Ion Beam Energy Density Research Articles

Ablation Behavior of Titanium Irradiated by High-Intensity Pulsed Ion Beams

A complementary study on experimental observation and theoretical modeling has been performed to investigate the ablation behavior on titanium irradiated by high-intensity pulsed ion beams (HIPIB) with energy density of 70 J/cm2 up to 3 shots. The surface morphology with a typical waviness feature on the irradiated surface was observed by scanning electron microscopy (SEM). The observed surface morphology indicates a severer ablation in the center of irradiated area, leading to a fluctuation of liquid layer spreading radially to the peripheral area, due to the spatial distribution of ion beam energy density along the radial direction. The ablation process was simulated from the modeling of heat transfer in the irradiated samples using an axisymmetric model based on enthalpy formulation. The computational results are in good agreement with the experimental findings in the ablation mass with a trend of severer ablation in the center of irradiated area.

Application to Space Propulsion with Ablation Plasma Produced by Pulsed Ion Beam

In this paper, we showed the performance of a propulsion system in space by ablation plasma produced by pulsed ion beam and its controllability. First, the fundamental study of flyer acceleration with ablation plasma produced by irradiation of an intense pulse ion beam was explained numerically. Here, we used a one-dimensional hydrodynamic model based on the stopping power taking the interaction between the flyer material and ion beam into account. Using this numerical model, a maximum flyer velocity of about 8 km/s and ablation pressure of 20 GPa could be obtained at the ion beam energy density of 4 kJ/cm2 and the pulse width of an incident ion beam of 60 ns. Moreover, our numerical results agreed well with experimental ones. From these results, we could estimate performance of the space propulsion system with ablation plasma produced by pulsed ion beam which is an impulse bit of 2000 Ns/m2 and a specific impulse of about 5000-6000 seconds at the ion beam energy density of 4 kJ/cm2 and the pulse width of an incident ion beam of 60 ns. In addition, this paper also discussed the controllability of impulse bit, and specific impulse and we finally found that changing ion beam acceleration voltage, energy density, power density, and the duration of ion beam irradiation could control both performances. Furthermore, we found that the important factors are to control the acceleration voltage and pulse width in order to improve the space propulsion performance of this system.

Ion beam processing of magnesium oxide thin films for PDP application

In plasma display panels (PDPs), MgO (magnesium oxide) thin film is used as a protective layer that is placed between the electrodes on the front glass panel on one side of the discharge cells. The aim of this study is to improve the secondary electron emission coefficient of the protective layer. This improvement leads to reduction in consumption of energy. In this study, MgO thin films were prepared using electron beam evaporation method. The ion beam-assisted deposition (IBAD) technique is used to control the crystal orientation, surface nano-morphology, density, and composition. Oxygen ion beam was utilized to irradiate the growing films. In order to control the film properties, the acceleration energy and current density of ion beam and the deposition rate were taken as the variables. The crystallinity, density, composition of the films were analyzed by X-ray diffraction (XRD) and Rutherford backscattering spectroscopy (RBS). The secondary electron emission coefficients were measured by an apparatus developed in this study. The experimental results show that the irradiation of ion beam during deposition changes the crystal structure of the films and it influences their secondary electron emission coefficient.

The Intense Pulsed Ion Beam Treatment and the Titanium Nitride Coating of Hard Alloy for Cutting Tool

The aim of this work was to investigate adhesion increasing of titanium nitride coating deposited at hard alloy tool’s surface pretreated by intense pulsed ion beam of different energy density. Two alloys were treated by high-power pulsed ion beam of 1÷3.75 J/cm2 energy density. Analyzing the data obtained from tunnel microscopy, X-ray spectrum and measurements of surface relief geometry characteristics, such as roughness and profile length, we came to the following conclusion. First, the value of energy density of ion beam plays the key role in the formation of the relief and phase structure of the surface. Second, these two characteristics are almost independent of the initial characteristics of the irradiated alloys.Also, the article touches the results of scratch-test of the titanium nitride coating. The results demonstrate changes in wearing and destruction mode of the coating deposited at the tool treated by ion beam.

Ion irradiation of poly(methyl methacrylate) for precise control of electrical and optical properties

AbstractIon irradiation with Xe+ has been utilized to produce electrical conductivity in PMMA, as measured using a four‐point in‐line probe. Incident ion beam energy and current density have been varied to investigate their effect on electrical conductivity and optical absorbance of the samples after irradiation. Results support the premise that selection of beam parameters that maximize the ratio of energy transfer‐producing displacements to energy transfer‐producing ionization maximizes the ratio of induced conductivity to induced absorbance in the irradiated samples. Conductivity versus ion dose has also been shown to be well estimated using a damage trial model. © 1994 John Wiley & Sons, Inc.

Preparation of Aluminum Nitride Epitaxial Films by Electron Cyclotron Resonance Dual-Ion-Beam Sputtering

Aluminum nitride (AlN) thin films have been deposited on (11̄·2) sapphire by an electron cyclotron resonance (ECR) dual-ion-beam sputtering method. We have thoroughly investigated the dependence of the crystallinity and surface smoothness of the AlN thin film on the assisted conditions and sputtering conditions. The AlN thin film deposited under assisted conditions with the nitrogen ion beam energy and current density of 100 eV and 0.32 mA/cm2, respectively, and sputtering conditions with the arrival aluminum flux rate to the substrate surface (Al flux rate) and argon (Ar) ion beam energy of 42 Å/min and 800 eV, respectively, is a single-crystal film with a very smooth surface. In order to prepare the epitaxial film, the Ar ion beam energy must be increased according to increases in the Al flux rate, and decreased according to decreases in the Al flux rate.