Intense Pulsed Ion Beam Irradiation Research Articles

Solid-State Dewetting of Thin Silver Films into Spherical Nanoparticles under High-Current Pulsed Ion Beam Irradiation.

Noble metal nanoparticles (NPs) are important in many applications, including light trapping of photovoltaic cells, photoelectrochemical applications, etc. The present study reports the formation of silver NPs from the as-deposited silver coatings on fused silica substrates by solid-state dewetting induced by high-current intense pulsed ion beam (IPIB) irradiation. We described the effects of IPIB irradiation with different ion beam current densities and numbers of pulses on NP morphology and compared the results with conventional rapid thermal annealing (RTA). IPIB irradiation enables superfast heating (higher than 109 K/s) and cooling, providing a superfast annealing solid-state dewetting mechanism. Our results demonstrate that the sphericity of silver NPs is enhanced after IPIB irradiation relative to RTA-annealed silver NPs. Our results suggest further possibilities of shape and sphericity control of silver NPs with very fast heating/cooling annealing rates.

Surface microstructure and phase structure of zirconia ceramics under intense pulsed ion beam irradiation

The surface microstructure and phase structure of zirconia (ZrO2) ceramics under intense pulsed ion beam (IPIB) irradiation were investigated in this work. Experiments were carried out on TEMP-4M accelerator with peak accelerating voltage, current density, and pulse duration of 220 kV, 150 A/cm2, and 80 ns. Micro-cracks with a height of up to 150 nm above the surface were observed and were deduced to be formed by the tensile stress during the shrinking process. The cross-sectional observation indicates that columnar structure thin layer with thickness about 1.23 μm was produced after IPIB irradiation. The GIXRD pattern indicates that obvious preferred orientation in (110) and (200) of t-ZrO2 was occurred in near-surface region after IPIB irradiation. Opposite micro-stress in bulk and near-surface region was revealed by W-H plot after Rietveld refinement. The evolution of mass loss and surface roughness of samples with pulse number was also investigated.

A method of real-time monitoring beam output stability of intense pulsed ion beam

Intense pulsed ion beam (IPIB) technology has made remarkable progress in surface modification, mixing, polishing, film deposition, and nano powder synthesis in recent years. However, the surface properties of materials under IPIB irradiation are highly sensitive to beam intensity variations. Deviations from acceptable parameter range can change the surface characteristics and increase prevalence of defects. Consequently, the real-time online monitoring of beam stability during irradiation experiments and promptly identifying of pulses exhibiting significant parameter jitter are of significance in accurately analyzing results and optimizing surface modification. This study presents a fast-response pulse X-ray diagnostic system by employing EJ-200 plastic scintillator, 9266FLB photomultiplier tube, and Tektronic TDS 2024 four-channel oscilloscope. Single particle test demonstrates that the system achieves a time resolution of 6 ns, meeting the requirements for temporal response to detecting pulse X-ray signals with a half-width of ~80 ns. By adjusting the insulation magnetic field strength of the ion diode, the IPIB output level is regulated. The diagnostic system successfully captures X-rays emitted by the external magnetic insulated ion diode operating at different output levels. Simultaneously, the ion beam energy density is measured by using an infrared camera. To mitigate diagnostic errors stemming from target ablation, the maximum energy density is controlled to be below 1.32 J/cm<sup>2</sup>. Analysis results establish a positive correlation between X-ray intensity and ion beam energy density. This relationship arises from the influence of the insulating magnetic field adjustment on the diode's operating voltage, which subsequently affects the bremsstrahlung radiant intensity and ion beam emission intensity. This correlation offers the potential for the real-time monitoring of IPIB beam output stability by utilizing X-ray signals. To further corroborate the synchronized changes in pulse X-ray intensity and ion beam intensity, Faraday cup is employed as an alternative to infrared imaging method for measuring ion current density. Results demonstrate that the amplitude of the X-ray signal changes synchronously with fluctuations of ion current density. It is worth noting that when the output intensity of ion beam deviates significantly (more than 10% of the preset value), the diagnostic system will respond quickly. These findings validate the efficacy of the proposed non-interceptive diagnostic method of real-time monitoring the intense pulsed ion beam output stability.

