Ablation Plasma Research Articles

Study of atoms and multiply charged ions features in the nanosecond laser produced Mo plasma in vacuum using optical emission spectroscopy and time-of-flight electrostatic energy analyzer

The species including atoms and multiply charged ions in the laser produced molybdenum (Mo) plasma are investigated in this work using optical emission spectroscopy and time-of-flight electrostatic energy analyzer (TOF-EEA). Nanosecond laser (5 ns, 1064 nm,) pulses were focused on the Mo target surface with a spot size of 0.4 mm2, energy of ∼150 mJ/pulse (corresponding to a power density of ∼7.5 GW cm−2) to generate the Mo plasma in vacuum environment. Time-resolved spectral analysis was carried out to investigate the temporal evolution of continuous background, atomic, and monovalent ionic spectral signals. The Saha–Boltzmann method is applied for spectral fitting, providing insight into the temporal evolution of electron temperature (T e) and electron density (n e). Over the time from 40 ns to 500 ns, the T e decreases from 3.6 eV to 0.52 eV, and the n e decreases from 2.5 × 1020 cm−3–1.0 × 1015 cm−3. Linear fitting extrapolation predicts the T e and n e could be even up to 6.3 eV and 2.5 × 1022 cm−3, respectively, at the early stage of 10 ns. This indicates the generation of multiply charged ions during the laser ablation process. The multiply charged ions up to 6 charge states were observed by the TOF-EEA and the energy distributions for the different charged ions were also obtained. It was found the ion kinetic energy is positively related to the number of charge state indicates the existence of acceleration electric field. The equivalent accelerating potential is determined as approximately 570 V at the current laser power density. This research provides a significant reference for the establishment of models for laser ablation plasmas and a profound understanding of the underlying physical processes.

High Energy Pulsed Laser Beam to Produce a Thin Layer of Crystalline Silver without Heating the Deposition Substrate and Its Catalytic Effects

Crystalline silver thin layers were obtained using high-energy pulsed laser ablation without the heating of the deposition substrate. The fluid Plateau–Rayleigh (PRI), Rayleigh–Taylor (RTI), and Richtmyer–Meshkov (RMI) instabilities, as well as the crown splash induced during the pulsed laser deposition (PLD) in the high energy regime, resulting in ring and pearl-shaped structures, offer the benefit of an increased sorption surface. These morphological structures obtained for the silver thin layers make them of interest for catalytic applications. This study addresses both fundamental and applied issues on the morphological structures obtained for the silver thin layers and their catalytic function in organic processes. In this sense, the catalytic action of the thin silver layer was highlighted by modifications of the Reactive Blue 21 dye (C.I.) in an aqueous solution with sodium bicarbonate. Specific investigations and analyses were carried out using electron microscopy and elemental analysis (SEM-EDX), atomic force microscopy (AFM) and profilometry, mass spectrometry, ablation plasma diagnosis, diffractograms (XRD), as well as IR spectroscopy (FTIR). In addition to the experimental investigation and analyses, the simulation of the ionization energy threshold was conducted in COMSOL for complementary evaluation on the involved processes and phenomena.

An experimental study on low-temperature plasma tissue ablation and its thermal effect

Low-temperature plasma ablation has been recently used for minimally invasive surgeries. However, more research is still needed on its generation process during tissue ablation and the underlying mechanism of tissue thermal damage. In this paper, high-speed camera footage, voltage–current signal collection, temperature analysis, and histological analysis were used to investigate the dynamic process of plasma tissue ablation and its thermal effect of dual-needle electrodes immersed in normal saline, which were driven by a high-frequency DC power supply with an output voltage ranging from 220 V to 320 V and a squire wave of 100 kHz. Microbubbles occurred around the ground electrode and merged to form a vapor layer that could completely cover the ground electrode. Plasma capable of ablating tissue would occur in the vapor layer between the ground electrode and tissue. The effect of electrical parameters on plasma generation and its thermal effect are analyzed by statistical results. The experimental results indicated that the voltage applied to the electrodes significantly influenced both the generation and stability of plasma, as well as the heat generation and tissue damage around the electrodes. Furthermore, under the same voltage, the existence of biological tissue promotes the formation of a vapor layer around the electrode, thereby facilitating the generation and stability of plasma. Notably, the temperature rise around the ground electrode is much higher than that around the powered electrode. These results have direct application to the design of plasma tissue ablation systems, which could achieve tissue ablation effects with minimal thermal damage.

