Design And Construction Of Field Reversed Configuration Pre-ionization Device Based On Rotating Magnetic Field

Field-Reversed Configuration(FRC)is a compact toroidal plasma confined by a polar magnetic field.It has a closed field line plasma region.In the theta-pinch method to form FRC,the?-direction oscillation method is generally used for pre-ionization.The pre-ionization PI branch and Main branch in the power supply topology are strongly coupled,and there is a contradiction that is difficult to reconcile between the power supply operating efficiency and the power supply operating parameters,thereby limiting the final FRC plasma formation parameters.One solution is to use a rotating magnetic field for pre-ionization,which can remove the PI branch and realize the decoupling of the pulse power supply ionization branch and the main field branch.The main content of this article is to study the ionization optimization effect of the rotating magnetic field on the FRC injected gas.For this purpose,a rotating magnetic field ionization experimental device HUST Rotating Magnetic Field(HRMF)is designed and built.This article mainly includes the following parts:The first part explains the advantages of controllable nuclear fusion energy relative to other energy sources.It introduces the field-reversed configuration plasma.Aiming at the formation of initial plasma in the early stage of FRC,the RMF was introduced,then discuss the application status of RMF in FRC research.Finally,the experimental difficulties of the RMF ionization experiment are analyzed.The second part introduces in detail the design of each part of the HRMF device development,including rotating magnetic field magnet power supply and its coil,quasi-steady state magnetic field magnet power supply and coil,hydrogen thyratron trigger system based on IGBT,vacuum system and pulse gas injection system.Two sets of high-voltage pulse power supplies respectively discharge two sets of high-voltage litz coils.The frequency of the discharge current is as high as 92 k Hz,the amplitude of the control current is equal,and the phase difference is 90°,thereby generating a transient rotating magnetic field.The high-voltage power switch adopts hydrogen thyratron,and the rotating magnetic field coils adopt high-voltage litz wire,which is used to overcome the skin effect of high-frequency current,thereby reducing the energy loss of the coils.The inductance and resistance of the rotating magnetic field coils are accurately calculated,and the energy output of the rotating magnetic field ionization coupling is analyzed and calculated.The quasi-stable coil is powered by 48electrolytic capacitors of 0.01 F in parallel,which can provide a background magnetic field with a magnetic field size of 500 G and a duration of 10 ms.In order to realize the pulse-controlled injection of gas,the solenoid valve drive circuit is designed,and the solenoid valve in series with the micro flowmeter can better control the amount of gas injected.The third part introduces the plasma diagnostic system supporting the rotating magnetic field ionization experimental device.First,the measurement methods and corresponding principles of single probe,double probe,triple probe and magnetic probe are explained.Finally,the design and production details of electrostatic three probe and three-dimensional magnetic probe are introduced in detail.The fourth part first introduces the operation control platform of the rotating magnetic field pre-ionization device,and then introduces the overall operation process of the device in detail.Finally,a preliminary rotating magnetic field ionization experiment was carried out on the HRMF device using argon gas,the plasma electron temperature generated by ionization is about10 e V and the electron density is on the order of 10¹⁷m^-3.