Study of phase transformation and surface microstructure of alumina ceramic under irradiation of intense pulsed ion beam

Intense pulsed ion beam (IPIB), featured with pulsed high-power density, has been widely used in the modification of structural material, especially in high strength materials. The effects of IPIB treatment on phase transformation and surface microstructure of alumina ceramics were investigated in this work. Experiments were carried out on the BIPPAB-450 accelerator with peak accelerating voltage and current density of 360 kV and 170 A/cm2. X-ray diffraction (XRD), scanning electron microscope (SEM) and atomic force microscope (AFM) were used to analyze the phase transformation and cross-section and surface morphology of alumina ceramics under IPIB treatment. The XRD pattern indicated that phase transformation from α-Al2O3 to γ-Al2O3 occurred on the irradiated area due to the combined effect of rapid re-solidification and thermal stress caused by IPIB. The SEM cross-section images indicated that homogeneous modified layer with thickness up to 1.53 μm was produced and cracks inside sample were observed as well after IPIB irradiation. The evolution of cracks on surface of samples with pulse number was investigated in this work. Micro-holes distributed on the net structure of cracks were observed after IPIB irradiation and the evolution of size and number of micro-holes with pulse number was discussed.

Electrical conductivity enhancement of transparent silver nanowire films on temperature-sensitive flexible substrates using intense pulsed ion beam

Silver nanowire (AgNW) networks have attracted particular attention as transparent conductive films (TCF) due to their high conductivity, flexibility, transparency, and large scale processing compatible synthesis. As-prepared AgNW percolating networks typically suffer from high contact resistance, requiring additional post-synthetic processing. In this report, large area irradiation with 200 ns short intense pulsed ion beam (IPIB) was used to anneal and enhance the conductivity of AgNW network, deposited on temperature-sensitive polyethylene terephthalate (PET) substrate. A TCF sheet resistance shows irradiation dose dependence, decreasing by four orders of magnitude and reaching a value of 70 Ω/sq without damaging the polymer substrate, which retained a transparency of 94%. The IPIB irradiation fused AgNW network into the PET substrate, resulting in a great adhesion enhancement. Heat transfer simulations show that the heat originates at the near-surface layer of the TCF and lasts an ultra-short period of time. Obtained experimental and simulation results indicate that the irradiation with IPIBs opens new perspectives in the low-temperature annealing of nanomaterials deposited on temperature-sensitive substrates.

Investigation of the Effects of an Intense Pulsed Ion Beam on the Surface Melting of IN718 Superalloy Prepared with Selective Laser Melting

Intense pulsed ion beam irradiation on IN718 superalloy prepared with selective laser melting as an after-treatment for surface melting is introduced. It is demonstrated that intense pulsed ion beam composed of protons and carbon ions, with a maximum current density of 200 A/cm2 and a pulse length of 80 ns, can induce surface melting and the surface roughness changes significantly due to the generation of micro-defects and the flow of the molten surface. Irradiation experiments and thermal field simulation revealed that the energy density of the ion beam plays a predominant role in the irradiation effect—with low energy density, the flow of molten surface is too weak to smooth the fluctuations on the surface. With high energy density, the surface can be effectively melted and smoothened while micro-defects, such as craters, may be generated and can be flattened by an increased number of pulses. The research verified that for the surface melting with intense pulsed ion beam (IPIB), higher energy density should be used for stronger surface fluidity and a greater pulse number is also required for the curing of surface micro-defects.

Dynamic mechanism of crater formation induced by inclusion during intense pulsed ion beam irradiation

Crater is a general defect appeared on metallic target after intense pulsed ion beam (IPIB) treatment, which greatly limits the utilization and development of this technology. Understanding the mechanism of crater formation is of great significance for IPIB application. It is reported that inclusion in metallic target is associated with crater formation. In this work, the inclusions exposed to vacuum environment on target surface were found to lead to crater formation during 2.0 J/cm2 IPIB irradiation via a positioning observation experiment on high speed steel. To investigate the dynamic mechanism of crater formation, thermal conduction model and laminar flow model were performed successively. The flow field analysis revealed that surface tension coefficient difference between molten inclusion and molten matrix is the primary reason to drive melt flow and generate crater. In the subsequent evolution of the crater, surface curvature also plays an important part.

