Research on transport barrier and two-fluid relaxation phenomenon based on radial electric field caused by an orbit loss of high energy electrons

基于高能电子轨道损失引起的径向电场的输运势垒和二流体弛豫现象研究

• 批准号: 15340197
• 负责人: OGAWA Yuichi
• 金额: $ 10.5万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-15340197/
• 关键词: High temperature plasma; Ultra-high beta; Two-fluid relaxation theory; High temperature superconducting coil; Magnetic levitation; Electron cyclotron resonance; Electron Bernstein Wave; Mode conversion; 超高ベータプラズマ; 内部導体装置; 磁気浮上コイル; 高温超伝導線材; 電子サ

We are exploring ultra-high beta plasmas based on two-fluid relaxation theory proposed by Mahajan-Yoshida with an internal coild device Mini-RT, where the plasma is produced by 2.45 GHz microwave. The cut-off density of 2.45 GHz electromagnetic microwave is limited up to 7.4x10^<16> m^<-3>. Here we have considered to introduce an Electron Bernstein Wave (EBW) in order to overcome this density limit, because EBW has no constraint on the plasma density for wave propagation. We are studying an excitation of EBW through the mode-converstion from X-mode launched from the weak-field side.Up to now, in floating coil experiments, we have achieved the plasma density of 1.5x10^<17> m^<-3>, which is about 2 times higher than the cut-off density. To realize a mode conversion to EBW from X-mode efficiently, the steep density gradient should be prerequisite ; i.e., theory predicts that the product of the density scale length and the magnetic field strength should be 5x10^<-4> Tm. This means that the density scale length should be less than 1 cm in the Mini-RT case. We have therefore introduced the steep density gradient at the separatrix region, which is produced by the combination of the floating and levitation coils.There appears many higher harmonics of the electron cyclotron resonance in the internal coil device, because the field strength of the dipole magnetic field is rapidly decaying ; i.e., B 〜 R^<-3>. In addition, the mode-conversion takes place at the upper hybrid resonance region, which is sensitive to the plasma density. This might introduce the feasibility of heating profile control, by changing the position of the upper hybrid resonance region. Our preliminary experimental results show that the radial position of electron heating moves according to the change of the plasma density. These results might be useful for exploring ultra-high beta plasmas in the internal coil device.

我们正在探索基于Mahajan-Yoshida提出的双流体弛豫理论的超高β等离子体，利用内部冷装置Mini-RT，等离子体由2.45 GHz微波产生。2.45 GHz电磁微波的截止密度被限制在7.4 × 10^<16> m^<-3>。为了克服这种密度限制，我们考虑引入电子伯恩斯坦波（EBW），因为EBW对波传播的等离子体密度没有限制。我们正在研究从弱场侧发射的x模通过模式转换激发EBW的方法。到目前为止，在浮圈实验中，我们已经实现了1.5 × 10^<17> m^<-3>的等离子体密度，比截止密度高出约2倍。为了有效地实现从x模到EBW的模式转换，必须以陡峭的密度梯度为前提；即理论预测密度标度长度与磁场强度的乘积应为5 × 10^<-4> Tm。这意味着在Mini-RT病例中，密度标度长度应小于1cm。因此，我们在分离矩阵区域引入了陡峭的密度梯度，这是由浮动线圈和悬浮线圈结合产生的。由于偶极磁场的场强在快速衰减，内部线圈装置中电子回旋共振出现了许多高次谐波；即B ~ R^<-3>。此外，模式转换发生在对等离子体密度敏感的上部混合共振区。这可能会引入通过改变上部混合谐振区的位置来控制加热剖面的可行性。初步实验结果表明，电子加热的径向位置随等离子体密度的变化而变化。这些结果可能有助于探索内部线圈装置中的超高等离子体。

项目成果

Mini-RT装置用高温超伝導磁気浮上コイルの冷却・励磁試験

Mini-RT设备高温超导磁悬浮线圈冷却及励磁测试

• 发表时间: 2004
• 期刊: 超伝導・低温工学会誌 39
• 作者: 柳 長門;森川惇二;三戸利行ら
• 通讯作者: 三戸利行ら

内部導体装置Mini-RTにおけるプラズマ生成と高温超伝導コイルの磁気浮上実験

内导体装置Mini-RT等离子体产生及高温超导线圈磁悬浮实验

• 发表时间: 2004
• 期刊: Journal of the Cryogenic Society of Japan 39巻5号
• 作者: 森川惇二;他
• 通讯作者: 他

Experiments of the HTS Floating Coil System in the Mini-RT Project

Mini-RT项目中高温超导浮动线圈系统的实验

• 发表时间: 2004
• 期刊: IEEE Transactions on Applied Superconductivity 14
• 作者: N.Yanagi;T.Mito;J.Morikawa;et al.
• 通讯作者: et al.

Experimental evaluation of loss generation in HTS coils under various conditions

• DOI: 10.1109/tasc.2005.849263
• 发表时间: 2005-06
• 期刊: IEEE Transactions on Applied Superconductivity
• 影响因子: 1.8
• 作者: T. Hemmi;N. Yanagi;K. Seo;R. Maekawa;K. Takahata;T. Mito

ECH Plasma Experiments on an Internal Coil Device with a High Temperature Superconductor Coil

高温超导线圈内部线圈装置的 ECH 等离子体实验

• 发表时间: 2005
• 期刊: Transactions of Fusion Science and Technology 47
• 作者: Y.Ogawa;J.Morikawa;K.Ohkuni;S.Yamakoshi;T.Goto;T.Mito;N.Yanagi;M.Iwakuma
• 通讯作者: M.Iwakuma