Sci. Adv. 4, eaau5239 (2018)

Flights travelling supersonically experience large drag caused by shock waves, leading to a considerable increase in fuel consumption. Mounting a spike in front of the blunt body can mitigate this effect, but its aspect ratio is often limited by structural constraints, such as vibrations and mechanical stress. Now Paul-Quentin Elias and co-workers have shown an alternative solution, replacing the rigid spike with plasma filaments formed by ultrashort laser pulses.

The role of this immaterial spike was demonstrated by a test model placed in a Mach 3 supersonic wind tunnel. Intense femtosecond infrared laser pulses emerged from the front, leading to a sudden creation of a short-lived plasma column and leaving behind a long-lived hot and thin neutral air channel of reduced density. A transient reduction of more than 50% of the drag induced by the laser pulse was observed. Further adjusting the direction of the laser resulted in a net asymmetric drag, which may offer a means of control.