The influence of metal surface topography on ablation behavior during intense pulsed ion beam irradiation

As a flash heat source, intense pulse ion beam (IPIB) has extensive applications in material surface modification. The ablation effect during IPIB irradiation on target can impact the results of material modification. Therefore, the understanding of ablation mechanism is of great significance for IPIB application. In this work, to investigate the influence mechanism of surface topography on ablation behavior, pure zinc targets with different surface roughness were bombarded by IPIB with various energy densities at TEMP-4M accelerator. The experiments results showed that the ablation mass increased with the surface roughness increasing. Combining Monte Carlo method and finite element method, a heat conduction model was constructed to describe the ablation process of zinc target with different surface roughness. The simulation results agreed with the experiments, and the mechanism of ablation influenced by the surface topography was proposed.

Shielding of energy deposition by ablation of plastics under intense pulsed ion beam irradiation

With high power density in solid targets, intense pulsed ion beam with a pulse length of hundreds of ns and cross-sectional energy density of several J/cm2 may induce surface ablation and this effect can be used for thin-film preparation and nanopowder synthesis. Nevertheless, with ablation by the pulsed ion beam, the energy deposition of ions in targets may be affected and this further toughens the analysis of ablation and related material response in applications and ion beam diagnostics. In this study, the energy deposition of nanosecond pulsed ion beam composed of protons and carbon ions on stainless steel and plastics on BIPPAB-450 pulsed ion beam accelerator was investigated with infrared diagnostics. It is revealed that on plastics, under nanosecond IPIB irradiation with energy density of 1.5 J/cm2, ablation plume can be formed at the beginning stage of beam irradiation and the ablation plume may impose strong stopping to the ions in the pulsed ion beam and thus the energy deposition of the ion beam is shielded from reaching the target with over 80% of the beam energy screened. The influence of this energy shielding effect on applications such as beam measurement and material treatment was discussed reasonably.

The ablation of plastics by intense pulsed ion beam

With strong flash heating effects, intense pulsed ion beam (IPIB) may induce ablation on the solid surface and it is the basis of applications such as surface cleaning, nanopowder preparation and thin-film synthesis with IPIB. In this study, the ablation of polymethyl methacrylate (PMMA) by IPIB was investigated with varied beam energy density on pulsed ion beam accelerator BIPPAB-450 to study the ablation of IPIB under strong ablation. With thermal imaging measurement, it is revealed that when energy reaches a certain threshold, the ablation plume generated on the target surface may impose a shielding effect on the ion beam energy from depositing in the target. It is verified by thermal field simulation that for the low evaporation temperature and high thermal resistance, intense ablation plume may be generated on the surface of plastics under low IPIB energy density or at the early stage of IPIB irradiation. Ablation mass measurement demonstrated that under irradiation of IPIB with a pulse length of 120 ns, ion energy up to 450 keV, energy density up to 3.8 J/cm2, the mass loss of the target increases with the rise of IPIB energy density. Under the irradiation of a series of pulses, the mass loss of PMMA increases proportionally. Unlike ablation on metals by direct beam energy deposition, the ablation of plastics by IPIB endures more stages and the ablation may be more achieved by the heated ablation plasma by beam irradiation.

Influence of ablation on energy deposition in polymer material under irradiation of intense pulsed ion beam

Short-pulse length and high-power density, intense pulsed ion beam (IPIB) has been widely studied in material processing during past decades. Ablation effect plays a great role in the interaction between IPIB and material and may affect the energy deposition of IPIB, thus further influencing the beam application and diagnostics. Therefore, the investigation of ablation effect on energy deposition of IPIB in the irradiated material is of great significance for its applications and diagnostic techniques. In this work, experiments on the IPIB irradiation are carried out on the BIPPAB-450 accelerator at Beihang University. Its maximum accelerating voltage is 450 kV, peak current density is 150 A/cm<sup>2</sup>, energy density is 1.5–1.8 J/cm<sup>2</sup> and pulse duration (FWHM) is 80 ns. Polymer materials which have low thermal conductivity, low decomposition temperature and thus yield to ablation under low beam density, such as polycarbonate (PC), polyvinyl chloride (PVC) and polymethyl methacrylate (PMMA), are chosen in the present research. The 304 stainless steel is used for calorimetric beam diagnostics and comparative analysis. Energy deposition in polymer material and 304 stainless steel are obtained by high infrared imaging diagnostics. It is revealed that the distributions of energy deposition in these two kinds of materials differ from each other obviously. The highest energy density deposited in the 304 stainless steel appears in the center of the irradiated area where focused is the beam with a higher energy density. However, the central energy density in polymer material turns out to be lower than the surrounding area, indicating that a large portion of the ion beam is prevented from reaching the target. Meanwhile, the simulation based on the finite element method is carried out for the thermal filed distribution and evolution under the IPIB irradiation. The simulation result indicates that the strong ablation can be generated on the target surface since the highest temperature caused by IPIB irradiation is much higher than its decomposition temperature. According to the results of experiments and simulation, the polymer material can start to be ablated at the initial stage of IPIB irradiation which will consume partial energy and the products of ablation may act as shielding to block the energy deposition in the same pulse.

