Design and Engineering Commissioning of High Frequency Pellet Injector for Experimental Advanced Superconducting Tokamak

Herein, we reported the design, construction and engineering commissioning of the high frequency pellet injector (PI-50), based on the ice-formation by screw extrusion and pneumatic accelerationtechniques and dedicated to Experimental Advanced Superconducting Tokamak (EAST): one of the world'sfull superconducting tokamaks resembling the plasma configuration of International Thermonuclear Experimental Reactor (ITER) . The novel pellet injector, mainly responsible for the mitigation in edge localized mode (ELM) and core fueling for EAST, comprises two identical injection modules, a gas supply and pumping/cryogenic units. The cylindrical pellets, 1. 2~. 8 mm long and 1. 5 mm in diameter, were injected at a frequency of 1 ~ 50 Hz and a velocity of 150 ~ 250 m/s.The newly-developed pellet injector was evaluated with the lab-built test platform and installed in the experimental site of EAST. The preliminary results show that the new injectorsatisfied the stringent design requirements. The trial operation was scheduled in the second half of 2017.