Studies of structure and dynamics of toroidal plasma using twin heavy ion beam probes

自1982年发现H模以来，人们在环形等离子体中发现了许多由湍流输运分叉引起的结构。二十多年来的研究表明，电场剪切可以减弱湍流和由此产生的输运，形成局部输运势垒，并导致分叉结构的产生。最近的模拟和理论认为，等离子体湍流可以通过雷诺应力产生宏观流动，宏观尺度流动和微观尺度湍流之间的相互作用可以影响湍流的饱和水平和由此产生的输运。这是由于：（1）准能量守恒定律适用于无交叉场输运的纬向流与湍流之间的关系;（2）纬向流的时变剪切结构也降低了湍流。在CHS中，使用在该补助金帮助下建造的双重离子束探针，于2004年证明了纬向流的存在。这是世界上第一个成就。此外，在2005年进行了实验，以证明纬向流和湍流之间的非线性联系。实验成功地验证了这种非线性的纬向流和湍流之间的相互作用。换句话说，利用双重离子束探针的有效使用证明了准能量守恒定律。带状流现象在自然界中普遍存在。该项目的成果将使人们对宇宙中广泛观测到的湍流现象有更深的认识。

Since 1982 when H-mode was discovered, a number of structures caused by bifurcation in turbulence transport have been found in toroidal plasma The researchover twenty years has shown that electric field shear can reduce the turbulence and resultant transport to form the local transport barrier and cause the bifurcated structures.Recent simulation and theories expect that the plasma turbulence can generate macroscopic flow through Reynolds stress, and the interaction between macro-scale flow and micro-scale turbulence can affect the saturation level of turbulence and the resultant transport. This is ascribed to the following reasons ; (1)a quasi-energy conservation law is valid for the relation between zonal flow to cause no cross-field transport and turbulence, (2)the time-dependent shear structure of zonal flow also reduces the turbulence. In CHS, using twin heavy ion beam probes constructed with help of this grant-in-aid, the existence of zonal flow was proven in 2004. This is the first achievement in the world. Further more, in 2005 the experiment to prove the nonlinear linkage between zonal flow and turbulence was performed. The experiment successfully verified the existence of such nonlinear interaction between zonal flow and turbulence. In other words, the quasi-energy conservation law was proven using the efficient use of the twin heavy ion beam probes.The phenomena of zonal flow are ubiquitous in nature. The example includes Jovian belt and zones, terrestrial jet stream, solar tacocline and so on. The achievement of this project should give deep insight to the turbulence phenomena widely observed in the universe.