Research On Inductively Coupled Coil Of Pulsed Intense Magnetic Field Generator

In recent years,with the continuous development of intense magnetic field device technology,there has been considerable interest in the research of magnetized laser plasma.These studies have applications in magnetic inertial confinement fusion,astrophysics and pulsed laser deposition.For example,in the field of inertial confinement fusion,a magnetic field can be applied to reduce energy loss during transportation and increase energy gain.In the field of astrophysics,the experiment of magnetized laser plasma proves that the large angle interstellar wind may be transformed into jet under the axial magnetization.In the industrial field,the optimization of pulsed laser deposition technology has also been realized by applying an external magnetic field.Pulsed intense magnetic field device is the core equipment of magnetized laser plasma experiment.Pulsed intense magnetic field device usually uses small single-turn coil or solenoid coil.The single-turn magnetic field coil occupies a small solid angle,which will not significantly interfere with the arrangement of the laser and detectors in the laser plasma experiment.So it is convenient for the arrangement of the experiment,but the inductance of single-turn coil is small,the energy utilization rate is low.The solenoid coil can concentrate most of the energy in the magnetic field coil,with high energy utilization.But the larger volume of the solenoid severely limits the flexibility of the experiment.Here an inductively coupled coil is developed to optimize the pulsed intense magnetic field device,which solves the problem of incompatibility between a small-volume single-turn magnetic field coil and high energy utilization.The inductively coupled coil couples the energy of the multi-turn solenoid to the single-turn magnetic field coil through the transformer,which increases the current density markedly.The multi-turn solenoid occupies a larger share of the system inductance,and the energy utilization rate is high.The single-turn magnetic field coil is small in size,which is convenient for experiment arrangement.It has a stronger magnetic field,which can meet the needs for many experiments.At the same time,the use of inductively coupled coil reduces the system's requirements for loop inductance,and the transmission line(connecting capacitors,switches and field coils)can be longer,which relaxes the requirements for system compactness and experimental environment.Through analysis,we find that the strongest magnetic field can be obtained on an optimal number of turns and diameter of the primary solenoid.And the magnetic field generated by the inductively coupled coil is mainly affected by the number of turns and the diameter of the primary solenoid.It is found that the magnetic field of the coil increases with the number of turns and diameter growth at the beginning.However if the number of turns or the diameter is too large,the magnetic field will bacame lower.We has identified the optimal number of turns and diameter of the primary coil through experiments and simulation.The optimized magnetic field is 3.6 times stronger than that of the conventional directly connected single-turn coil.After analyzing and simulating the discharge circuit of the pulsed intense magnetic field device,we test the different specifications of inductively coupled coils.It is found that for the discharge system of 2.4 ?F capacitance,the optimized parameters of the primary solenoid are 35 turns and 35 mm diameter.At the charging voltage of 20 kV,the peak magnetic field reaches 19 T in the magnetic field coil.At this time,the width of the flat-top magnetic field(the magnetic field intensity is more than 95%of the maximum value)of the magnetic field coil is about 3 ?s,and the rising edge of the waveform is about 5.4 ?s.In order to achieve stronger magnetic field on the inductively coupled coil,we test the characteristics of the magnetic field by different materials of inductively coupled coil with the discharge voltage of the device.Comparing with brass coils which was expanded and damaged under a discharge voltage of 30 kV,an inductively coupled coil made of beryllium copper with a stronger yield strength can work normally with a discharge voltage of 35 kV.And it can provide the magnetic field of 33 T.This creates conditions for our research with stronger magnetic field of laser plasma experiment.