A Supersonic Molecular Beam Injection System on the J-TEXT Tokamak

A supersonic molecular beam injection (SMBI) system has been developed as a new fueling method for the J-TEXT tokamak. According to experimental needs, the system can provide various supersonic gas jets with the pressure range 0.2–2.0 MPa and pulse duration 0.2–10 ms. In this paper, the structure of the system is described in detail, including injectors, controller and gas line. Wave forms of the controller output show a fast response of the system. The evolution of pressure curve in the vacuum chamber indicates the system works well. Test results also show that the particle number of SMBI is linear proportional to the product of gas pressure and pulse duration. For different pressure of 0.5, 1.0 and 1.66 MPa, the beam velocities are estimated about 0.9, 1.2 and 1.4 km/s, respectively. Besides, fuelling experiments with the SMBI system are performed. Significant density increase demonstrates the fuelling abilities of both LSMBI and HSMBI.