Experimental Study Of Supersonic Molecular Beam Injection In The Hl-2a Device

High-temperature plasma diagnosis is an important topic of the study of the thermonuclear fusion. The author of this paper has taken part in the physical experiments on the HL-2A tokamak in Southwest Institute of Physics, and has carried on some experiments about both spectroscopic diagnostics and supersonic molecular beam injection in the spectroscopy group and the group of molecular beam. The experiments in this article are also related to the above two aspects: one is the use of spectral analysis method for measuring the density distributions of the neutral hydrogen and deuterium, the other is about the analysis of the characteristics of the supersonic molecular beam injection and the improvements of the experimental equipments.Spectroscopic diagnostics is an effective way of plasma diagnosis, by which we can obtain some important parameters of the plasma through the analysis of plasma radiations. This article introduces the basic situations of the plasma radiation, and the principles of spectrum diagnosis are briefly summarized here. At the same time, the related spectral diagnostic equipments on the HL-2A tokamak are also mentioned in this paper. In this experiment, we collected the radiations of the neutral hydrogen and deuterium through the Hαarray on the HL-2A tokamak device, and then through the inverse Abel transform, we can draw the plasma density distribution which is used as an important parameter for the analysis of fusion plasma.The experiments of this time focus on the supersonic molecular beam injection. Supersonic molecular beam injection is not only an effective way of plasma refueling, but also an important auxiliary method for other physical experiments. This article describes in detail the formation of supersonic molecular beam and the experimental apparatus of the injection system. The study of the supersonic molecular beam injection includes the injection effect, injection speed, injection depth and so on. With the help of the diagnostic systems on HL-2A tokamak, we can see clearly the changes of the plasma density caused by the injection of the beam. Using CCD camera, we can obtain the actual image of molecular beam, and we can observe the interactions between the injected gas and fusion plasma. The injection speed of molecular beam can be easily estimated by the flying-time method, and the depth of injection can be figured out by observing the spread of the plasma density disturbance. The results of the experiments have proved that supersonic molecular beam injection can bear the mission of refueling on HL-2A device, and has an enormous development potential.