Error Analysis Of Rogowski Coil In Tokamak Plasma Current Measurement

In Tokamak, the current measurement of plasma is very important since it is directlyrelated to calculate ohmic heating power and the basic discharge parameters such as safetyfactor and analysis of plasma instabilities. Rogowski coil due to its simple structure, easyto install, is the most common means of measurement of tokamak plasma current. Inactual use, the relative positional relationship between the Rogowski coil and the currentto be measured is not determined; at the same time, in order to avoid the diagnosiswindows, the coil is not perpendicular to the section of the plasma current, which maylead to errors when measuring Rogowski coil. The area that to line and return line to theRogowski coil surrounded is an important indicator of the ability of anti-interference inRogowski coil. In tokamak, Rogowski coil under a strong toroidal field environment, thiscircuit is easily inducing voltage in the effect of the magnetic flux of the toroidal field,thereby forming interference. According tokamak magnetic configuration and Rogowskicoil structure, analysing Rogowski coil measurement error systematically in tokamak hasan important practical significance.In this thesis, taking a group of PCB Rogowski coil installed outside the wall ofJ-TEXT tokamak vacuum for example, I analyze the current measurement error when theplasma current is in different positions in a vacuum chamber in detail. Since the coilinstalled at a position deviated from the plane of symmetry at a distance to avoid keystoneinsulating vacuum chamber, this paper analyzes the measurement error caused by theinstallation position deviation. Meanwhile, Rogowski coil deviating from the plane ofsymmetry, resulting magnetic flux in its toroidal field, forming the interference signalwhen the coil current changes in a toroidal field, the paper analyzes the characteristics andsize of the signal, and compares it with experimental waveform. The results shows that thetoroidal field coil currents cause significant impact on Rogowski coil in the fallingphases,and the analysis results agree with the experimental waveform. The results ofthis paper provides a reference to measure the accuracy of the J-TEXT current and new Rogowski coil design, while explaining the changes in current toroidal field coils is theplasma current waveform, but also provides a certain foundation to carry out a variablelongitudinal field experiment in future.