Effects of toroidal rotation shear and magnetic shear on thermal and particle transport in plasmas with electron cyclotron heating on JT-60U
Effects of toroidal rotation shear and magnetic shear on thermal and particle transport in plasmas with electron cyclotron heating on JT-60U
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DOI：
10.1088/0029-5515/55/7/073014
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发表时间：
2015-06
期刊：
影响因子：
3.3
通讯作者：
M. Yoshida;M. Honda;E. Narita;N. Hayashi;H. Urano;M. Nakata;N. Miyato;H. Takenaga;S. Ide;Y. Kamada
中科院分区：
文献类型：
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作者：
M. Yoshida;M. Honda;E. Narita;N. Hayashi;H. Urano;M. Nakata;N. Miyato;H. Takenaga;S. Ide;Y. Kamada
在许多托卡马克中观察到的电子回旋加热 (ECH) 带来的热和粒子输运的增加可能是建立电子加热 ITER 运行场景的关键问题。为了解决这些问题，在离子通道中具有内部传输势垒的正磁剪切、弱磁剪切 (WS) 和反向磁剪切等离子体中，对 ECH 热和粒子传输不增加的条件进行了实验研究。当在 ECH 之前形成大的负环形旋转剪切 (|dVφ/dr| > 4 × 105 s−1) 时，离子温度下内部传输势垒周围的离子热扩散率 (χi) 与 ECH 保持恒定。另一方面，当环形旋转剪切较小或为正时，χi 增大。这些特性不依赖于磁剪切、电子与离子温度比 (Te/Ti) 和 ECH 功率。当磁剪切为负时，电子热扩散率与 ECH 保持恒定。在负磁剪切条件下，ECH 过程中有效粒子传输保持恒定或减少。观察表明，电子通道维持不存在负磁剪切阈值或非常小；在 WS 操作中，ECH 期间保持电子热和粒子限制，并具有小的负磁剪切。
Increases in thermal and particle transport with electron cyclotron heating (ECH) that are observed in many tokamaks can be a critical issue in establishing ITER operational scenarios with electron heating. To address the issues, conditions with no increase in the thermal and particle transport with ECH have been experimentally investigated in positive magnetic shear, weak magnetic shear (WS) and reversed magnetic shear plasmas with internal transport barrier in the ion channel. The ion heat diffusivity (χi) around the internal transport barrier in the ion temperature remains constant with ECH when a large negative toroidal rotation shear (|dVφ/dr| > 4 × 105 s−1) is formed before the ECH. On the other hand, χi increases on the condition that the toroidal rotation shear is small or positive. The characteristics do not depend on magnetic shear, the electron to ion temperature ratio (Te/Ti) and ECH power. The electron heat diffusivity stays constant with ECH when the magnetic shear is negative. Effective particle transport remains constant or reduces during ECH under the condition of negative magnetic shear. An observation indicates that there is no threshold of the negative magnetic shear or a very small one for the electron channel sustainment; the electron thermal and particle confinement is maintained during ECH with a small negative magnetic shear in the WS operation.