Surface vitrification of iron and FeCuNbSiB alloy irradiated by intense pulsed ion beam

Intense pulsed ion beam (IPIB) is an emerging flash heat source for surface modification of metal. In IPIB treatment, the formation of amorphous phase is always considered as a significant mechanism to modify and improve the surface properties of target, due to the excellent mechanical performance of amorphous alloy. Thus, the understanding of surface vitrification process and its conditions induced by IPIB irradiation is of great value for its application. In this work, pure iron and FeCuNbSiB alloy were chosen as target for investigation in term of the difference of their glass forming ability (GFA). XRD results showed that the measurable amorphous layer cannot be formed in the surface of both of these two alloys after IPIB irradiation. Thermal field and solute diffusion were studied using the finite element method. It is indicated that during the IPIB irradiation, the molten surface layer of FeCuNbSiB alloy is heterogeneous, and thus it has much lower GFA than the Fe-Cu-Nb-Si-B mixed system. It is proposed that the sufficient mixture of elements in the molten surface layer is indispensable for surface vitrification. In addition, the formation of craters and cracks on the surface will be harmful to form amorphous layer.

A Numerical Study of Cracks Appearance on Tungsten Surface After High Intense Pulsed Ion Beam Irradiation

Due to the outstanding physical properties, Tungsten has been proposed for use in the divertor of future fusion devices. However, tungsten shall face strong particle bombardment from the plasma, which causes severe damage to the material. The purpose of this work is to build such an accurate analytical model which can predict the damages in target material like crack production and propagation after high intense pulsed ion beam irradiation. Hence, a two-dimensional finite element method is used to study the effect of high intense pulsed ion beam on tungsten surface numerically. To judge temperature and stress distribution in material, thermal conduction model is combined with non-linear fracture mechanics model and J-Integral parameter is used as a criterion to judge the crack propagation. Simulation results reveal that different crack heights and sizes can affect the results and there is a critical depth for crack propagation. The model gives good results to real experimental observations and has potential applications for different intense pulsed electron/plasma beams and different target materials as well.

Anisotropy effect of crater formation on single crystal silicon surface under intense pulsed ion beam irradiation

Abstract Due to the induced extremely fast thermal and dynamic process, Intense Pulsed Ion Beam (IPIB) is widely applied in material processing, which can bring enhanced material performance and surface craters as well. To investigate the craters’ formation mechanism, a specific model was built with Finite Element Methods (FEM) to simulate the thermal field on irradiated single crystal silicon. The direct evidence for the existence of the simulated 6-fold rotational symmetric thermal distribution was provided by electron microscope images obtained on single crystal silicon. The correlation of the experiment and simulation is of great importance to understand the interaction between IPIB and materials.

Hydrodynamic effects on the surface morphology evolution of aluminum alloy under intense pulsed ion beam irradiation

As widely observed in many studies, the surface morphology of solids may change significantly after irradiation of intense pulsed ion beams (IPIB). This effect is crucial for surface treatments and may limit the utilization of IPIB as a novel method for surface processing in some cases. In present work, taking 6061 aluminum alloy for instance, the hydrodynamic behavior of the molten surface formed by IPIB irradiation was studied. By taking IPIB-induced heat transfer and level-set method flow field analysis with finite element method (FEM) it is revealed that under IPIB irradiation, the surface tension caused by the unevenness of curvature distribution of molten surface leads to mass transportation and a smoothening trend in the surface morphology evolution, meanwhile surface tension release is achieved. Irradiation of 6061 aluminum alloy was carried out and the trend in surface morphology evolution is consistent with the theoretical prediction.

