Establishment Of Langmuir Probe Diagnostic System For J-TEXT Divertor Target

Fusion energy is an inexhaustible source of clean energy.The engineering and physical problems to be overcome in magnetic confined thermonuclear fusion devices are mainly the interaction between the plasma and the wall,including energy output,material protection,and so on.As one of the key components of modern Tokamak devices and future fusion reactors.The divertor can control the energy and impurity level,then cleans the main plasma.Therefore,it plays a significant role in modern fusion devices.This paper mainly introduces the characteristics of the J-TEXT Tokamak divertor configurations and the establishment of the probe diagnostic system applied in the divertor target.The physical experiment analysis and summary will also be discussed.The strike points of J-TEXT Tokamak are distributed in the high-field side and are generated by three sets of coils.The Tokamak can work under single null(SN),double null(DN),upper and lower single null(BSN)configurations with different discharge conditions.This paper mainly studies the plasma behaviors in the J-TEXT divertor target plates under ohmic discharge condition.The purpose is achieved by designing probe system in the target plates.The probe diagnostic system includes: measurement part,signal transmission part with data acquisition system.Some factors are considered include: the probe selection,distribution,signal transmission,installation and disassembly of the target probes,and other issues.Finally,using three probe sets to obtain plasma parameters at the target plates under divertor configurations is determined.The probe signals are connected to the measurement part through the cable,and finally uploaded to the data acquisition system.In the experiment of the divertor configuration.The evolution relationship about some physical parameters includes the temperature,density,float potential and ion saturation current are presented by probe system.It is found that there exists a large asymmetry under the single null configuration.which is mainly reflected in the upper and lower strike points.The ratio of the striking energy in the upper and lower SOL areas is distributed between 1.7-1.8.It can also be calculated that about 50% of the energy deposited in the surface of the target plates by integrating the heat flux in the poloidal and toroidal directions.Analyzing the eexponential decay length,the effective area of the SOL is also estimated.At present,Huazhong University of Science and Technology has designed a magnetic compression field reversed configuration(FRC)device to observe the plasma formation progress and other physical behavior in the HFRC device,which will provide important scientific value.HFRC is mainly composed of the FRC formation area at the both ends and the collision part in the middle region.The plasma is sprayed into the formation area,formed a field reversed plasma under θ-pinch.Finally,the high-performance plasma will be generated in the center collision area.This paper will introduce the necessity of building an interventional probe diagnostic system in the vacuum chamber of the formation area,the detailed design procedure of the probe drive system will be introduced.