Plasma Shock Research Articles

Effects of changing thermal conductivity on photothermal excitation in non-local semiconductor material subjected to moisture diffusion and laser pulses

A novel model is presented in this study for the situation of wave interference in a non-local stimulated semiconductor medium, including thermal, plasma, and elastic waves. Moisture diffusion in one dimension (1D) has been included in the governing equations by varying the non-local medium's thermal conductivity under the impact of laser pulse according to the non-Gaussian temporal profile. The dimensionless model was characterized by linear transformations. Analytical solutions were obtained by applying Laplace transforms to a description of the governing equations based on the photo-thermoelasticity theory based on moisture diffusivity and variable thermal conductivity. When applying certain of the circumstances (thermal ramp type and non-Gaussian plasma shock), linear solutions are achieved in the time domain using various numerical techniques based on inverse Laplace transforms. Some of the physical variables being studied are visually shown via numerical simulation. The present investigation has produced numerous important concrete instances. Using graphs and theoretical descriptions, several contrasts are drawn, while certain physical factors, such as relaxation durations, changing thermal conductivity, non-local parameters, and reference moisture values, are in play.

New possibilities of cell and shock wave therapy in erectile function recovery in patients after radical prostatectomy: a review

For the first time in 2021, prostate cancer took 1st place among other oncological diseases in Western countries. Radical prostatectomy is still the method of choice among the prostate cancer radical therapy. An important unresolved problem remains the rehabilitation, since the overwhelming number of patients in the postoperative period develop sexual dysfunction, urination disorders, which significantly reduces the quality of life. Thus, this condition actualizes the search and development of new approaches to the therapy of erectile function after radical prostatectomy. This literature review presents the results of a literary search of Russian and international databases on the erectile function recovery after radical prostatectomy using platelet rich plasma and extracorporeal shock wave therapy.

Photothermal excitation in non-local semiconductor materials with variable moisture thermal conductivity according to moisture diffusivity

In this work, a new model is described for the case of interference between thermal, plasma and elastic waves in a non-local excited semiconductor medium. The governing equations have been put under the influence of moisture diffusion in one dimension (1D) when the moisture thermal conductivity of the non-local medium is taken in variable form. Linear transformations were used to describe the dimensionless model. The photo-thermoelasticity theory according to moisture diffusivity was applied to describe the governing equations using Laplace transforms to obtain analytical solutions. In the time domain, complete solutions are obtained linearly when the conditions are applied (thermal ramp type and non-Gaussian plasma shock) to the surface through numerical methods of inverse Laplace transforms. Numerical simulation is used to display the basic physical quantities under study graphically. The current research has yielded several specific examples of great significance. Many comparisons are made under the influence of fundamental physical variables such as relaxation times, variable thermal conductivity, non-local parameters, and reference moisture parameters through graphing and describing them theoretically.

Influences of spatial structure of plasma shock wave on electromagnetic wave propagation characteristics

Plasma shock waves represent high-speed, nonlinear motion states of plasma in which the physical parameters of fluid, such as density, temperature, and velocity, vary dramatically within a limited space. These variations make studying electromagnetic wave propagation in plasma shock waves difficult. In this study, we calculate the spatial distribution of the plasma frequency and collision frequency in the plasma shock layer based on the one-dimensional structure of the plasma shock wave. In the process from upstream to downstream of the plasma shock wave, the plasma frequency increases as a function of electron density; downstream, the plasma frequency increases as a function of the free stream Mach number, while the collision frequency decreases first and then increases. We also use the recursive convolution finite-difference time-domain method to calculate the propagation of the electromagnetic wave in the plasma shock layer. The absorption of the plasma shock layer to the electromagnetic wave decreases gradually as a function of the electromagnetic wave frequency. The absorption of the plasma shock layer downstream of the electromagnetic wave is greater than that upstream owing to the larger plasma frequency. In the case of low-Mach numbers, the wavelength of the electromagnetic wave downstream is larger than that upstream. In the case of high-Mach numbers, the thickness of the entire shock layer is much greater than that at low-Mach numbers. Due to the nonlinear effects of electromagnetic processes in plasmas, a modulation phenomenon occurs when electromagnetic waves propagate in the shock layer. In the case of low frequencies, the electromagnetic wave gave rise to a modulation phenomenon that resembled the beat phenomenon. When the electromagnetic wave frequency increased, a modulation phenomenon gradually appeared that resembled the oscillation superimposed on a sine wave. Further increases in the electromagnetic wave frequency led to the gradual disappearance of the modulation phenomenon.

