This invention relates to enhancing a gas-phase reaction in a plasma comprising: creating plasma by at least one plasma source, and wherein that the method further comprises: generating ultrasonic high intensity and high power acoustic waves having a predetermined amount of acoustic energy by at least one ultrasonic high intensity and high power gas-jet acoustic wave generator, where said ultrasonic high intensity and high power acoustic waves are directed to propagate towards said plasma so that at least a part of said predetermined amount of acoustic energy is absorbed into said plasma, and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves is at least substantially 100 W.