In this article, non-thermal plasma technology at atmospheric pressure for fine powder processing was investigated. A common potato starch was modified within Argon plasma to produce a commercial well-known modified starch known as HT drilling starch. A theoretical model was developed for possible future scale-up of the designed suitable plasma reactor in the emerging field of plasma modification of starch. The model predicts the incipient condition for full fluidization of the solid particles within the plasma fluid. This condition led to maximum interaction between the plasma species and the starch granules. The predicted incipient full fluidization velocity in the model was in consistent with required experimental flow conditions for producing the desired modified starch. Since the plasma modified starch was used as an adhesion additive, the known characteristics in the oil & gas-well drilling fluid such as Fluid-Loss (F.L) and viscosity were reduced more than 30% and 10%, respectively.