Supersonic molecular beam injection (SMBI) is a widely used auxiliary fueling method in magnetic confinement devices, significantly influencing plasma flows and turbulence.

This study aims to investigate the effects of SMBI on flows and turbulence in the edge plasma of a tokamak.

The experiment was conducted on the J-TEXT tokamak with a major radius of 1.05 m and a minor radius of 0.255 m. The SMBI was injected into the vacuum through one of the bottom ports. A three-step Langmuir probe array was mounted on the top of the tokamak and was employed to measure and analyze edge plasma flows and turbulence with SMBI injection. Particular attention was given to geodesic acoustic mode (GAM) zonal flows, ion-ion collision frequency, turbulent Reynolds works, gradients, and turbulence-driven particle flux.

Results indicate that the GAM, turbulence, and turbulent particle flux are suppressed after SMBI for 40%~60%, 50%~70%, and 60%~70%, respectively, accompanying the increase in ion-ion collision frequency, and the decrease in turbulent Reynolds stress and the turbulent Reynolds work.

The suppression of GAM is related to the decrease in the nonlinear driving from turbulence and the increase in collision frequency; the decrease in turbulence may be the result of the flattening of density and temperature gradients; and the reduction of turbulent heat flux may come from the drop in the fluctuations of radial velocities.