Strong Energy Conversion by a Magnetic Hole Behind a Dipolarization Front

Dipolarization fronts (DFs) have been widely reported in the Earth's magnetotail and are suggested to play an important role in energy conversion. Magnetic holes (MHs) are also usually observed near DFs, and recent spacecraft observations suggest that they can be excited by interchange instability (ICI). However, whether the MHs near DFs could contribute to energy conversion is still unknown. Here, by using the Magnetospheric Multiscale mission observations, we find a sub-ion scale MH behind a DF. We present a two-dimensional illustration of the MH, revealing that such an MH was generated by the ICI. Inside this MH, a significant energy conversion up to ∼2 nW/m³ (higher than typical observations near DFs) is caused by the local electron vortex current inside the MH and the background electric field on the DF. This study improves our understanding of energy injection during substorms and energy conversion near DFs.