Plasma Interaction Studies Research Articles

Post-plasma catalysis: charge effect on product selectivity in conversion of methane and nitrogen plasma to ethylene and ammonia

A combined experimental and theoretical study of the post-microwave plasma interaction with catalytic surfaces to enhance the ethylene and ammonia production from methane and nitrogen conversion.

Probe Device for Comprehensive Study of Plasma Interaction with Divertor for TRT Tokamak

Probe Device for Comprehensive Study of Plasma Interaction with Divertor for TRT Tokamak

Study of Plasma Interaction with Liquid Lithium Multichannel Capillary Porous Systems in SCU-PSI

In this paper, an embedded multichannel capillary porous system (EM-CPS) was designed and fabricated with 304 stainless steel using the laser ablation method. The EM-CPS revealed its excellent ability to wick liquid lithium to its surface effectively. The interaction between Li-prefilled EM-CPS and plasma was studied, and the results showed that the surface temperature decreased by ~140 °C compared with the results of the experiment of EM-CPS without lithium filling. Additionally, EM-CPS displayed a better heat transfer performance and stronger radiation loss of the vapor cloud than the traditional woven tungsten-based meshes. In addition, the drift of the lithium vapor cloud center was found during plasma irradiation and led to a decrease in the intensity of the Li 670.78 nm emission line detected by the spectrometer at the observation point. When the thermal load deposited on the sample surface is reinforced by increasing the magnetic field, the rise in surface temperature is restrained due to the enhanced heat dissipation capability of lithium. SEM images of irradiated samples showed that the 304 stainless steel-based EM-CPS has corrosion problems due to the interaction between liquid lithium and argon plasma, but it still showed good plasma-facing characteristics. These findings provide a reference for further studies of embedded multichannel CPSs with plasma-facing components (PFCs) in linear plasma devices and tokamaks in the future.

Multi‐Fluid MHD Simulations of Europa's Plasma Interaction Under Different Magnetospheric Conditions

AbstractEuropa hosts a periodically changing plasma interaction driven by the variations of Jupiter's magnetic field and magnetospheric plasma. We have developed a multi‐fluid magnetohydrodynamic (MHD) model for Europa to characterize the global configuration of the plasma interaction with the moon and its tenuous atmosphere. The model solves the multi‐fluid MHD equations for electrons and three ion fluids (Jupiter's magnetospheric O+, as well as O+ and O2+ originating from Europa's atmosphere) while incorporating sources and losses in the MHD equations due to electron impact and photo‐ionization, charge exchange, recombination and other relevant collisional effects. Using input parameters constrained by the Galileo magnetic field and plasma observations, we first demonstrate the accuracy of our model by simulating the Galileo E4 and E14 flybys, which took place under different upstream conditions and sampled different regions of Europa's interaction. Our model produces 3D magnetic field and plasma bulk parameters that agree with and provide context for the flyby observations. We next present the results of a parameter study of Europa's plasma interaction at three different excursions from Jupiter's central plasma sheet, for three different global magnetospheric states, comprising nine steady‐state simulations. By separately tracking multiple ion fluids, our MHD model allows us to quantify the access of the Jovian magnetospheric plasma to Europa's surface and determine how that access is affected by changing magnetospheric conditions. We find that the thermal magnetospheric O+ precipitation rate ranges from (1.8–26) × 1024 ions/s, and that the precipitation rate increases with the density of the ambient magnetospheric plasma.

Characterization of residual inhomogeneities in a plasma created by laser ionization of a low-density foam

Low density foams are widely used for laser plasma interaction studies. Here, we present the results of first direct measurements of a residual level of inhomogeneity of a foam plasma by using a pump-probe technique. It is demonstrated that large scale density modulations in such a plasma can survive a time larger than 1 ns, much longer than the plasma formation time.

The nonlinear wave in semiconductor quantum plasma for laser beam in a self-consistent plasma channel

In this paper investigating the current task, our emphasis is on distributed a serious laser beam in a self-made plasma channel. As the intensity of the laser beam increases, the medium displays the neuromuscular electrical conductivity functioning as a result of the mass effectiveness of the effectiveness of the electrons as well as the intensity of the electrons. Based on Wentzel–Kramers–Brillouin and paraxial ray theory, the steady-state solution of an intense, Gaussian electromagnetic beam is studied. The differential equation of the distance with the beam width parameter is derived, including the relativistic effects of self-focusing (SF) and self-channeling ponder motive. Plasma propagation is a radial dynamical force, depending on the width of the beams and σp greater, plasma ratio frequency screws. Once the distribution regimes, the beam power beamwidth is obtained in plane. The σp is a particular value characterized by standard deviation, oscillation and diffusion regimes such as self focusing. The corresponding center parameters are intended for introduction of the plasma density curve and the laser beam is spatially analyzed to the spatial plasma. Performing this margin can lead to a long distance laser beam guide. The disadvantage of numerical predictions is done for laser plasma interaction studies for common factors.