WITHDRAWN: Effets synergiques des concentrés plaquettaires autologues et des ondes de choc extra-corporelles dans le traitement des pseudarthroses aseptiques diaphysaires des os longs

IntroductionUnion of long bone fractures is a complicated biological mechanism affected by numerous systemic and local variables. Disruption of any of these components may result in fracture nonunion. There are various types of clinically available treatment strategies for aseptic nonunion. Both activated platelet plasma and extracorporeal shock waves play important roles in fracture healing. This study aimed to investigate the interaction of Platelet-rich plasma (PRP) and extracorporeal shock wave (ESW) in bone healing of nonunion. HypothesisPRP and ESW have synergistic effects in treating long bone nonunion. MethodsBetween January 2016 and December 2021, a total of 60 patients with established nonunion of a long bone (18 tibias, 15 femurs, 9 humerus, 6 radii, and 12 ulnae) were included in this study, comprising 31 males and 29 females, ranging from 18 to 60 years old. Patients with bone nonunion were separated into two groups: PRP alone (Monotherapy group) and those treated with PRP combined with ESW (Combined treatment group). The two groups were compared to assess the therapeutic benefits, callus development, local problems, bone healing time, and Johner Wruhs functional classification of operated limbs. ResultsFifty-five patients were followed up, 5 patients were lost to follow-up, two in the PRP group and three in the PRP+ESW group, the follow-up time varied from 6 to 18 months, with an average of 12.7±5.2months. At 8, 12, 16, 20, and 24weeks following intervention, the callus score in the monotherapy group was significantly lower than in the combined treatment group (p<0.05). Both groups had no swelling and infection in the soft tissue of the nonunion operation site. In the PRP+ESW group, the fracture union rate was 92.59 % and the healing time was 16.3±5.2 weeks. In the PRP group, the fracture union rate was 71.43 % and the healing time was 21.5±3.7 weeks. The clinical healing time of the monotherapy group was significantly longer than the combined treatment group (p<0.05). All the nonunion patients with no signs of healing were treated with revision surgery. The excellent and good rate of Johner-Wruhs functional classification of affected limbs in the monotherapy group was significantly lower than in the combined treatment group (p<0.05). ConclusionPRP combined with ESW has a certain synergistic effect in treating aseptic nonunion after fracture surgery. It can significantly improve the formation of new bone, it is a minimally invasive and effective strategy to treat aseptic nonunion in a clinical setting. Level of evidenceIII, retrospective, single-centre, case-control study.

Anomalous coupling in radiation mediated shocks

We summarize recent attempts to unravel the role of plasma kinetic effects in radiation mediated shocks. Such shocks form in all strong stellar explosions and are responsible for the early electromagnetic emission released from these events. A key issue that has been overlooked in all previous works is the nature of the coupling between the charged leptons, that mediate the radiation force, and the ions, which are the dominant carriers of the shock energy. Our preliminary investigation indicates that in the case of relativistic shocks, as well as Newtonian shocks in multi-ion plasma, this coupling is driven by either, transverse magnetic fields of a sufficiently magnetized upstream medium, or plasma microturbulence if strong enough magnetic fields are absent. We discuss the implications for the shock breakout signal, as well as abundance evolution and kilonova emission in binary neutron star mergers.

Improving the Wear and Corrosion Resistance of Aeronautical Component Material by Laser Shock Processing: A Review.

