Abstract:
The report will present the results of constructing a mathematical model of plasma transport in a spiral magnetic open trap SMOLA created at the Budker Institute of Nuclear Physics SB RAS. The mathematical model is based on the use of a helical magnetic field configuration to hold plasma in the device. Plasma confinement is carried out due to the braking force that occurs when the plasma rotates in crossed electric and helical magnetic fields. In this system, the plasma is held in the central part, which works like a classical gas dynamic trap. The role of the proposed sections with a spiral magnetic field is to reduce particle losses along the magnetic field and, consequently, to reduce energy losses. The mathematical model of the transfer of matter in a helical magnetic field is based on a system of equations of magnetic hydrodynamics in a cylindrical coordinate system, taking into account symmetry. The stationary case is considered due to the course of experiments in which, after a short installation stage of 120 ms, the plasma in the main part of the installation retains its spatial configuration unchanged. The screw confinement effect was obtained in field experiments and confirmed by calculations. The stationary equation of matter transfer contains the second derivatives in space. The optimal template for the approximation of the mixed derivative based on the test problem has been selected. A comparison of the numerical implementation of the model by the establishment method and the Seidel method is carried out. In order to move to a more accurate qualitative and quantitative coincidence of the data of calculations and experiments, it is necessary to determine the functional dependencies for the coefficients of the model. Namely: the coefficient of diffusion in the transverse field, temperature, the proportion of trapped particles, the ratio of the length of the system to the free path of the ion. As a result of using a large number of experimental measurements of plasma density in several trap sections, it is proposed to validate the model. The determination of functional dependencies will allow controlling the process of suppressing longitudinal losses of particles and energy from open traps with reactor-class plasma. All parameters used correspond to the data of the SMOLA device. The developed software package will be in demand for predicting the results of the designed devices with a magnetic field of a screw configuration.
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