S. Matsuola et al., Phys. Plasmas 18 (2011) 032511.
[3] N. Pablant, et al. Rev Sci Istrum (2012)