Since the extreme service conditions, the serious failure problems caused by wear and corrosion are often encountered in the service process for aeronautical components. Laser shock processing (LSP) is a novel surface-strengthening technology to modify microstructures and induce beneficial compressive residual stress on the near-surface layer of metallic materials, thereby enhancing mechanical performances. In this work, the fundamental mechanism of LSP was summarized in detail. Several typical cases of applying LSP treatment to improve aeronautical components' wear and corrosion resistance were introduced. Since the stress effect generated by laser-induced plasma shock waves will lead to the gradient distribution of compressive residual stress, microhardness, and microstruture evolution. Due to the enhancement of microhardness and the introduction of beneficial compressive residual stress by LSP treatment, the wear resistance of aeronautical component materials is evidently improved. In addition, LSP can lead to grain refinement and crystal defect formation, which can increase the hot corrosion resistance of aeronautical component materials. This work will provide significant reference value and guiding significance for researchers to further explore the fundamental mechanism of LSP and the aspects of the aeronautical components' wear and corrosion resistance extension.

Review on Anti-Fatigue Performance of Gradient Microstructures in Metallic Components by Laser Shock Peening

Laser-shock-peening technology is an international research hotspot in the surface-strengthening field, which utilizes the mechanical effects of laser-induced plasma shock waves to effectively improve the fatigue performance of metallic components by introducing the gradient microstructures and compressive residual stress into the surface layer of processed materials. The fatigue failure caused by high-frequency vibrations in aeroengines during service is the most important threat to flight safety, and this case is more prominent for military aeroengines because their service situation is harsher. The present paper focuses on components such as high-temperature components, fan/compressor blade, and thin-walled weldments, and it systematically introduces the researching findings about surface nanocrystallization and compressive residual stress formation mechanism in typical aeronautical metallic materials treated by laser shock peening. The contents mainly involve the characteristics, formation process, fatigue resistance mechanism, thermal stability of residual compressive stress, and nanocrystallization generated by laser shock peening.

The Fundamental Mechanisms of Laser Cleaning Technology and Its Typical Applications in Industry

Laser cleaning is an advanced surface-cleaning technology that can lead to the instant evaporation and stripping of the attachments found on a substrate’s surface, such as contaminants, rust, and coatings; it uses a high-energy laser beam to irradiate the components’ surface. Compared with common surface-cleaning technologies, laser cleaning has the advantages of precision, efficiency, and controllability. In this paper, the fundamental mechanisms of laser cleaning technology are summarized in detail; these include the laser thermal ablation mechanism, the laser thermal stress mechanism, and the plasma shock wave mechanism. The operational principles, characteristics, and application range of each mechanism are discussed. Their typical applications in industry are outlined according to the differences in the substrate materials used, including metallic materials, nonmetallic materials, and semiconductor elements. This study provides a significant reference and guiding basis for researchers to further explore the fundamental mechanisms of laser cleaning, as well as various aspects of the typical industrial applications of laser cleaning.

On the propagation and interaction of ion-acoustic solitary, periodic, shock, and breather waves in a non-Maxwellian electron–positron–ion magnetoplasma

This investigation analyzes the propagation of nonlinear ion-acoustic waves (IAWs) in an unmagnetized, collisionless plasma composed of inertial positive ions and inertialess Maxwellian positrons as well as the inertialess non-Maxwellian electrons that obey (r, q)-distribution. To observe the impact of particle trapping on the nonlinear IAWs in an electron–positron–ion plasma, the Korteweg–De Vries (KdV) and modified KdV (mKdV) equations are derived using a reductive perturbation method. In the distribution function, the spectral parameters (r, q) put up their contribution to the flatness and high-energy tails, respectively. An important aspect of this investigation is the determination of well-known quasi-periodic solutions, multi-soliton solutions, breathers, and shocks under the variation of different physical parameters, especially spectral indices (r, q). Finally, the interaction of solitons is also presented for discussion of the complete profile. In addition, a detailed comparison, especially in a periodic wave, is made between the generalized (r, q)-distribution and the limiting cases of Kappa and Maxwellian distributions. The results presented in this study contribute to a better understanding of the characteristics of both high- and low-energy parts of the electron distribution function as well as the formation of periodic, soliton, multi-soliton, breathers, and shocks in space and astrophysical plasmas.

