| The electromagnetic environment aroud the J-TEXT device is very complex,diagnosis and control signals are badly interfered,the fine physical experiments are affected.In order to improve the situation of electromagnetic interference,this paper tries to build interference models and analyze the quantitative relationship between the interference source and the interference signal,to put forward improving measures through quantitatively analyzing of the interference mechanism.Effective working frequency of most diagnosis signals on J-TEXT device is below 1 MHz,and the strongest jamming signal is also under MHz,so this kind of interference belongs to the near-field interference.Research idea of this paper is to separate the electric field and magnetic field,and then build the equivalent circuit models and studied respectively.Difficulty of the research is analysis of the coupling capacitance and coupling inductance between interference sources and the circuits being interfered in the complicated tokamak device.Therefore,this paper simplifies the problem,and then establish an electric field platform and a magnetic field platform,and test the performance of the diagnosis circuits on the platforms of the electric field and magnetic field,and compared with premeditation circuit interference model,verify and correct the models,in the same time,measure and analyze sensitivity of diagnosis circuits under the electric field and magnetic field interference.To produce high voltage without current as the electric field interference sources,this paper adopts a high frequency transformer to boost voltage.To produce large current with low voltage as the magnetic field interference sources,this paper adopts a power amplifier to supply a coil.In order to measure the intensity of electric field and magnetic field interference on the platform,this paper also designs a kind of electric field probe and magnetic field probe,the shielding structure of magnetic field probe is designed to shield electric field,the magnetic probe is almost not influenced by electric field interference.On this basis,this paper uses electric interference platform and magnetic interference platform to test a typical J-TEXT diagnosis line,and then studies the characteristics of the interference,the test results showed that the circuit is more vulnerable under the electric field interference,and the photoelectric detector itself is not easily disturbed,and the signal transmission lines between the detector and the amplifier are susceptible to interference.The research of this paper has made preparation for J-TEXT electromagnetic compatibility upgrade,the research method can also be applied to other kinds of electromagnetic interference researches beyond the J-TEXT. |
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