Magnetic field configuration of attitude control coil based on line segment approximation method

Abstract

BackgroundWhen the suspended dipole field coils experience significant disturbances during the operation of the suspended dipole field device, the Tilt-Slide-Rotate (TSR) coils are used to control the attitude of the dipole field coils, thereby preventing them from losing control.PurposeThis study aims at attitude control of dipole fields by coil forces of the TSR coils with relatively complex geometric structures.MethodsBased on the line segment approximation method, the modeling and analysis were conducted for scenarios where the dipole field coils return to their balanced position under conditions of dipole field tilt and offset by controlling the magnetic forces generated by the TSR coils on both opposite and same sides. The coupling magnetic field between the TSR coils and the dipole field coils was calculated, and the magnetic field line structure was analyzed. The excitation magnetic field of the TSR coils, in the form of sinusoidal currents, was simulated to induce azimuthal magnetic disturbances. Analysis was performed on the magnetic field line structure and phase of the perturbation magnetic field on the Poincaré section at the equatorial plane. [Results and Conclusions] If only one group of TSR coils on the same or opposite sides is used to control the dipole field coils to restore equilibrium, exhibited mechanical instability needs necessitating coordinated control by multiple sets of TSR coils. Applying pseudo-sinusoidal currents to all TSR coils induces compression and stretching effects on the background dipole magnetic field. By controlling the current of the TSR coils to control the phase of the compression position, the feasibility of controlling the attitude of the dipole field coils with multiple TSR coils has been validated. However, this process may also cause drift in the background magnetic field and the formation of open magnetic field lines, which could drive plasma instabilities and lead to particle loss.

Keywords

• line segment approximation method
• arbitrary curve loop current
• equilibrium analysis
• china astro-torus no.1