From Soylent News:
Researchers have improved the design of Cylindrical shaped Hall thrusters (CHTs), a type of ion drive used in spacecraft:
More likely to be deployed than EmDrive.Researchers from the Harbin Institute of Technology in China have created a new inlet design for Cylindrical shaped Hall thrusters (CHTs) that may significantly increase the thrust and allows spaceships to travel greater distances.
[...] The researchers injected the propellant into the cylindrical chamber of the thruster by a number of nozzles that usually point straight in, toward the center of the cylinder. The angle of the inlet nozzles changed slightly, sending the propellant into a rapid circular motion and creating a vortex in the channel.
They then simulated the motion of the plasma in the channel for both nozzle angles using modeling and analysis software called COMSOL that uses a finite element approach to modeling molecular flow.
This resulted in a gas density near the periphery of the channel is higher when the nozzles are tilted and the thruster is run in vortex mode.
According to the study, the vortex inlet increases the propellant utilization of the thruster by 3.12 percent to 8.81 percent, thrust by 1.1 percent to 53.5 percent, specific impulse by 1.1 percent to 53.5 percent, thrust-to-power ratio by 10 percent to 63 percent and anode efficiency by 1.6 percent to 7.3 percent, greatly improving the thruster performance.
Effect of vortex inlet mode on low-power cylindrical Hall thruster (open, DOI: 10.1063/1.4986007) (DX)