For exploiting advantages of electron beam air plasma in some unusual applications,a Monte Carlo(MC) model coupled with heat transfer model is established to simulate the characteristics of electron beam air plasma by considering the self-heating effect.Based on the model,the electron beam induced temperature field and the related plasma properties are investigated.The results indicate that a nonuniform temperature field is formed in the electron beam plasma region and the average temperature is of the order of 600 K.Moreover,much larger volume pear-shaped electron beam plasma is produced in hot state rather than in cold state.The beam ranges can,with beam energies of 75 keV and 80 keV,exceed 1.0 m and 1.2 m in air at pressure of 100 torr,respectively.Finally,a well verified formula is obtained for calculating the range of high energy electron beam in atmosphere.
Large size of air plasma at near atmospheric pressure has specific e?ects in aerospace applications. In this paper, a two dimensional multi-fluid model coupled with Monte Carlo(MC) model is established, and some experiments were carried out to investigate the characteristics of electron beam air plasma at pressure of 100-170 Torr. Based on the model, the properties of electron beam air plasma are acquired. The electron density is of the order of 1016m-3and the longitudinal size can exceed 1.2 m. The profiles of charged particles demonstrate that the oxygen molecule is very important for air plasma and its elementary processes play a key role in plasma equilibrium processes. The potential is almost negative and a very low potential belt is observed at the edge of plasma acting as a protection shell. A series of experiments were carried out in a low pressure vacuum facility and the beam plasma densities were diagnosed. The experimental results demonstrate that electron density increased with the electron beam energy, and the relatively low pressure was favorable for gaining high density plasma. Hence in order to achieve high density and large size plasma, it requires the researchers to choose proper discharge parameters.
In this paper,surface modification of the strut dowel used in ITER PF support is reported.Different ions (nitrogen/titanium) with different doses are implanted into the surface of strut dowel.The result of Auger Electron Spectroscopy (AES) indicates that nitrogen can be implanted more deeply than titanium under the implantation condition of 60kV accelerating voltage and a dose of 8×10 17/cm2 nitrogen.Surface Micro Hardness (SMH) and wear resistance are improved remarkably.Further SEM observation shows that there are no obvious scratches and damages after wear test.
