Investigation of boron powder flow rates on real-time wall

•The solid boron injection showed well ability on the control of carbon impurity and deuterium recycling on the basis of pre-discharges boronization in EAST.•There was a minimum flow rate, which is between 1.0 mg/s to 2.0 mg/s, for solid boron actively improving the wall conditions in specific plasma operation scenario.•There was a maximum solid boron flow rate, which is between 3.5 mg/s to 8.0 mg/s, for improving the wall conditions. When the boron flow rates exceed this maximum value, the plasma line averaged density would be influenced by boron induced fueling effects. The limit of boron flow rates for real-time conditioning of the first walls has been systematically investigated in the Experimental Advanced Superconducting Tokamak (EAST) with a full metal wall. Initially, solid boron injection demonstrated effective control over carbon impurities and deuterium recycling on the basis of pre-discharge boronization. A minimum flow rate, identified between 1.0 mg/s and 2.0 mg/s, was necessary for actively improving wall conditions under specific plasma operating scenarios, with this effect progressively enhancing as boron flow rates increased. Additionally, a maximum flow rate, estimated between 3.5 mg/s and 8.0 mg/s, was identified for these plasma conditions. When boron flow rates exceeded this maximum, boron-induced fueling effects influenced the plasma line-averaged density, and at excessively high flow rates, plasma disruption was observed.