Modern Diagnostics for Investigation of Lithium Element Behavior in Tokamaks

The introduction of lithium as a material for production of in-vessel plasma-facing elements of the tokamak necessitates the development of the corresponding diagnostic instruments. A series of diagnostic devices have been developed and fabricated for tokamaks T-10 and T-11 M which make it possible to investigate the processes of lithium transport in the tokamak plasma scrape-off layer (SOL), real-time dynamics of lithium deposition at various temperatures of a collecting surface by means of the microbalance technique, adsorption/desorption process of hydrogen isotopes on the lithium surface, and influence of an electric field on lithium trapping. Scanning of plasma parameters is provided by Langmuir probes. Such devices can be used to extract the lithium deposited on the inner walls of the tokamak vacuum chamber without opening it. For these purposes, a lock chamber and bellows-free vacuum input allowing movement and rotation is provided. It is planned to perform the study of the tokamak plasma interaction with in-vessel lithium-based elements by means of infrared (IR) thermometry. It is planned to try out this technique on the Т-11М tokamak using a special device based on a IR camera.

Experience on divertor fuel retention after two ITER-Like Wall campaigns

The JET ITER-Like Wall experiment, with its all-metal plasma-facing components, provides a unique environment for plasma and plasma-wall interaction studies. These studies are of great importance in understanding the underlying phenomena taking place during the operation of a future fusion reactor. Present work summarizes and reports the plasma fuel retention in the divertor resulting from the two first experimental campaigns with the ITER-Like Wall. The deposition pattern in the divertor after the second campaign shows same trend as was observed after the first campaign: highest deposition of 10–15 μm was found on the top part of the inner divertor. Due to the change in plasma magnetic configurations from the first to the second campaign, and the resulted strike point locations, an increase of deposition was observed on the base of the divertor. The deuterium retention was found to be affected by the hydrogen plasma experiments done at the end of second experimental campaign.

Abstract P4-01-08: Specific detection of anti-Her2 PEGylated PrecisionMRX® nanoparticles measured using superparamagnetic relaxometry

Abstract Current methods for detecting solid tumors lack sensitivity and diagnose primary and metastatic lesions only after the tumor is well established. Superparamagnetic Relaxometry (SPMR) is a combination technology that utilizes superconducting quantum interference detectors (SQUID) to measure the magnetization of superparamagnetic, tumor-targeting magnetite (Fe3O4) nanoparticles. Conceptually, PEGylated Fe3O4 nanoparticles labeled with a tumor targeting moiety (i.e., a monoclonal antibody) are intravenously injected and specifically target solid tumors utilizing both passive (the EPR effect) and active (receptor-mediated) mechanisms. Subsequently, the Fe3O4 nanoparticles are magnetized by a low field magnetic pulse in the MRX™ instrument and only those particles that are bound to their target site are measured by the SQUID sensors. Unbound nanoparticles are not detected. To demonstrate the utility of SPMR in detecting cancer we used PEGylated PrecisionMRX® nanoparticles that are covalently linked with a monoclonal antibody (mAb) targeting ERB-2 (anti-Her2). The particles were characterized for size (by dynamic light scattering), free and bound mAb (by ELISA), antibody potency (by bioassay) and stealth (in plasma interaction studies). In vitro, the anti-Her2 conjugated particles exhibited specific binding to ERB-2 overexpressing breast cancer cells (MCF-7/Her2-18). Specific binding was defined by the ability of the native mAb to competitively block the binding of the anti-HER-2 conjugated particles to ERB-2 antigen coated on ELISA plates or expressed on the cell surface. In addition, in ERB-2 negative cell lines, the anti-Her2 conjugated particles exhibited little to no binding. In vivo, anti-Her2 conjugated PrecisionMRX exhibited significantly longer circulation times when compared to unPEGylated particles. Distinct magnetic dipoles were detected by the MRX instrument at the target site (the tumor) and site of nanoparticle elimination (the liver). These data were confirmed in excised organs showing significant magnetic moments in the liver, tumor, and spleen. Analysis of the MRX SPMR data suggest that the technology can detect as few as 10,000 cancer cells in vivo by optimizing the nanoparticles for stealth and targeting. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. Citation Format: Weldon CL, Minser KE, Gomez A, Anderson WH, Karaulanov T, Hathaway HJ, Huber DL, Vreeland EC, Paciotti G. Specific detection of anti-Her2 PEGylated PrecisionMRX® nanoparticles measured using superparamagnetic relaxometry [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-01-08.