High sensitive detection of Cd, Hg, Pb and Cr in rice based on LA-MPT-OES with optimized excitation regions by two-dimensional characterization of plasma plume

Direct, rapid and highly sensitive detection of heavy metals in rice is essential to ensure food safety. In this research, a combination of laser ablation and microwave plasma torch optical emission spectrometry (LA-MPT-OES) was proposed. Based on the optimal observation positions, a high sensitivity and direct determination of Cd, Hg, Pb and Cr in rice were realized. The limits of detection (LOD) were 0.97, 0.12, 0.61 and 0.15 μg/kg, respectively, which were reduced by one order of magnitude compared to the optimal observation height. In addition, the LOD was reduced by one to two orders of magnitude compared with the techniques that require sample pre-treatment. Moreover, the results of the Certified Reference Materials and real samples were in agreement with the reference values with a relative error in the range of 0.28% ∼ 14.16%. The results demonstrated that LA-MPT-OES could be a promising tool to detect heavy metals in rice.

Study of ablation phase in double-wire Z-pinch based on optical Thomson scattering

Measurement of plasma parameters during the ablation phase in the Z-pinch is crucial for investigating the dynamic behaviors. In this study, optical Thomson scattering was employed to measure the temperature and velocity of the ablation plasma in a double-wire Z-pinch. The scattering spectra profiles were fitted using a model that considered the velocity distribution. The experimental results revealed the energy evolution of ablation plasma, the establishment of the global magnetic field and the development of axial non-uniformities. The precursor plasma was found to play a key role in strengthening the global magnetic field. A resistive layer near the wire core with a size of 1.5 mm was observed in the ablation plasma after the precursor plasma column formed. The plasma underwent rapid heating in this layer, the electron temperature rises from 17 eV to 22 eV. Upon leaving this layer, electron the temperature is stable at around 22 eV. The radial distribution of the ablation rate increases and decreases, indicating the axial motion of the ablation plasma, which could be caused by the tilt motion of the stream and the secondary modulation of the natural wavelength.

Pulsed plasma thruster exhaust reconstruction

The transient exhaust of an ablative pulsed plasma thruster is characterized experimentally for three capacitances and three discharge voltages, for discharge energies below 11 J. A novel analysis technique is introduced, which reconstructs the exhaust as a superposition of different Maxwellian-like ion groups. Each ion group is characterized by its own mean velocity, thermal spread, initial density, generation time and divergence rate. The time series of three probes working in the ion saturation regime are used to determine the model parameters by least-squares fitting. This approach allows a higher level of accuracy and insight than time-of-flight analysis based on direct feature correlation alone. A good fit of the main part of the discharge time series is achieved with just three ion groups, with mean velocities ranging in 50–70, 30–45 and 10–25 km s−1 respectively. Each ion group differs in the lateral divergence rate and axial thermal spread, and potentially corresponds with a different charge/mass ratio and/or creation time. Some trends with bank capacitance and discharge voltage are identified and discussed.

Study of the pellet ablation cloud using the tomography technique for two-directional simultaneous photography in GAMMA 10/PDX

The pellet ablation mechanism is an interesting subject for plasma fuelling in fusion plasmas. In GAMMA 10/PDX, pellet injection experiments for higher density plasma production are planned to conduct detached plasma experiments in the higher density plasma condition. We measured the pellet ablation cloud by using the two-directional simultaneous photography system in GAMMA 10/PDX. The tomography reconstruction technique was used for considering the pellet trajectory in the plasma and pellet ablation. The three-dimensional pellet trajectory and pellet ablation images in the plasma were clearly obtained for the first time, to the best of our knowledge.

Influence of a Hypersonic Ablative Plasma Wake-Field on the Performance of a Vivaldi Antenna

Influence of a Hypersonic Ablative Plasma Wake-Field on the Performance of a Vivaldi Antenna

KrF laser-driven shock tube: Realization and first experiments

We report on the first implementation of a miniature laser-driven shock tube (LDST) of 5 × 5 mm cross section and 50-mm length for generating and studying strong shock waves (SW) and hypersonic gas flows with M > 10. Operation of the LDST is based on the acceleration of a thin CH-film by ablative plasma pressure produced when the film is irradiated by high-energy UV pulse of the GARPUN KrF laser (100 J & 100-ns). The film serves as a piston that pushes a SW in the gas filling the LDST. An optical system based on a multi-element prism raster provides focusing of KrF laser beam into 7 × 7 mm square spot with 100 J/cm2 energy fluence (1 GW/cm2 intensity) with inhomogeneity ∼3 % across the LDST aperture. It is expected that the LDST with KrF laser driver can be an effective tool for studying hydrodynamic phenomena, such as hydrodynamic instabilities and transition to a turbulence, hypersonic gas flow around bodies, reflection and cumulation of strong SW.

