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

自1982年发现h模以来，在环形等离子体中发现了许多由湍流输运分岔引起的结构，二十多年来的研究表明，电场剪切可以减少湍流和由此产生的输运，从而形成局部输运屏障，引起分岔结构。最近的模拟和理论研究表明，等离子体湍流可以通过雷诺应力产生宏观流动，宏观流动和微观湍流的相互作用会影响湍流的饱和水平和由此产生的输运。这可归因于以下原因：(1)纬向流不产生跨场输运与湍流之间存在准能量守恒定律；(2)纬向流随时间变化的剪切结构也减少了湍流。在CHS中，利用该资助构建的双重离子束探针，于2004年证明了层向流动的存在。这是世界上第一个成就。2005年进行了纬向流与湍流非线性联系的实验研究。实验成功地验证了纬向流与湍流非线性相互作用的存在。换句话说，准能量守恒定律是通过双重离子束探针的有效利用来证明的。纬向流现象在自然界中是普遍存在的。例子包括木星带和带、地球喷流、太阳倾斜等。该项目的成果将对宇宙中广泛观察到的湍流现象提供深刻的认识。

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.