Successive injection of opposite magnetic helicity: Evidence for active regions without coronal mass ejections

Magnetic helicity (MH) is a measure of twist and shear magnetic field. MH injected in the active region (AR) corona through photospheric footpoint motions causing twisted sheared fields. From conservation property helicity, it was conjectured that an already flux rope (FR) with continuous injection inevitably erupts to remove excess accumulated coronal helicity. Therefore, understanding nature evolution transfer crucial reveal intensity flare/CME activity. Using time-sequence vector-magnetograms \textit{Helioseismic Imager}, we study emerging AR 12257. The this inject positive first 2.5 days followed by negative later. This successive opposite consistent sign mean force-free parameter ($\alpha_{av}$), orientation magnetic-tongues. Also, extrapolated structure exhibits transformation global-shear without FR core AR. No CMEs are launched from but C-class flaring activity observed predominantly second half period. ARs reversal not favorable formation therefore important identify CME-less readily. A possible scenario these when one replaced sign, field different connectivity undergoes reconnection at scales giving rise both intermittent flares enhanced heating.