Energy Extraction via Magnetic Reconnection in Kerr-Sen-AdS₄ Black Hole: Circular Plasma and Plunging Plasma

In this paper, we investigate the power and efficiency of energy extraction through magnetic reconnection in the Kerr-Sen-AdS₄ black hole, with a primary focus on both the circular orbit and plunging region. We plot the allowed regions for energy extraction and present corresponding power and efficiency values, comparing them with those of the Blandford-Znajek (BZ) mechanism. Our analysis reveals that energy extraction remains feasible even at a spin parameter as low as 0.5, significantly below previously reported thresholds, and the extracted power can exceed that of the BZ process under certain conditions. Furthermore, the dilatonic scalar charge b and the AdS radius l collectively contribute to lowering the spin threshold for energy extraction. The energy extraction process in the plunging region was further examined by analyzing the permissible energy extraction region, as well as the corresponding power output and efficiency. One can find that the energy extraction is possible even at a spin as low as 0.25. Crucially, parameter b actively lowers the energy extraction spin threshold, while parameter l exerts a counteracting effect, impeding such reduction. This trend shows a marked contrast with circular orbit behavior. Additionally, both power and efficiency in the plunging region consistently surpass those in the circular orbit region, indicating superior energy extraction capability in plunging region.