Comparison of efficacy of platelet-rich plasma and extracorporeal shock wave for the treatment of chronic insertional Achilles tendinopathy

To compare clinical efficacy of platelet-rich plasma (PRP) and extracorporeal shock wave in treating chronic insertional Achilles tendinopathy. From February 2019 to August 2021, 42 patients with chronic insertional Achilles tendinopathy were selected and divided into PRP group(20 patients, 28 feet) and shock wave group (22 patients, 29 feet). In PRP group, there were 12 males and 8 females, aged 47.00(28.00, 50.75) years old, and the courses of disease ranged 7.00(6.00, 7.00) months;PRP injection was performed in the Achilles tendon stop area of the affected side. In shock wave group, there were 16 males and 6 females, aged 42.00(35.75, 47.25) years old;and the courses of disease was 7.00(6.00, 8.00) months;shock wave was performed in Achilles tendon stop area of the affected side and triceps surae area. Visual analogue scale (VAS) and Victorian Institute of Sport Assessment-Achilles (VISA-A) were applied to evaluate clnical effect before treatment, 1, 3 and 6 months after treatment, and satisfaction of patients was investigated. VAS and VISA-A score in both groups were significantly improved at 1, 3 and 6 months after treatment than before treatment (P<0.05), VAS and VISA-A score in PRP group at 6 months after treatment were significantly higher than those at 1 and 3 months after treatment, and VAS and VISA-A score in shock wave group were lower than those at 1 and 3 months after treatment (P<0.05). There was no significant difference in VAS and VISA-A score between two groups before treatment, 1 and 3 months after treatment(P>0.05), while VAS and VISA-A score in PRP group were better than those in shock wave group at 6 months after treatment(P<0.05), and the satisfaction survey in PRP group was better than that in shock wave group(P<0.05). PRP injection has a good clinical effect on chronic insertional Achilles tendinopathy with high patient satisfaction, and medium-and long-term effect of PRP injection for the treatment of chronic insertional Achilles tendinopathy is better than that of extracorporeal divergent shock wave.

Support for the standard picture of thermal X-rays in the wind of ζ Puppis from dielectronic recombination of He-like ions

ABSTRACT We use the line ratios of resolved X-ray resonance and satellite line pairs from Si xiii and Mg xi ions to test the widely held assumption that the shocked plasma in the wind of hot stars is in collisional ionization equilibrium. We specifically apply this test to the prototypical O supergiant ζ Puppis, as its line ratios are well resolved in its total 813 ks Chandra observation. This satellite-to-resonance line ratio is known to be a reliable diagnostic of plasma temperature but has yet to be applied to hot stars due to needing a long exposure time to see both lines above the continuum. In testing the assumed plasma state, we also provide evidence against significant ionization and excitation from proton collisions. Since dielectronic recombination (DR) allows somewhat lower energy free electrons to excite resonance lines than by the usual collisional pathways, we also use the DR flux ratios to extend diagnostics of the ionization fraction of the parent ion to lower temperatures than any other method can achieve. Also, the DR ratio supports a concept of an average free electron temperature, for each target ion used, which can constrain heating models.

Enhancement of underwater shock wave by coupling electrical explosion and al-powder-suspension combustion: Facing advanced reservoir stimulation technology