Detailed calibration of the PI-LCX:1300 high performance single photon counting hard x-ray CCD camera**Project supported by the Science Foundation of China Academy of Engineering Physics (Grant Nos. 2013A0103003 and 2012B0102008) and the National High-Tech Inertial Confinement Fusion Committee of China.

X-ray charge-coupled-device (CCD) camera working in single photon counting mode is a type of x-ray spectrometer with high-sensitivity and superior signal-to-noise performance. In this study, two single photon counting CCD cameras with the same mode (model: PI-LCX: 1300) are calibrated with quasi-monochromatic x-rays from radioactive sources and a conventional x-ray tube. The details of the CCD response to x-rays are analyzed by using a computer program of multi-pixel analyzing and event-distinguishing capability. The detection efficiency, energy resolution, fraction of multi-pixel events each as a function of x-ray energy, and consistence of two CCD cameras are obtained. The calibrated detection efficiency is consistent with the detection efficiency from Monte Carlo calculations with XOP program. When the multi-pixel event analysis is applied, the CCDs may be used to measure x-rays up to 60 keV with good energy resolution (E/ΔE ≈ 100 at 60 keV). The difference in detection efficiency between two CCD cameras is small (5.6% at 5.89 keV), but the difference in fraction of the single pixel event between them is much larger (25% at 8.04 keV). The obtained small relative error of detection efficiency (2.4% at 5.89 keV) makes the high accurate measurement of x-ray yield possible in the laser plasma interaction studies. Based on the discrete calibration results, the calculated detection efficiency with XOP can be used for the whole range of 5 keV–30 keV.

Development of fast video recording of plasma interaction with a lithium limiter on T-11M tokamak

A new high-speed color camera with interference filters was installed for fast video recording of plasma-surface interaction with а Lithium limiter on the base of capillary-porous system (CPS) in T-11M tokamak vessel. The paper presents the results of the study of tokamak plasma interaction (frame exposure time up to 4μs) with CPS Lithium limiter in a stable stationary phase, unstable regimes with internal disruption and results of processing of the image of the light emission around the probe, i.e. e-folding length for neutral Lithium penetration and e-folding length for Lithium ion flux in SOL region.

Studies of plasma interactions with tungsten targets in PF-1000U facility

Abstract This paper presents results of experimental studies of tungsten samples of 99.95% purity, which were irradiated by intense plasma-ion streams. The behaviour of tungsten, and particularly its structural change induced by high plasma loads, is of great importance for fusion technology. The reported measurements were performed within a modified PF-1000U plasma-focus facility operated at the IFPiLM in Warsaw, Poland. The working gas was pure deuterium. In order to determine the main plasma parameters and to study the behaviour of impurities at different instants of the plasma discharge, the optical emission spectroscopy was used. The dependence of plasma parameters on the initial charging voltage (16, 19 and 21 kV) was studied. Detailed optical measurements were performed during interactions of a plasma stream with the tungsten samples placed at the z-axis of the facility, at a distance of 6 cm from the electrode outlets. The recorded spectra showed distinct WI and WII spectral lines. Investigation of a target surface morphology, after its irradiation by intense plasma streams, was performed by means of an optical microscope. The observations revealed that some amounts of the electrodes material (mainly copper) were deposited upon the irradiated sample surface. In all the cases, melted zones were observed upon the irradiated target surface, and in experiments performed at the highest charging voltage there were formed some cracks.

Distribution regimes of intense laser beam in a self-consistent plasma channel

In the present work, we investigate the distributed regimes of an intense laser beam in a self-consistent plasma channel. As the intensity of the laser beam increases, the relativistic mass effect as well as the ponderomotive expulsion of electrons modifies the dielectric function of the medium due to which the medium exhibits nonlinearity. Based on Wentzel–Kramers–Brillouin and paraxial ray theory, the steady-state solution of an intense, Gaussian electromagnetic beam is studied. A differential equation of the beamwidth parameter with the distance of propagation is derived, including the effects of relativistic self-focusing (SF) and ponderomotive self-channeling. The nature of propagation and radial dynamics of the beam in plasma depend on the power, width of the beam, and Ωp, the ratio of plasma to wave frequency. For a given value of Ωp (<1), the distribution regimes have been obtained in beampower–beamwidth plane, characterizing the regimes of propagation as steady divergence, oscillatory divergence, and SF. The related focusing parameters are optimized introducing plasma density ramp function, and spot size of the laser beam is analyzed for inhomogeneous plasma. This results in overcoming the diffraction and guiding the laser beam over long distance. Numerical computations are performed for typical parameters of relativistic laser–plasma interaction studies.

