An atmospheric pressure glow discharge in air stabilized by a magnetic field and its application on nitrogen fixation

Abstract An atmospheric pressure glow discharge in air stabilized by a magnetic field is reported. The plasma is fixed at a position when the direction of the Lorentz force and the direction of the air flow is opposite. Under such condition, a stable glow discharge can be achieved and the plasma parameters can be independently controlled by the applied voltage, the magnetic field and the air flow rate, which is not the case for the widely used gliding arc (GA) discharge. For applied voltage of 6.5 kV, air flow rate of 2 L min −1 , and magnetic field of 0.11 T perpendicular to the paper pointing outward, the discharge voltage ( V dis ) and discharge current ( I dis ) are 1.2 kV and 49.7 mA, respectively. The rotational and vibrational temperature is about 3420 K and 4550 K, respectively. The electron density is on the order of 10 14 cm −3 and the reduced electric field of plasma is about 36.9 Td, which is favorable for vibrational excitation of N 2 to promote the production of NO x . As the plasma is fixed at a position, all the gas has to pass the plasma region and treated by the plasma when they are flowing, which is not the case for GA discharge where only a little percentage of gas is actually treated by the plasma. The energy cost of NO x production for the plasma stabilized by magnetic field of 0.19 T pointing outward is about 2.65 MJ mol −1 , which is 41% lower than the GA discharge.