Solitons Driven By Ion Temperature Gradient With Regularized κ-distributed Electrons

In magnetic confinement plasmas,many microscopic instabilities can influence their particle and energy confinement properties.The main physical processes include magneto hydro dynamic instability,escaped electrons,impurity radiation,loss cone instability and anomalous transport of ions.The anomalous transport problem of ions has been an important theoretical challenge in tokamaks.However it is generally accepted that turbulence driven by ion temperature gradients is the main explanation for the anomalous transport.For this reason,the study of the properties of ion temperature gradient modes has always been an interesting issue.In this paper,the instability of ion temperature gradient and the soliton structure driven by ion temperature gradient in plasma with regularized κ-distributed electrons are investigated using the two-fluid model.Chapter 1,first,the origin and properties of plasma are introduced,and the research progress of ion temperature gradient mode is expounded.Secondly,the κ-distribution,regularized κ-distributed and two-fluid theory are introduced.Finally,the origin and development of nonlinear solitons are introduced.Chapter 2,The dispersion relation of the ion temperature gradient mode obtained on the basis of the local approximation shows that the growth rate of the ion temperature gradient mode decreases with the increase in the exponential cut-off parameterα,the ratio of ion density gradient scale length to ion temperature gradient scale lengthη_i and the ratio of electron temperature to ion temperatureτ.On the contrary,the ion temperature gradient mode increase with the increase of spectral indexκand the exponential cut-off parameterα.It indicates that the presence of the superthermal electron leads to destabilization of the ion temperature gradient mode.In addition,the effect of effective thermal velocityθon the growth rate of ion temperature gradient instability is also discussed.The results show that for the same model,different definitions of effective thermal velocity will have different results.Chapter 3,Firstly,the motion coordinates are introduced,and the Sagdeev pseudopotential equation is obtained by coordinate transformation.The existence range of soliton structure is obtained by analyzing the Sagdeev pseudopotential equation;the soliton structure is obtained by small amplitude approximation.The results show that the soliton amplitude increases with the increase in the exponential cut-off parameterαand the spectral indexκ,whereas the width of the soliton varies inversely.The existence range of the soliton is very small.Compared with exponential cut-off parameterα,the change of the spectral indexκhas a greater influence on the soliton structure.Finally,the work of this paper is summarized and the follow-up work of the article is prospected.