Consumable embedded microwave Antenna in AP/HTPB propellant to focus energy at the reaction front

This study demonstrates a novel method to modulate the burn rate of AP/HTPB propellants by embedding a consumable microwave (MW) antenna, which can be directly coupled to a MW source. The tip of the antenna, which is being consumed, is thus always at the burning surface of the propellant and radiates MW energy to weakly absorbing HTPB. We found a significant increase in burn rate (up to ∼2X), with increasing MW power, despite the fact that the flame temperatures were unaffected. These results indicated that the function of the antenna was restricted to delivering power to the condensed phase. Electric field simulation indicates that the MW energy focused at the burning surface and along the axial direction along the MW antenna. This study shows that focusing on MW energy on the burning surface can be used to modulate burn rate of propellants by embedding a consumable MW antenna.