Development and implementation of Supersonic Molecular Beam Injection for EAST tokamak

As a method for plasma density control, Edge Localized Mode (ELM) mitigation and refueling, a Supersonic Molecular Beam Injection (SMBI) system is successfully developed and implemented for the Experimental Advanced Superconducting Tokamak (EAST). The SMBI is designed to produce a 400-1200 m/s molecular beam of hydrogen/deuterium for injecting into the plasma. An innovative system for measuring the injected particle number is also developed to increase the measuring accuracy of SMBI. In addition, a movable structure of the nozzle is designed to adjust the distance between the nozzle and plasma, in order to improve the fueling efficiency of SMBI by decreasing this separation distance. The successful implementation of SMBI provides an important tool for studying plasma density feedback control and ELM mitigation on the EAST campaign. To the best of our knowledge, the engineering design process of the SMBI system on the EAST has not been reported previously; therefore, the structure, implementation details, and the test results of the SMBI system are presented herein for the first time.