Investigation On Characterization Of High-Intensity Pulsed Ion Beam And Its Ablation Effect On MEtallic Materials

High-intensity pulsed ion beam (HIPIB) technique, originated from inertial confinement fusion (ICF) project, has received extensive attention as a tool for research in materials surface engineering in recent years. The new requirements for applications in material surface engineering urge a new type of HIPIB apparatus, for instance, the generation of medium-power-density ion beam, high-stability ion beams and long-lifetime ion source etc. Therefore, characterization of high power ion diode-magnetically insulated ion diode (MID), the key issue for the technique development, is considered in this dissertation. The investigations of HIPIB generation and its mechanisms have been carried out in a TEMP-6 HIPIB apparatus, in order to optimize the configuration of ion diode and its ion beam parameters for materials surface treatments. Moreover, the ablation behavior of HIPIB-irradiated metallic materials has been studied systematically to clarify formation of the different ablated surface morphologies on the metallic materials, providing an experimental evidence for exploring the interaction mechanism between HIPIB and materials.Characterization of an external-magnetic field MID with polymer anode and a self-magnetic field MID with graphite anode operated in unipolar and bipolar pulse mode, respectively, has been performed. It is found that the characteristics of HIPIB are mainly depended on two crucial factors, i.e. the properties of insulated magnetic field and anode plasma. For the external-magnetic field MID, the cathode with improved structure works as a "close" magnetic coil that effectively increases the continuity and uniformity of magnetic field, and then ensures the stability of dense anode plasma formation. Under a certain magnetic field, the density and stability of anode plasma determines the ion current density and its fluctuation. The maximum output of ion beam current is obtained at a charging voltage of 8 kV for the magnetic field power system, which is in accordance with the theory of magnetic insulation. The ion beam parameters are an accelerating voltage of 300 kV, an ion current density of 300 A/cm2 with beam pulse width of 80 ns and with composition of 70% proton and 30% carbon ions. The fluctuation of ion beam has been controlled within 20%, significantly lower than that of 50-80% for external-magnetic field MID of annular configuration and ion diode without magnetic field by using polymer anodes. For the self-magnetic field MID with relatively simple structure, the stability of self-magnetic field generated by electron flow is obtained by adjusting the diode gap and the delay time of bipolar pulse. Under the combined effect of self-magnetic field and electrical field in the diode, stable and dense anode plasma was produced. At the delay time when the area on the anode surface bombarded by electrons expands to a maximum field, the upper limit of ion beam current output is reached. The ion beam parameters are an accelerating voltage of 220 kV, an ion current density of 350 A/cm2 with beam pulse width of 70 ns and with composition of 30% proton and 70% carbon ions. The fluctuation of ion beam has also been controlled at about 20%.The samples of pure Ti, Ti6A14V alloy and y-TiAl intermetallics have been irradiated by HIPIB with C/H ions of ion current density of 60-250 A/cm2 at 220 kV and shot number of 1-30. Two kinds of original pure Ti samples were selected with different surface roughness, i.e. high-roughness and low-roughness ones, respectively, whereas only low-roughness samples were for Ti6A14V alloy and r-TiAl intermetallics. It is found that the ablated surface morphologies for both the Ti samples of different roughness have a similar change trend from roughening to smoothing with increasing the shot number, where the surface roughening is relatively weaker at lower ion current density. Moreover, the surface roughening is obviously restrained on the low-roughness Ti samples. Therefore, the surface roughening and smoothing can be adjusted by controlling the HIPIB irradiation pa...