An Indirect Iterative Method to Couple the Generator to the MHD Load for Future Z-Pinch

Abstract

For the future Z-pinch accelerator, the radiation magnetohydrodynamics (MHD) simulation of the load is urgently needed to investigate its performance. Also, more accurate results can be obtained if a detailed generator model is coupled to the MHD model. However, because of the non-TEM modes in the monolithic radial transmission lines (MRTLs), the field-circuit coupling model for the generator is too complex to be coupled to the MHD model directly. Therefore, an indirect iterative method is proposed. In this method, the load is simplified to a resistor and an inductor connected in series. The iterative loop $n$ is: using the load current $I_{\text {load},n- 1}$ ( $t$ ) calculated in the previous loop, the MHD model calculates the load resistance $R_{\text {load},n}$ ( $t$ ) and load inductance $L_{\text {load}, n}$ ( $t$ ) in a complete calculation time and using the load parameters $R_{\text {load},n}$ ( $t$ ) and $L_{\text {load},n}$ ( $t$ ), the field-circuit coupling model calculates the load current $I_{\text {load},n}$ ( $t$ ) in a complete calculation time. The initial load current $I_{\text {load},n} = 0$ ( $t$ ) is obtained from the field-circuit coupling model connecting the 0-D model for the load. The loop continues until the load current converges. Using a simple drive source, the reliability of this method is proved and then it is used for the simulation of Z800 accelerator, a future Z-pinch accelerator, with wire array. After three iteration loops, the final parameters, such as the load current and radiation power are obtained. The indirect iterative method is useful for evaluating the load performance in a coupled load generator system without the need for a lot of code development on the already established MHD model.