Non-ferrous metal of the Bronze Age of Northern Kazakhstan: geochemical characteristics and ore base

The chemical composition of 29 copper and bronze artifacts from the sites of the Petrovka and Alakul Cultures located be-tween the Tobol and Ishim Rivers (the burial grounds of Bekteniz and Dzhangildy 5, and the sites of Novonikolskoye 1 and Semioz-ernoye 2; Northern Kazakhstan) were analysed using mass spectrometry with inductively coupled plasma and laser ablation. The sites are 14C dated to the interval between the 19th–17th centuries BC. In the examined sample, the leading metallurgical group with a slight prevalence in both Petrovka and Alakul metals was “pure” copper; the second part of the metal was represented by tin bronzes — low-alloyed (up to 8 wt.% Sn) in the Petrovka, and high-alloyed (Sn up to 21 wt.%) in the Alakul Culture. The statistical analysis of the main components of trace elements in the metal demonstrated a division into six main geochemical groups. Among these, tin bronzes with an uninterpretable copper component (10 specimens), “pure” copper of Ural origin with Fe-Co-Ni-As-Zn correlations (9 specimens), and “pure” copper with polymetallic Sn-Pb-As-Ag-Se specialization (10 copies), corresponding to the ores of copper deposits of the Kokshetau anticlinorium, can be identified. An overview of the tectonic structures of Northern Ka-zakhstan shows the nearby presence of several porphyry copper and skarn deposits with ancient mines (Imantau, Baksinskoye, Akkan-Burlukskoye, etc.), which likely served as sources of copper ore. Closely associated with these are Greisen and quartz-vein-greisen tin deposits, but there is no reliable information about their use in ancient times. According to the composition of tin alloys in the analysed metal, two main types can be distinguished: tin (without correlation with other impurity elements) when using pure cassiterite, and tin-lead (with increased concentrations and correlation of As, Au, Bi, etc.) when using cassiterite-sulfide ores. The data show the association of the Bronze Age sites of Northern Kazakhstan with the ore and raw materials base in this region, and the intensity of trade exchange of metallurgical products between the Ural and Kazakhstan centers of metal production.

C/C-HfC-SiC composites with simultaneous the resistance to ultra-high temperature airflow erosion and high temperature oxidation

HfC-SiC modified C/C composites containing in situ formed Si-HfC-HfSi2 ablation resistant layer and SiC oxidation resistant layer were successfully prepared by reactive melt infiltration (RMI) combined with gaseous silicon infiltration (GSI). A comparative study was conducted on the anti-oxidation and anti-ablation performance of the C/C-HfC-SiC composites with GSI (noted as RG-CHS) and without GSI (noted as R-CHS). After oxidation at 1,500 °C for 200 min, the oxide film of RG-CHS remained intact. The mass and linear ablation rates decreased from 1.31 mg/s and 7.36 μm/s to 0.12 mg/s and −0.22 μm/s after GSI process, respectively. The introduction of low melting point phases and reducing surface defects can improve the high temperature oxidation resistance and plasma ablation resistance of the composites.

АРТРОСКОПИЧЕСКАЯ ХОЛОДНО-ПЛАЗМЕННАЯ АБЛЯЦИЯ ПРИ РЕДКИХ ЗАБОЛЕВАНИЯХ СИНОВИАЛЬНОЙ ОБОЛОЧКИ КОЛЕННОГО СУСТАВА. КЛИНИЧЕСКИЕ НАБЛЮДЕНИЯ

Background. Over a long period, an open capsular synovectomy technique was recommended for villous nodular synovitis and synovial chondromatosis of the knee joint. However, such surgical treatment is accompanied by significant trauma to the joint tissue and frequent postoperative recurrence. Currently, it is advisable to assess the possibilities of modern treatment methods (arthroscopic cold plasma ablation) for rare diseases of the knee joint. The aim of the study. To assess the possibilities of arthroscopic cold plasma ablation in a series of clinical observa-tions of the surgical treatment of patients with rare diseases of the knee joint synovium in a statistically small sample. Material and methods. Surgical treatment was performed in 14 patients with diseases of the knee joint synovium. We carried out clinical and radiological examinations, computed tomography and magnetic resonance imaging, multi-detector computed tomographic angiography, ultrasound examination, Dopplerography of the vessels of the lower extremities, biochemical examination of synovial fluid, arthroscopy with targeted biopsy and subsequent morphological examination of the synovial membrane. Results. In 7 patients with pigmented villous nodular synovitis, the following surgeries were performed: in 1 patient with the diffuse form – an open subtotal capsular sinovectomy; in 6 patients with the nodular form – an arthroscopic partial cold plasma capsular sinovectomy of the knee joint. In 7 patients with synovial chondromatosis, an arthroscopic removal of cartilage flaps and partial cold plasma ablation of synovial folds and knee joint villi were carried out. Conclusion. Arthroscopic cold plasma ablation with bipolar electrodes in various modes of the Qvantum-2 (Arthro-Care, USA) using anterior, posterolateral and suprapatellar approaches makes it possible to carry out less traumatic and radical, without damaging deep layers of cartilage and capsule, surgical treatment of rare diseases of the knee joint synovium. In diffuse forms of pigmented villous nodular synovitis, it is advisable to continue comparative studies of various surgical methods of capsular sinovectomy (open and arthroscopic techniques).

