Study On Magnetic Field Intensity Affecting Spectrum Diagnosis In Hall Effect Thruster Channel

Hall effect thruster(HET)is widely used in aerospace field as an electric propulsion device, with the advantages of high efficiency, high specific impulse, long lifetime, etc. The spectrum diagnosis method is very suitable for diagnosing plasma parameters in the HET channel. But the magnetic field existing in the channel affects the spectroscopic diagnostic method . So in this paper, the main work are as followings:In the second chapter , we analys how the magnetic field affects the spectral lines intensity distribution in the HET channel. With the existence of the electromagnetic field in the HET channel, electrons conveys by making hall driftings . The stronger is the magnetic field , the smaller is the drifting radius , and the larger is the electron density. It will cause the increase of electronic atomic collision frequency, and the number of photons from transition will grow. In this case, the spectrum lines which couldn't be detected because of low energy can now be observed. Although the existence of the magnetic field will lead the atomic energy level to be split and the spectral lines to be split consequently, but it doesn't cause the spectrum line intensity to increase or new spectral lines to appear.In the third chapter ,we discuss the existence of the magnetic field how to broaden atomic spectrum lines. In the cathode discharge experiment, we find the phenomenon that the spectrum linewidth is broadened as the magnetic field strength increases and the magnitude of broadenings are consistent with the Zeeman theoretical value. At the same time, the existence of the grating can also cause the broadenings of spectrum lines. In order to eliminate the deviation caused by magnetic field and spectrometer itself, and to improve the precision of the spectrum diagnosis in the light intensity measurement, using the method of the integral near the center wavelength of specific spectrum line light intensity.In the fourth chapter , we discuss the phenomenon of krypton atomic energy level transition branching coefficient ratios changing in the HET channel. In the cathode discharge experiment, energy level transition we calculate the branching coefficient ratios as the magnetic field strength changes . We found that as the magnetic field strength increases, the 2P₄ level branching coefficient ratio increases along with 2P₆ level and 2P₆ level, the 2P₇ branch coefficient ratio decreases, the 2P₃ level and 2P₁₀ level branch coefficient ratios does not change basically. The conclusion is that the change of the magnetic field strength influences the branching coefficient ratios in different ways. So in the spectroscopic diagnostic method, the branching coefficient ratios should be chosen according to the practical situation.