Experimental simulation of high temperature plasma confinement using dimensionally similar low temperature plasma

使用尺寸相似的低温等离子体进行高温等离子体约束的实验模拟

• 批准号: 15206107
• 负责人: TOI Kazuo
• 金额: $ 21.63万
• 依托单位: National Institute for Fusion Science
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15206107/
• 关键词: plasma and nuclear fusion; dimensional similarity; turbulent transport; over-dense plasma; electron Bernstein wave heating; whistler wave heating; neoclassical transport; transport barrier; 電子バ-シュタイン波加熱; 閉じ込め改善; 次元的相似プラズマ; ヘリカル装置; 径電場; 電子バーンシ

Better understanding of transport phenomena such as transport barrier formation in high temperature plasma is a key issue for realization of fusion-burn plasma. However, the phenomena are very complex and the understanding is still preliminary. The main reason is difficulty to measure various plasma parameters and turbulent fluctuations with high time and spatial resolutions. To resolve this difficulty, this project aims at simulating transport in high temperature plasma using "dimensionally similar" low temperature plasma where several dimensionless parameters such as normalized collision frequency, plasma toroidal beta and so on are the same as those in high temperature plasma, except normalized ion gyro radius evaluated with electron temperature. In the low temperature plasma, Langmuir probes can be applied for measurements of equilibrium plasma parameters, fluctuations and correlations among various fluctuations with high time and spatial resolutions. This experiment was carried ou … More t in a small sized heliotron/torsatronl device CHS, having two main research objectives : (1) to produce and heat low temperature and density plasmas at low toroidal field condition by launching 2.45GHz electron cyclotron waves (ECWs), and (2) to measure electrostatic fluctuations in this low temperature plasma and clarify turbulent plasma transport. (1) : Plasma production was performed by 2.45GHz ECW launching in the range of the toroidal field from 175 G to 1050 G Over-dense plasmas exceeding the cut-off density for ordinary mode (O-mode) were successfully and routinely generated. In these over-dense plasmas, collisionality regimes of MHD (collisional), plateau and 1/v-regimes were realized over a substantial fraction of a plasma minor radius. This plasma production and heating is thought to be done by electron Bernstein waves (EBWs) converted from launched ECWs. Power absorption profile measured with ECW power modulation technique is concentrated in interior region beyond X-mode cutoff and upper-hybrid layers. This result is consistent with mode-converted EBW heating. (2): When launching microwave power exceeds a certain threshold, electron density profile exhibits a clear transition to a very peaked profile having steep gradient from a usual parabolic one. This indicates formation of internal particle transport barrier. As a new trial, we attempted to heat up a plasma by ramping ECW power from very low(~1kW) to high power (~20kW). In the initial phase with very low heating power, turbulent particle flux is very low but quickly increases toward strongly turbulent state with the increase in WCW power. However, turbulent particle flux immediately saturates at a certain level. With the increase in turbulent particle flux, fluctuations of radial electric field grow clearly, suggesting generation of sheared poloidal flow. Detailed analysis is under way.In parallel to these researches, we also studied characteristics of edge transport barrier formed in high temperature plasmas in CHS and the large helical device LHD. These results support the progress of this project. Less