Transparent Structures for ZnO Thin Film Paper Transistors Fabricated by Pulsed Electron Beam Deposition.

Thin film transistors on paper are increasingly in demand for emerging applications, such as flexible displays and sensors for wearable and disposable devices, making paper a promising substrate for green electronics and the circular economy. ZnO self-assembled thin film transistors on a paper substrate, also using paper as a gate dielectric, were fabricated by pulsed electron beam deposition (PED) at room temperature. These self-assembled ZnO thin film transistor source-channel-drain structures were obtained in a single deposition process using 200 and 300 µm metal wires as obstacles in the path of the ablation plasma. These transistors exhibited a memory effect, with two distinct states, "on" and "off", and with a field-effect mobility of about 25 cm2/Vs in both states. For the "on" state, a threshold voltage (Vth on = -1.75 V) and subthreshold swing (S = 1.1 V/decade) were determined, while, in the "off" state, Vth off = +1.8 V and S = 1.34 V/decade were obtained. A 1.6 μA maximum drain current was obtained in the "off" state, and 11.5 μA was obtained in the "on" state of the transistor. Due to ZnO's non-toxicity, such self-assembled transistors are promising as components for flexible, disposable smart labels and other various green paper-based electronics.

Ablation performance and mechanism of fibrous monolithic ZrB2-SiC ceramics prepared by wet-spinning co-extrusion method under plasma flame

The fibrous monolithic structure exhibits extensive graded fracture as well as load redistribution upon fracture due to the unique layered microstructure, providing an effective way to toughen ceramic materials. In this work, fibrous monolithic ZrB2-SiC/SiCw (FZSw) and fibrous monolithic ZrB2-SiC/BN ceramics (FZB) were prepared by wet-spinning and co-extrusion method using SiCw and BN as the interfacial layer. The strengths, toughness, and the work of rupture of FZSw were 117 MPa, 3.9 MPa m1/2, 104 J/m2, while that of FZB were 103 MPa, 2.6 MPa m1/2, 98 J/m2, respectively. FZSw and FZB were subjected to 200 s plasma ablation tests under 12.84 MW/m2 and plasma flame above 3000 °C. The mass and linear ablation rates of FZSw after testing were -0.34 mg/s and -0.2 μm/s, respectively, and remain intact, showing non-ablation characteristics, while FZB underwent delamination and destruction. The introduction of SiCw interface layer improved the thermal conductivity of FZSw and reduced the surface temperature of FZSw. Higher oxidation temperature and higher SiC content of the SiCw interface layer result in a great quantity of SiO2, which effectively isolated oxygen from further erosion.

Spatiotemporal characterization of cerium monoxide in laser ablation plasmas using spectrally-resolved fast-gated imaging

Previously unidentified CeO hot bands and fundamental insights into the plasma-gas intermixing dynamics of laser ablation plasmas are presented.

Trends for development of processes and machines for strengthening coatings deposition

Results of analysis of "International Conference of Advanced Coatings and Films" literature, which was organized by Institute of advanced coatings and materials in Taizhou university of China were represented. Wear resistance and solid lubricated and antifriction coatings including DLC ta-C coating and combination of a-C:Н sublayer and MoS2 layer were considered. Improve ways of coatings deposition methods, such as microwave PECVD, super HIPIMS, HIPIB ablation plasma were analyzed. Methods of slide friction reduction by laser grain-orientating of steel surface and achieve of super lubrication properties of materials by thin film coatings were shown. A peculiarity of vacuum coaters for strengthening coatings deposition development by Chinese enterprises were analyzed.