Simulation analysis of zinc ablation process and mass by intense pulsed ion beam irradiation

AbstractAs the strong thermal effect in the surface, intense pulsed ion beam (IPIB) has been extensively used in material surface modification. The ablation is an important part in the interaction process between IPIB and material. In order to investigate the ablation mechanism, combined with IPIB dynamic energy spectrum and infrared imaging diagnostic results, a two-dimensional axisymmetric heat conduction model considering the effect of ablated material was constructed to describe the ablation process and calculate the lost mass of the targets. The influences of beam parameters and ablated matter on the ablation rate were discussed. The experimental and simulative results of ablation threshold and mass were compared.

Hydrodynamic Effects on Surface Morphology Evolution of Titanium Alloy under Intense Pulsed Ion Beam Irradiation**Supported by the National Natural Science Foundation of China under Grant No 1175012, the China Postdoctoral Science Foundation under Grant No 2016M600897, and the National Science and Technology Major Project of the Ministry of Science and Technology of China under Grant No 2013ZX04001-071.

The hydrodynamic effects of molten surface of titanium alloy on the morphology evolution by intense pulsed ion beam (IPIB) irradiation are studied. It is experimentally revealed that under irradiation of IPIB pulses, the surface morphology of titanium alloy in a spatial scale of μm exhibits an obvious smoothening trend. The mechanism of this phenomenon is explained by the mass transfer caused by the surface tension of molten metal. Hydrodynamic simulation with a combination of the finite element method and the level set method reveals that the change in curvature on the molten surface leads to uneven distribution of surface tension. Mass transfer is caused by the relief of surface tension, and meanwhile a flattening trend in the surface morphology evolution is achieved.

The tensile effect on crack formation in single crystal silicon irradiated by intense pulsed ion beam

Improving antifatigue performance of silicon substrate is very important for the development of semiconductor industry. The cracking behavior of silicon under intense pulsed ion beam irradiation was studied by numerical simulation in order to understand the mechanism of induced surface peeling observed by experimental means. Using molecular dynamics simulation based on Stillinger Weber potential, tensile effect on crack growth and propagation in single crystal silicon was investigated. Simulation results reveal that stress-strain curves of single crystal silicon at a constant strain rate can be divided into three stages, which are not similar to metal stress-strain curves; different tensile load velocities induce difference of single silicon crack formation speed; the layered stress results in crack formation in single crystal silicon. It is concluded that the crack growth and propagation is more sensitive to strain rate, tensile load velocity, stress distribution in single crystal silicon.

Craters forming mechanism of high speed steel irradiated by intense pulsed ion beam

Intense pulsed ion beam (IPIB) is regarded as a material surface treatment technology due to its energy compression in temporal and spatial scales. However, the craters induced by IPIB irradiation limit its application. Therefore, the study about the forming mechanism of craters is crucial for the development of this technology. In this work, craters on the surface of high speed steel after IPIB irradiation were studied. The analysis revealed that the inclusions in steel was contributed to crater formation. It was found that the feature of inclusions in steel determined the topography of craters on material surface directly. The surface thermal field simulation showed that the inclusions will be vaporized prior to adjacent matrix. Partial evaporization of inclusions have been certified to drive the melt flow forming craters. The result is useful to understand the forming mechanism of a sort of craters induced by IPIB on steel surface.

The Corrosion Behavior of Ni-Based Superalloy Irradiated by Intense Pulsed Ion Beam

Intense pulsed ion beam (IPIB) has been extensively used in the surface strengthening of metal materials in the past decades. Quite a lot of these materials need to be operated in the corrosive environment. Therefore, it is of significance to research the corrosion behavior of metal materials after IPIB irradiation. In this work, the corrosion behavior of Ni-based superalloy irradiated by IPIB in NaCl solution was studied. Compared to the original samples, after IPIB irradiation the corrosion resistance of samples were improved, and craters were formed on the surface of Ni-based super alloys. It is found that micro-areas with craters would be eroded prior to other areas in caustic solutions. The analysis revealed that craters play an important role in the corrosion process of the metal after irradiation. This research would help understand the influence of craters induce by IPIB on the operational performance of metal materials.