| Due to the advantages of complete axisymmetrical structure,good confinement for plasma,no serious instability and high energy utilization efficiency,field reversed configuration(FRC)has unique advantages and bright prospects in magnetic confinement fusion.Therefore,it is of great significance to carry out the research on FRC device.Huazhong University of Science and Technology has built the first domestic experimental device(HFRC device)based on formation,collision-merging and magnetic compression.At first,an experimental device(HFRC-F device)which is the key component of the HFRC device has been built to study the formation process of FRC.As the basic system of the device,the quasi-steady system is very important for the stable operation of the devices.This article mainly works on the design of quasi-steady coils and theirs power supply in the device.In addition to the general design such as electromagnetic parameters,temperature rise and structure stress,the analysis of shielding and insulation are the specialness and emphasis.For the design of power supply,the corresponding schemes should be made according to the characteristics of the coils.According to the requirement for the magnetic field in the HFRC device,a total of twenty quasi-steady coils are set.Among them,fourteen quasi-steady coils with 52 k A ampere-turns and two quasi-steady coils with 200 k A ampere-turns are used to provide 0.1 T and 0.3 T backround magnetic mirror configuration.The remaining four quasi-steady coils are currently placed in the HFRC-F device to form the cusp magnetic field to assist in the formation of FRC plasma,which can provide 0.64 T magnetic field with 200 k A ampere-turns.Different engineering schemes are designed according to the characteristics of the coils which are reasonable and reliable,and the calibrations of temperature and stress are all within the allowable range.The coaxial structure coil systems in the two devices are the combination of high frequency with low frequency or direct current and large current with small current.High induced voltage is bound to be generated in the quasi-steady coils,which will cause damage to insulation and have a great impact on the quasi-steady magnetic field,so that shielding measures must be taken.The effects of external electromagnetic fields is mainly restrained by the eddy currents inside the shielding layer.In the HFRC device,the quasi-steady coils are placed in 6 mm aluminum shielding layer,which can effectively reduce the induced voltage to less than 30 V.While the quasi-steady coils in the HFRC device are placed in 8 mm stainless steel shielding layer and the induced voltage is reduced to less than 200 V.The shielding can effectively reduce the inductive voltage of the quasi-steady coils,however,it will affect the establishment of the quasi-steady magnetic field,further affect the design of the power supply.Therefore,the power supply schemes are different under different shielding schemes.The scheme based on three phase rectifier,power factor correction and DC/DC conversion is implemented in the HFRC device.The maximum output current is 0.6k A and 1.6k A.The quasi-steady coils in the HFRC-F device are powered by two sets of 1 k V/0.12 F capacitors and two sets of 1 k V/0.02 F capacitors,which can provide maximum current of4.63 k A and 5.79 k A respectively.After the construction of the quasi-steady coil-power system is completed,the debugging parameters can all reach the design index and the attenuation rate of the actual amplitude of the quasi-steady magnetic field is less than 5 % compared with the simulation value measured by the magnetic field distribution measurement experimental platform.At present,the quasi-steady system in the HFRC-F device is in good condition.Through the progress of design,construction and debugging for quasi-steady system in the HFRC-F device,a solid foundation has been laid for the follow-up work of the quasi-steady system in the HFRC device. |
PDF Full Text Request