The development of fossil energy requires eco-friendly and high-efficient approaches, especially in contemporarily low-carbon scenarios. Using the high-power pulsed discharge to induce fractures has drawn increasingly academic and industrial attention in reservoir stimulation. Therein, the electrical wire explosion is commonly adopted as the pulsed discharge load to transfer electrical energy to mechanical one (shock wave and plasma bubble) efficiently. To strengthen mechanical loadings, a discharge capsule with a metallic wire inside Al-powder suspension has been designed and tested. Experiments were performed with a μs-timescale pulsed power source with stored energy from 150 to 750 J, and the electrical explosion were diagnosed via high-speed photography, electrophysical, and mechanical measurements. The experiment shows that there is an optimal concentration of Al-powder suspension in order to obtain the maximum peak pressure of shock wave for a given discharge condition. Too high or low concentrations of the aluminum powder will cause a lower peak pressure. This paper shows that at the stored energy of 500 J, when the concentration of Al-powder suspension is 20 g/L, the peak pressure can reach 4.81 ± 0.27 MPa, which is 2.01 times as large as the shock wave generated by the electrical explosion under the same conditions in pure water. Through the electrophysical measurement, it is found that the aluminum powder almost does not affect the phase transition of the wire. However, in the subsequent plasma formation, the gaseous reaction products make the discharge channel more complex and in a higher pressure density state, which is shown by the increase of channel resistance. Through the backlit images taken by the high-speed camera, it is obvious that two discrete strong shock waves can be seen in the Al-powder-suspension environment.

Mechanism of paint removal by nanosecond pulsed laser plasma shock: simulation and experiment.

This paper establishes a new theoretical paint removal model of plasma shock based on Fabbro's model and Newton's second law. A two-dimensional axisymmetric finite element model is established to calculate the theoretical model. By comparing the theoretical and experimental results, it is found that the theoretical model can accurately predict the threshold of laser paint removal. It is indicated that plasma shock is an essential mechanism in laser paint removal. The threshold for laser paint removal is approximately 1.73J/c m 2. The experiments show that, with the increase of the laser fluence, the effect of laser paint removal first increases and then decreases. With the increase of the laser fluence, the paint removal effect is improved due to the increase of the paint removal mechanism. The competition between the plastic fracture and pyrolysis leads to a reduction in paint effectiveness. In summary, this study can provide a theoretical reference for studying the paint removal mechanism of plasma shock.

Experimental Measurements of Ion Diffusion Coefficients and Heating in a Multi-Ion-Species Plasma Shock.

Collisional plasma shocks generated from supersonic flows are an important feature in many astrophysical and laboratory high-energy-density plasmas. Compared to single-ion-species plasma shocks, plasma shock fronts with multiple ion species contain additional structure, including interspecies ion separation driven by gradients in species concentration, temperature, pressure, and electric potential. We present time-resolved density and temperature measurements of two ion species in collisional plasma shocks produced by head-on merging of supersonic plasma jets, allowing determination of the ion diffusion coefficients. Our results provide the first experimental validation of the fundamental inter-ion-species transport theory. The temperature separation, a higher-order effect reported here, is valuable for advancements in modeling HED and ICF experiments.

Relativistic Collisionless Shocks in Inhomogeneous Magnetized Plasmas

Relativistic collisionless shocks are associated with efficient particle acceleration when propagating into weakly magnetized homogeneous media; as the magnetization increases, particle acceleration becomes suppressed. We demonstrate that this changes when the upstream carries kinetic-scale inhomogeneities, as is often the case in astrophysical environments. We use fully kinetic simulations to study relativistic perpendicular shocks in magnetized pair plasmas interacting with upstream density perturbations. For amplitudes of δ ρ/ρ ≳ 0.5, the upstream fluctuations are found to corrugate the shock front and generate large-scale turbulent shear motions in the downstream, which in turn are capable of accelerating particles. This can revive relativistic magnetized shocks as viable energization sites in astrophysical systems, such as jets and accretion disks. The generation of large-scale magnetic structures also has important implications for polarization signals from blazars.

