Research Of The Statistical Characteristic Of Blob Structure On Tokamak

Blob strctrues,or the filament strctures,are frequently being obsevered on the edge and scrape-off layer(SOL)region of Tokamak.The parameters such as the density and temperature of the sturcture,are much higher than the background parameter of the edge and SOL region.The eruption of the strucure is nonperiodic,they are likely to erupt in a rather short time.On the radial and poloidal direction,the scale of the filament could reach the order of milimeter or even centimeter while on the toroidal direction,the correlation length could reach the order of 10 meteres since the structure would expand along the magnetic field line.The lifetime of the filament is about tens to hunders microseconds,which is comparatively a long time.This strucure is considered to have the main contribution to the particle transportation in edge and SOL region.The radial transportation could transport the high denstiy and high tempreature plasma from the core region directily to the first wall of Tokamak,which would cause the erotion and damage of the first-wall.Moreover,the filament caused by the eruption of edge localized mode(ELM)called ELM-filament would take off a large amount of energy as well as particles from the core region.Due to these characteristics mentioned above,the International Thermonuclear Experimental Reactor(ITER),is now focus on the research of its characteristic as well as the way to mitigate or supperess the erubtion of the structure,especially the ELM-filament.In this thesis,we wil use several different Lagmiur probe equiped on HL-2A to obtain the data of blob and filament structure for analyzation.Use the conditional average(CA)method,we could obtain the charateristic siganal of a certain time period from the time-ordered raw data.By this way,we could obtain some basic statistical properties.Going further,we analyzed the data of several different type of probe arrays: by analyzing the 3 ? 3 stair-like probe array,we obtained the radial velocity-time evolution of the blobs that pass through the array,and a also probed that the poloidal gradiaent of temperature in edge region and SOL region is neglectable;by analyzing the 1 ? 12 poloidal linear array,we obtained the 2D profile of the filament structure,which the 2D means poloidal-radial,of the potential as well as the radial velocity.Finally,we combined the data of supersonic molecular beam injection(SMBI)with the probe data,to figure out the the fueling method's effect on ELM-filament.By comparing the statistical data of ELM-filament before and after fueling,we could judge the effect that how SMBI mitigate the ELM-filament.