34 / 2023-04-04 09:43:04

Simulation of Large Scale FRC Formation, Translation, Mering and Magnetic Compression on MT Device

FRC,MHD

In recent years, the research on large-scale merging FRC target has been proved to be beneficial to improve the target quality. Huazhong University of Science and Technology proposed to use magnetic field compression merging FRC target to reach ignition condition. This includes three processes: formation, merging and magnetic compression. Magnetic compression is the key to realize ignition, and the action process of magnetic compression can be well analyzed by simulation. By analyzing the operation process and parameter characteristics of MT device, IFP developed a two-dimensional MHD code named MTP and realized the full process simulation of Magnetic Trap device. The simulation of dynamic formation, merging and compression of Magnetic Trap plasma gives the influence of key parameters, which deepens the understanding of physical process. MTP realizes the effective combination of physical experiment and simulation, which effectively proves that the experimental device realizes the merging process of two FRC target, and assists in the deep interpretation of experimental data.

As shown in the following figure, The full process of formation-ejection-collision-merging of Magnetic Trap device is simulated. The merging target density is 5×10¹⁵ cm^-3, the electron temperature is 100 eV, and ion temperature is 150 eV, the radius and axial length of target is 20cm and 100cm respectively. the life of the merging target is about 70 μs. The ejection velocity is about 160km/s and the collision is about 20 μs. In the evolutionary simulation research, with the Magnetic Trap device design parameters, the radius of the magnetic compression target is about 10cm, the electron and ion temperature reaches 600eV and 250eV respectively.Density of compression target reaches 6×10¹⁵ cm^-3. It is also found that the tearing instability develops more seriously with the increase of compression field.

Using the data from magnetic probe array of Magnetic Trap device, the separatrix of plasma target can be inverted in the transmission region and merging region. It can be seen that at about 100 μs on the left side, two yellow lines can be seen entering from both ends of the axial direction and intersecting at the midpoint. The darkest red color at the intersecting point means that the radius is the largest at this time, and this position then undergoes a short radius reduction (relative to the adjacent position in the axial direction and also relative to the front and back in time) and then recovers. The results are basically consistent with the merging process of Magnetic Trap collision obtained by MTP simulation. The separatrix position extracted from the simulation results is obtained by using the same processing method. As shown in the following figure, it can be seen that compared with the experimental results, the interference signs are less, and it can be more clearly distinguished that two FRC targets merging process.