MRT unstable plumes are observed in a loop-like eruptive prominence using SDO/AIA observations .
The small-scale cavities are developed within the prominence , where perturbations trigger dark plumes ( P1 & P2 ) propagating with the speed of 35-46 km s ^ { -1 } .
The self-similar plume formation shows initially the growth of linear MRT unstable plume ( P1 ) , and thereafter the evolution of non-linear single mode MRT unstable second plume ( P2 ) .
The Differential Emission Measure ( DEM ) analysis shows that plumes are less denser and hotter than the prominence .
We have estimated the observational growth rate for both plumes as 1.32 \pm 0.29 \times 10 ^ { -3 } s ^ { -1 } and 1.48 \pm 0.29 \times 10 ^ { -3 } s ^ { -1 } respectively , which are comparable to the estimated theoretical growth rate ( 1.95 \times 10 ^ { -3 } s ^ { -1 } ) .
The nonlinear phase of an MRT unstable plume ( P2 ) may collapse via Kelvin-Helmholtz vortex formation in the downfalling plasma .
Later , a plasma thread has been evident into the rising segment of this prominence .
It may be associated with the tangled field and Rayleigh-Taylor instability .
The tangled field initiates shearing at the prominence-cavity boundary .
Due to this shear motion , the plasma downfall is occurred at the right part of the prominence-cavity boundary .
It triggers the characteristic KH unstable vortices and MRT unstable plasma bubbles propagating at different speeds and merging with each other .
The shear motion and lateral plasma downfall may initiate hybrid KH-RT instability there .