رانش جريان امواج هيبريدي پايين در توكامك كروي MAST

چكيده انگليسي :

Lower Hybrid Current Drive in MAST Spherical Tokamak Nooshin Dashtban Shahrezaee n dashtbanshahrezaee@ph iut ac ir Date of Submission 29 02 2012 Department of Physics Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Akbar Parvazian parvazin@cc iut ac ir AbstractIt is usually recognized that a considerable amount of heating power additional to the ohmic heatingwill be required to reach ignition in a tokamak reactor To this purpose we use the method of theinjection of wave In the large tokamaks poloidal magnetic field is ignorable versus toroidal magneticfield Since toroidal magnetic field is very large we can use cyclotron waves to heat plasma In recent years there has been considerable interest in generating steady state currents in a plasmawith rf waves In particular it was predicted that these currents could be efficiently generated bywaves whose phase velocities are several times the electron thermal speed This prediction has beenconfirmed by numerous experiments in which the current was driven by lower hybrid waves TheLower Hybrid is the combination ion and electron cyclotron frequency resonance with wavefrequencies in the 1 GHz to 8 GHz range These results allow us to contemplate a steady statetokamak reactor in which the toroidal current is driven by lower hybrid waves Current drive refers tothe production of toroidal electric in a plasma torus that is current that encircles the torus hole Theintended use of this current is to enable a tokamak fusion reactor to operate continuously The method known as Lower Hybrid Current Drive LHCD provides waves with a hybrid frequencythat although it possesses an inefficient heating effect it can drive electric current thanks to the factthat it has an electric component parallel to magnetic field lines The power provided by this methodis around 10MW and is one of the most used methods in the control of the plasma during the fusionprocess The lower hybrid wave may transfer its energy to electrons by Landau damping leading toacceleration of the electrons motion at the direction along with the wave vector additional electricalcurrent is thus driven For LH waves momentum is transferred from the wave to the fast electrons inthe plasma at the resonance condition This process is studied by numerically solving the Fokker Planck equation with an added quasi linear term to solve this equation take the plasma then to beazimuthally symmetric about the magnetic field and homogeneous the Fokker planck equation thenreduces to an equation in time and two velocity dimensions We have used LSC code to solve the Fokker Planck equation and simulate the lower hybrid wavesinjected The Lower hybrid Simulation Code LSC is a computational model of lower hybrid currentdrive in the presence of an electric field Heating of electrons and ions is also computed Details ofgeometry plasma profiles and circuit equations are treated Two dimensional velocity space effectsare approximated in a one dimensional Fokker Planck treatment In this project simulation ofinjected lower hybrid waves for NSTX MAST PLT and TFTR tokamaks have been performed Theresults of this project show that spherical torus have better performance than torque tokamaks Thiscondition causes the fusion reaction self sustaining realized should be better than the possibility ofnuclear fusion power and performance is provided Key wordsLower hybrid waves LH Fokker Planck equation LSC code NSTX MAST TFTR and PLTtokamaks

دشتبان شهرضايي، نوشين

رانش جريان امواج هيبريدي پايين در توكامك كروي MAST

برنامه محاسباتي LSC , معادله فاكر-پلانك , PLT و TFTR