Abstract
<title>Abstract</title> <p>This paper presents a numerical investigation of self-field effects in a REBCO high-temperature superconducting double-pancake coil for the China Astro-Torus-1 (CAT-1) levitated dipole field experiment. Stable and reliable operation of the central magnet is essential for forming the required dipole-field configuration. Before modeling the complete operating condition, the intrinsic current redistribution caused by the coil self-field must be clarified. To address this issue, a two-dimensional axisymmetric homogenized finite-element model based on the H-formulation is developed. The anisotropic magnetic-field dependence of the critical current density is included. The external levitated-dipole background field is not considered, so that the effects of coil geometry, excitation waveform, and charging sequence can be examined independently. The current penetration rate is introduced to quantify screening-current penetration and redistribution. The results show that turn-to-turn spacing is the dominant geometric factor affecting current penetration. Pancake-to-pancake spacing has a weaker but still evident influence. The effects of inner radius and turn number are relatively small within the studied parameter range. A monotonic charging waveform without current overshoot helps suppress irreversible current redistribution. Same-direction simultaneous charging produces the lowest current penetration rate under the present self-field condition, owing to partial cancellation of screening currents between adjacent pancakes. This work provides a self-field benchmark for CAT-1 double-pancake coil-module design. It also offers physical guidance for future coupled studies involving external background fields, thermal effects, mechanical constraints, and practical power-supply conditions.</p>