Research on the confinement of high-energy alpha particles in a perturbed magnetic dipole field

[Background] In a levitated magnetic dipole confinement device, the magnetic field excited by the Tilt-Slide-Rotate (TSR) or the Resonant Line Field (RLF) can disrupt the topology of the background magnetic field, thereby affecting particle confinement. [Purpose] This study aims to investigate the effect of magnetic disturbances generated by TSR coils and RLF effects on the confinement of alpha particles in a background magnetic dipole field. This research is of great significance for the heating of background plasma by high-energy alpha particles generated by DD-3He catalyzed nuclear reactions. [Methods] Firstly, this study establishes a collision loss model based on the parameters of the CAT-1 device. Secondly, an interchange mode stable background magnetic field is obtained by the DEGS (Dipole Equilibrium Grad-Shafranov Solver). Thirdly, the magnetic field disturbance is generated by the TSR coil and calculated using a line segment approximation method. And the poloidal magnetic field disturbance generated by the RLF effect is generated by adding a toroidal magnetic field with the same direction or two opposite directions in the background magnetic dipole field. Finally, the orbits of alpha particles in a magnetic field are simulated using the particle testing method. [Results] Due to the magnetic field generated by the TSR coil disrupting the structure of the closed magnetic field lines of the background dipole field, alpha particles injected close to the TSR coil side experience rapid loss. Additionally, this study simulates the magnetic field with a low poloidal mode number by superimposing a toroidal magnetic field on the background magnetic dipole field. The n = 0 poloidal disturbance magnetic field maintains a higher confinement particle fraction than the n = 1 magnetic disturbance within 10 microseconds, and after the flight time of alpha particles exceeds 10 microseconds, the confined particle fraction in the n = 0 mode rapidly decreases. [Conclusions] The magnetic field disturbances can cause rapid loss of alpha particles along an open magnetic field line, reducing the loss during high-energy alpha particle relaxation by controlling the operating current of the TSR coil and the RLF effect.