Laser Induced Fluorescence Diagnostic And Planar Laser Induced Fluorescence Imaging

Laser induced fluorescence(LIF)diagnostic technology,as a non-intrusive,highly selective and sensitive active spectrum diagnostic method,has been widely used in various types of plasma devices.Different from the filament source and RF source,the linear magnetization plasma device(LMP)uses an oxide coated cathode plasma source which has a strong electron emission capability and generates a stable and uniform,high density and ionization rate plasma.It is an ideal experimental environment for magnetic field reconnection and other plasma physics study.The LIF diagnostic system can measure plasma density,ion temperature and other parameters on the LMP device.In the oxide coated cathode discharge mode,relevant physics studies can be performed With the basic probe and LIF diagnostic.In this paper,a set of pulsed dye laser system meets the requirements of LIF diagnostic with narrowband laser pumping and PLIF imaging with broadband laser pumping at the same time.A self-made FPI is used to achieve the laser linewidth compression and wavelength sacanning in this LIF diagnostic and PLIF imaging system on the LMP device.The pulsed dye laser has high energy and good time resolution,so the fluorescence intensity is so strong that the fluorescence signal can be directly collected after the amplification without the weak signal detection tools.This system will make great convenience for the experiment study.First of all,the author analyzed the research results of LIF diagnostic through sufficient investigation work and discussed the influence of multiple broadening mechanisms on the absorption spectrum in LIF diagnostic.Thereafter,an iodine absorption spectrum measurement system was established and realized synchronous online calibration of pumping laser wavelength in the LIF diagnostic process.The LIF diagnostic system was completely built on the LMP device.Secondly,a multi-dimensional LIF diagnostic was performed in the oxide coated cathode Ar plasma,and the ion velocity distribution function was measured to obtain an ion temperature of 0.2 eV,which is in agreement with the theoretical estimation and the previous experimental results.According to the observed drift of the ions' velocity distribution,the macroscopic velocity of the ions and the polar rotation speed could be measured.Finally,by studying the dependence of background fluorescence intensity on the external control parameters such as neutral pressure,discharge voltage,and axial magnetic field,it was found that the source of metastable ions is different at different stages of the continuous discharge process,which is different from the previous results.The deeper understanding of the process of oxide cathode discharge is conducive to the optimal adjustment of the fluorescence intensity in the LIF diagnostic.At the same time,it is well prepared for the PLIF imaging.