Burst laser ablation in distilled and heavy water

The laser water ablation initiates several physical effects: ionization of atoms and optical breakdown of the liquid, phase explosion and cavitation, shockwave propagation, and even the potential to yield neutrons. The goal of this paper is to compare ablation plasma glow and thermal changes in distilled and heavy water under single pulses and bursts of ultrashort laser pulses. The laser ablation was performed beneath the water surface in a circular laser scanned trajectory. There were two regimes of water ablation: burst regime and single pulses ablation. The absorption processes and ablation plasma glow were evaluated with visible and infrared cameras, fast silicon detector and thermocouple. The study revealed that the heavy water ablation process is 3.5 times more intense in the burst regime with the same laser power. Unexpectedly, the plasma glow with a lower power density of laser 2.6·1013 W/cm2 was four times higher than with higher power density of 8·1013 W/cm2. In burst mode and at a higher power density, heavy water produced nearly two times higher plasma glow.

Effects of deposition temperature on microstructures and ablative properties of SiC coatings prepared by CVD from methylsilane

Using the methylsilane (MS) as a gas precursor, SiC coatings were prepared on the surface of graphite by the chemical vapor deposition (CVD) method at different deposition temperatures. The effects of temperature on the deposition rate, microstructures and ablative properties of SiC coatings were investigated systematically. The results showed that the SiC deposition rate of SiC coating using MS at 1000 °C was 50–120 μm/h, which was much higher than that using methyltrichlorosilane (5–10 μm/h). The SiC coatings deposited at lower temperatures (900–1000 °C) exhibited smooth and spherical compact packing morphology, while the SiC coatings deposited at higher temperatures (1100–1200 °C) appeared to possess an irregular cauliflower morphology with an significantly increased size of SiC particles. Therefore, the SiC coating prepared at deposition temperature of 1000 °C had suitable density, roughness, and uniform size of coating microstructure. Meanwhile, the mass ablation rate and linear ablation rate of the obtained SiC coating were respectively 0.0096 mg/s and 0.3750 μm/s after plasma ablation at 2300 °C for 80 s, exhibiting excellent ablative resistance. This study provided a theoretical and technical foundation for the preparation of SiC coating using the MS as the gas precursor by the CVD method.

Observation of laser ablation of silicon as a function of pulse length at constant fluence via time-resolved x-ray spectroscopy

We investigate the ablation of silicon as a function of laser pulse length at a constant fluence using time-resolved x-ray spectroscopy data obtained from OMEGA EP experiments at the University of Rochester's Laboratory for Laser Energetics. Our targets consisted of three-layer planar structures composed of Si (50 μm), Cu (25 μm), and SiO2 (500 μm) layers. The Si layer was irradiated by a 351-nm laser with varying pulse widths of 250 ps, 500 ps, 1 ns, and 10 ns while maintaining a constant fluence of ∼27.9 kJ/cm2. Electron temperatures and densities of the ablated plasma were determined by analyzing the time-resolved x-ray spectroscopy data through a comparison of experimental measurements with synthetic results obtained from Si atomic calculations in a steady state and non-local thermodynamic equilibrium. These calculations were computed using PrismSPECT [MacFarlane et al., High Energy Density Phys. 3, 181 (2007)]. Additionally, radiation-hydrodynamics simulations with FLASH are used to generate simulated plasma-density and plasma-temperature profiles, which are then compared with the experimental measurements. Our analyses reveal that increasing the laser pulse length at a constant fluence results in a decrease in electron temperatures and densities. Furthermore, the longer pulses with lower intensities lead to deeper ablation regions before reaching the peak ablation but lower ionization balances in the silicon layer. These findings emphasize the critical role of laser pulse length in plasma ablation and shock generation for laser-impulse studies.

Mechanical and plasma ablation properties of double-interface fibrous ZrB2-SiC ceramics for ultra-high-temperature application

Double-interface fibrous ZrB2-SiC ceramics (DZSw) were prepared by wet-spinning and hot-pressing. The introduction of double-interface layers improves the interface bonding and crack tolerance making the bending strength and toughness of DZSw increased to 607 MPa and 6.3 MPa m1/2, respectively. After ablation testing in 9.34 MW/m2 plasma flame, DZSw remained intact, with linear and mass ablation rates of − 0.3 µm s-1 and − 0.11 mg s-1, respectively. However, single-interface fibrous ZrB2-SiC ceramic (SZSw) produced penetrating cracks, so DZSw presented high ablation resistance than SZSw. The introduction of a dense ZrB2-SiC outer interface layer in DZSw interrupts the three-dimensional connected structure of the porous SiCw interface layer in SZSw and consequently reduces the oxygen diffusion rate of the ceramics. Moreover, the high emissivity and thermal conductivity enable DZSw to serve in the high heat flux ablation environment caused by faster flight speed.