Study on the impulse mechanism of optical films formed by laser plasma shock waves

Abstract In a high-power laser system, when the surface pressure of the optical film caused by laser plasma shock wave is greater than the adhesion per unit area of the film layer, the film will produce mechanical damage, and in serious cases, the whole system may not work. Therefore, studying the formation mechanism of optical film surface pressure and impulse caused by laser plasma shock wave is the key to ensure the normal operation of the high-power laser system. In this article, by studying the relaxation process of laser plasma shock wave on the surface pressure of optical film, and using the time accumulation effect of various pressures on the surface of the optical film, the calculation model of impulse on the optical film’s surface formed by laser plasma shock waves was established, and the variation rules of the impulse I st {I}_{\text{st}} and impulse coefficient j j on the unit area of single-layer Al2O3 and HfO2 optical films with different parameters were obtained. When the incident laser wavelength λ \lambda was 1,064 nm, the energy E E was 0.1 J 0.1\hspace{.1em}\text{J} , the pulse width t p {t}_{\text{p}} was 10 ns 10\hspace{.25em}\text{ns} , the focal length of the focusing lens f f was 350 mm 350\hspace{.25em}\text{mm} , the distance between the film surface and the focal plane of the focusing lens z 0 {z}_{0} was 5 mm 5\hspace{.5em}\text{mm} , and the film radius R R was 5 mm 5\hspace{.5em}\text{mm} , the calculation and simulation results show that the impulse I st {I}_{\text{st}} of the two films was 1 0 − 4 N s 1{0}^{-4}\hspace{.5em}\text{N}\hspace{.5em}\text{s} order of magnitude, the impulse coefficient j of the two films was 1 0 − 5 N s/J 1{0}^{-5}\hspace{.5em}\text{N}\hspace{.5em}\text{s/J} , the Al2O3 film with small atomic number will obtain larger I st {I}_{\text{st}} and j j , I st {I}_{\text{st}} and j j of the two films increase with the increase of E E and f f , and I st {I}_{\text{st}} and j j of the two films decrease with the increase of z 0 {z}_{0} and t p {t}_{\text{p}} . In the total impulse transfer time ( t 0 {t}_{0} ), I st {I}_{\text{st}} and j j both increase with the increase of R R .

Efficient Energy Conversion through Vortex Arrays in the Turbulent Magnetosheath

Turbulence is often enhanced when transmitted through a collisionless plasma shock. We investigate how the enhanced turbulent energy in the Earth's magnetosheath effectively dissipates via vortex arrays. This research topic is of great importance as it relates to particle energization at astrophysical shocks across the universe. Wave modes and intermittent coherent structures are the key candidate mechanisms for energy conversion in turbulent plasmas. Here, by comparing in-situ measurements in the Earth's magnetosheath with a theoretical model, we find the existence of vortex arrays at the transition between the downstream regions of the Earth's bow shock. Vortex arrays consist of quasi-orthogonal kinetic waves and exhibit both high volumetric filling factors and strong local energy conversion, thereby showing a greater dissipative energization than traditional waves and coherent structures. Therefore, we propose that vortex arrays are a promising mechanism for efficient energy conversion in the sheath regions downstream of astrophysical shocks.

Splinting for carpal tunnel syndrome.

Splinting for carpal tunnel syndrome.

Bubble Formation in ITER-Grade Tungsten after Exposure to Stationary D/He Plasma and ELM-like Thermal Shocks

Plasma-facing materials (PFMs) in the ITER divertor will be exposed to severe conditions, including exposure to transient heat loads from edge-localized modes (ELMs) and to plasma particles and neutrons. Tungsten is the material chosen as PFM for the ITER divertor. In previous tests, bubble formation in ITER-grade tungsten was detected when exposed to fusion relevant conditions. For this study, ITER-grade tungsten was exposed to simultaneous ELM-like transient heat loads and D/He (6%) plasma in the linear plasma device PSI-2. Bubble formation was then investigated via SEM micrographs and FIB cuts. It was found that for exposure to 100.000 laser pulses of 0.6 GWm−2 absorbed power density (Pabs), only small bubbles in the nanometer range were formed close to the surface. After increasing Pabs to 0.8 and 1.0 GWm−2, the size of the bubbles went up to about 1 µm in size and were deeper below the surface. Increasing the plasma fluence had an even larger effect, more than doubling bubble density and increasing bubble size to up to 2 µm in diameter. When using deuterium-only plasma, the samples showed no bubble formation and reduced cracking, showing such bubble formation is caused by exposure to helium plasma.