更好地了解运输现象，例如高温等离子体中的传输屏障形成，是实现融合燃烧等离子体的关键问题。但是，现象非常复杂，理解仍然是初步的。主要原因很难以较高的时间和空间分辨率来测量各种血浆参数和湍流波动。为了解决这一难度，该项目旨在使用“尺寸相似”的低温等离子体模拟高温血浆中的传输，其中几个无量纲参数（例如归一化碰撞频率），等离子体的环形β等与高温等离子体中的血浆相同，除归一化的离子Gyro Radius与电子温度相同。在低温血浆中，可以将Langmuir问题用于测量平衡等离子体参数，各种波动之间具有较高时间和空间分辨率之间的波动和相关性。该实验是在小型的Heliotron/Torsatronl设备CHS中进行的，具有两个主要的研究目标：（1）通过在低环形场状态下生产和热量低温和密度等离子体，通过启动2.45GHz电子环旋转（ECWS）（ECWS）以及（2），（2）在此低温和Clari Plastmam中测量静电率的运输。 （1）：在2.45GHz ECW发射的范围内，在175 g到1050 g的超密度等离子体的范围内进行了血浆产生，超过了普通模式（O模式）的截止密度，并逐渐生成。在这些过度密集的等离子体中，MHD（碰撞），高原和1/V-Legimes的碰撞状态在大量的等离子小径上实现了。该血浆产生和加热被认为是由从发射的ECWS转化的电子伯恩斯坦波（EBW）完成的。通过ECW功率调制技术测量的功率抽象轮廓集中在X模式截止和上层层以外的内部区域。该结果与模式转换的EBW加热一致。 （2）：当发射微波功率超过一定阈值时，电子密度轮廓表现出明确的过渡到非常峰值的剖面，并具有从通常的抛物线寄生虫中的钢梯度。这表明形成了内部颗粒传输屏障。作为一项新试验，我们试图通过将ECW功率从非常低（〜1kW）提高到高功率（〜20kW）来加热等离子体。在具有非常低的加热功率的初始阶段，湍流的粒子通量非常低，但随着WCW功率的增加，湍流迅速朝着强烈的湍流状态增加。但是，湍流通量立即在一定水平上饱和。随着湍流的增加，径向电场生长的波动明显，表明剪切的螺状流动产生。在与这些研究的同时，我们还研究了在CHS中高温等离子体和大型螺旋装置LHD中形成的边缘传输屏障的特征。这些结果支持该项目的进展。较少的

项目成果

Two-Dimensional Measurement of Electron Density in LHD plasmas by Sheet-Shaped Thermal Lithium Beam

利用片状热锂束二维测量 LHD 等离子体中的电子密度

• 发表时间: 2006
• 期刊: Journal of the Korean Physical Society 49・1
• 作者: T.Takahashi;T.Morisaki;K.Toi
• 通讯作者: K.Toi

Experimental Simulation of High Temperature Plasma Transport Using Almost Dimensionally Similar Cold Plasmas in the Compact Helical System

在紧凑螺旋系统中使用几乎尺寸相似的冷等离子体进行高温等离子体输运的实验模拟

• 发表时间: 2005
• 期刊: Journal of plasma and fusion research SERIES Vol.6(to be published)
• 作者: K.Toi;R.Ikeda;M.Takeuch;T.Ito;C.Suzuki et al.
• 通讯作者: C.Suzuki et al.

Production of Over-Dense Plasmas by Launching 2.45GHz Electron Cyclotron Wave in the Compact Helical System

通过在紧凑螺旋系统中发射 2.45GHz 电子回旋波来产生过密等离子体

• 发表时间: 2006
• 期刊: Journal of the Korean Physical Society 49・1
• 作者: R.Ikeda;M.Takeuchi;K.Toi;C.Suzuki;S.Okamura
• 通讯作者: S.Okamura

Characteristic Formation of Edge Transport Barrier in the Compact Helical System

紧凑螺旋系统中边缘传输势垒的特征形成

• 发表时间: 2006
• 期刊: Journal of Plasma and Fusion Research 1・2
• 作者: M.Takeuchi;K.Toi;K.Nagaoka;C.Suzuki;T.Minami et al.
• 通讯作者: T.Minami et al.

Production of Over-Dense Plasmas by Launching of 2.45GHz Electron Cyclotron Waves on the Compact Helical System

通过在紧凑螺旋系统上发射 2.45GHz 电子回旋波来产生过密等离子体

• 发表时间: 2005
• 期刊: Journal of Plasma and Fusion Research 81・7
• 作者: R.Ikeda et al.