Magnetic Field Measurement Technology Research And System Operation Of The Superconducting Magnet Of J-TEXT ECRH System

The purpose of magnetic confinement fusion research is to achieve plasma self-sustaining combustion by heating and charging. Due to plasma resistivity decreases with temperature 3/2 power, the ohmic heating could not heat the plasma temperature to 10 ke V order of magnitude that fusion reaction required. Raising plasma temperature by auxiliary heating is a necessary ignition condition for the device of the magnetic confinement fusion. Because of its good local heating and high coupling efficiency, Electron cyclotron resonance heating(ECRH) is widely used in the research of the magnetic confinement fusion device.In order to develop physics experiment research of plasma in J-TEXT, fusion and plasma research institute of Huazhong university of science and technology introduced 6 units of 200 k W power ECRH system from the Culham Science Center in 2013, and has started the reconstruction of the system in 2014. As an important part of ECRH system, superconducting magnet mainly provides the magnetic field configuration for gyrotron which is the wave source of ECRH system. The distribution and the stability of magnetic field has significant impact on the efficiency and safe operation of gyrotron. So, the superconducting magnet was an important part of the reconstruction of ECRH system. The main job of this article was the recovery, debugging and magnetic field measurement of the superconducting magnet of J-TEXT ECRH system, and accumulating construction and operation experience for the long-term operation of ECRH system.There are mainly three parts in this article.In the first part, the superconducting magnet and ECRH system of J-TEXT device were brief introduced. ECRH system was mainly introduced by the wave source gyrotron, transmission line and antenna system. The superconducting magnet was mainly introduced by cryostat, coils, power supply and protection control system.In the second part, the superconducting magnet of J-TEXT ECRH system has also been debugged before the magnetic field distribution was measured. The vacuum test of magnet, power supply test, cooling test and excitation test were introduced in detail.In the third part, according to the demands for magnetic field configuration of J-TEXT ECRH gyrotron and the structure characteristics of superconducting magnet, a magnetic field distribution measuring tool which could be precisely positioned of the three-dimensional coordinates was designed. The longitudinal magnetic field distribution, the radial magnetic field distribution and stray field distribution of the superconducting magnet have been measured through this tool. Through contrast of the measuring results, theoretical analysis and the simulation results of magnetic field distribution, the feasibility of magnetic field measuring method and the accuracy of magnetic field distribution measurement were verified. According to the superconducting magnet factory data, we could judge that the running state of the superconducting magnet was good; the magnetic field distribution could meet the operation requirements of gyrotron, the original intention of this article was achieved.