  Aims. Solar active regions (ARs), which are formed by flux emergence, serve
as the primary sources of solar eruptions. However, the specific physical
mechanism that governs the emergence process and its relationship with flare
productivity remains to be thoroughly understood. Methods. We examined 136
emerging ARs, focusing on the evolution of their magnetic helicity and magnetic
energy during the emergence phase. Based on the relation between helicity
accumulation and magnetic flux evolution, we categorized the samples and
investigated their flare productivity. Results. The emerging ARs we studied can
be categorized into three types, Type-I, Type-II, and Type-III, and they
account for 52.2%, 25%, and 22.8% of the total number in our sample,
respectively. Type-I ARs exhibit a synchronous increase in both the magnetic
flux and magnetic helicity, while the magnetic helicity in Type-II ARs displays
a lag in increasing behind the magnetic flux. Type-III ARs show obvious
helicity injections of opposite signs. Significantly, 90% of the
flare-productive ARs (flare index > 6) were identified as Type-I ARs,
suggesting that this type of AR has a higher potential to become flare
productive. In contrast, Type-II and Type-III ARs exhibited a low and moderate
likelihood of becoming active, respectively. Our statistical analysis also
revealed that Type-I ARs accumulate more magnetic helicity and energy, far
beyond what is found in Type-II and Type-III ARs. Moreover, we observed that
flare-productive ARs consistently accumulate a significant amount of helicity
and energy during their emergence phase. Conclusions. These findings provide
valuable insight into the flux emergence phenomena, offering promising
possibilities for early-stage predictions of solar eruptions.
