بررسي و شبيه سازي روش هاي تبديل مد در توليد امواج برنشتاين الكتروني براي گرمايش پلاسماي همجوشي

چكيده انگليسي :

159 بي IUT 77142Degree PhDTitle Study and simulation of mode conversion methods used for electron Bernstein wave generationin fusion plasma heatingAuthor Mohammad Ali AsgarianSupervisor Akbar ParvazianDepartment PhysicsDate April 16 2014Language PersianAbstract Nonlinear effects observed in inhomogeneous plasmas are simulated using different methods Particlein cell PIC method is used to simulate the conversion processes of electromagnetic modes used inheating the fusion energy equipment Firstly we tried to simulate conversion processes using Vlasovsolver method but due to problems of parallel processing and wave creation PIC method was used However Vlasov solver method has been used to simulate the electrostatic and electromagnetic effectsin a plasma with the characteristics of space plasmas Vlasov solver is the method in which to study the motion of particles the particle distribution functioncan be used Vlasov equation is coupled with Maxwell s equations and their time evolution iscalculated By Fourier transformation of velocity in the distribution function in the Vlasov equation andremoving the highest Fourier component via absorbing boundary conditions the recurrence effect isstrongly reduced Particles distribution functions and electric and magnetic fields are discretized on theorthogonal grid of equal sized cells in the position and inverted velocity Their time evolution isevaluated using Runge Kutta method A series of electrostatic effects are simulated using Vlasov solver method Firstly the electrostaticelectron Bernstein waves in a two dimensional space is simulated Then the famous Bernstein Landauparadox about the propagation and damping of electrostatic waves in magnetized and non magnetizedplasma has been investigated Finally the undamped Bernstein Greene Kruskal BGK modes due tononlinear evolution of Langmuir electrostatic wave have been obtained Also using this method anelectromagnetic X mode wave in a magnetized plasma with the properties of space plasma issimulated In PIC method position and velocity of particles are defined in continuous space and fields in discretespace Values of particles properties and fields are obtained sequentially at different times this processstarts from the initial conditions To obtain these values the relativistic Lorentz equation of motion issolved to obtain the position and velocity of particles along with Maxwell s equations for the fields Ordinary extraordinary Bernstein OXB double mode conversion is investigated and simulated withusing XOOPIC code in the TJ II stellarator for the case when the input wave frequency is 28 GHz Toprovide the conditions of TJ II nonuniform density and magnetic field profile is fully modeled Thefirst step of double conversion the OX mode conversion is observed By considering the componentsof the injected wave into the TJ II and the reflected wave from UHR layer we can easily identify Oinjection direction and the toroidal magnetic field of stellarator is 47 The obtained value is 63 and X mode waves Then by checking the electrical power of the injected and reflected O mode wave the O X mode conversion efficiency is obtained for the special case in which the angle between thewhich is consistent with the results obtained using other simulation methods and also withincoming wave is 10 and frequency 15 GHz is also investigated and simulated With this rangeexperimental results Direct X B mode conversion in NSTX by using XOOPIC in the case where the amplitude of theof input wave amplitude the system is at nonlinear regime It has been shown that the values obtainedfrom the simulation are higher than theoretical values about 10 to 15 This difference could be due tononlinear effects Keywords 1 Fusion Plasma Heating 2 Paricle in Cell 3 Vlasov Solver 4 Mode Conversion 5 Nonlinear Effects 6 Inhomogeneous Plasma

علي عسگريان، محمد

بررسي و شبيه سازي روش هاي تبديل مد در توليد امواج برنشتاين الكتروني براي گرمايش پلاسماي همجوشي

ذره در جعبه , حل ولاسوف-ماكسول , اثرات غير خطي , پلاسماي ناهمگن