A new 3-D spherical hybrid model for solar wind interaction studies

[1] A 3-D spherical hybrid model has been developed to study how the solar wind interacts with various solar system bodies. The main advantages of the new spherical model, called the HYB-s, compared with traditional Cartesian models are that the spherical model allows significantly reduced radial cell size and, consequently, a smaller total number of cells and particles in the simulation. The high radial resolution makes it possible to use the new model for 3-D physical studies that have not been feasible before. Especially, the spherical model allows the inclusion of self-consistent ionospheric photochemistry in global hybrid simulations of the solar wind interaction with terrestrial planets Venus and Mars. In this paper we describe the main aspects of the developed spherical hybrid model. We also study the solar wind interaction with Venus in a global hybrid simulation using the spherical hybrid model and our already published Cartesian hybrid model. The comparison between the two models suggests the high potential of the developed spherical hybrid model in studies of planetary plasma interactions.

Laser–plasma interaction studies in the context of shock ignition: the regime dominated by parametric instabilities

The shock ignition concept for inertial confinement fusion includes launching a strong shock with a high-intensity laser spike into an imploding shell. The laser intensity in the plasma corona is above the threshold for parametric instabilities, thus providing conditions for strong non-linear effects. Here we present a series of one-dimensional kinetic simulations of laser–plasma interactions in such a regime. After a transient period of strong non-stationary scattering, the laser–plasma interaction enters an asymptotic regime where a significant part of the incident laser flux is absorbed in the plasma and is transformed into hot electrons. The repartition of the absorbed energy and spectral characteristics of the scattered radiation are presented for laser intensities in the range 2.4–24 PW cm−2. For a laser intensity of 8 PW cm−2, the total absorption is 69% ; about 50% of absorption takes place at quarter critical density and the remaining 19% at 1/16th of the critical density. 52% of the total laser pulse energy are absorbed due to stimulated Raman scattering, which produces electrons with a temperature of about 30 keV, and 17% is absorbed due to cavitation, which produces a more isotropic distribution of hot electrons with a temperature of about 10 keV.

Guest Editorial Special Issue on Dusty Plasmas

This special issue contains papers solicited at the 13th Workshop on the Physics of Dusty Plasmas held May 20-23 in Waco, TX, USA and follows the tradition of earlier workshops, which resulted in such issues in 1994, 2001, 2004, 2007, and 2010. Dusty plasmas constitute a fully developed interdisciplinary field with direct connections to astrophysics, nanoscience, fluid mechanics, and material science as defined through experimental, theoretical, and numerical studies. The field achieved an interdisciplinary research focus when the 1986 fly by of Halley's Comet and Voyager's images of Saturn's rings focused the attention of plasma physicists on a field that had previously been considered as purely planetary science. Joint efforts between these disciplines quickly led to rapid advancement in both plasma physics (e.g., discovery of dustacoustic waves, dust-ion-acoustic waves) and the planetary sciences (e.g., spokes in Saturn's rings, Jovian stream particles). The primary objectives of the 13th Workshop on the Physics of Dusty Plasmas were to provide a review of recent advancements in the field of complex plasma, define new/existing/outstanding issues and research challenges, and strengthen engagement between the field of complex plasma and other research related disciplines. Researchers from universities all over the world, including twenty-six graduate students evenly split between universities in the United States and international universities, participated in the workshop. Eighty-six paper and poster presentations were accepted covering topics including laboratory, theoretical, and computational studies of dust plasma interactions. Sixteen papers from the Waco meeting appear in this special issue covering topics across a variety of theoretical and experimental areas. Instabilities in dusty plasma systems, the manner in which such instabilities are believed to be linked to the onset of dust density or dust-acoustic waves and the mechanism by which these waves evolve and are related to the ambient plasma are reported. Dust dynamics, mass loss, and a method for employing the plasma glow to probe the plasma sheath in the vertical direction are discussed. A numerical method allowing calculation of the grain charge while including secondary electron emission and the application of this method to the lunar environment is provided. Finally techniques for stereoscopic observations, three-dimensional models of dust plasma interactions and dusty plasma experiments allowing inspection of magnetized dusty plasmas and dusty plasma environments containing chemically reactive gases are reported.

Comparison of different approaches to the numerical calculation of the LMJ focal

The beam smoothing in the focal plane of high power lasers is of particular importance to laser- plasma interaction studies in order to minimize plasma parametric and hydrodynamic instabilities on the target. Here we investigate the focal spot structure in different geometrical configurations where standard paraxial hypotheses are no longer verified. We present numerical studies in the cases of single flat top square beam, LMJ quadruplet and complete ring of quads with large azimuth angle. Different calculations are made with Fresnel diffraction propagation model in the paraxial approximation and full vector Maxwell's equations. The first model is based on Fourier transform from near to far field method. The second model uses first spherical wave decomposition in plane waves with Fourier transform and propagates them to the focal spot. These two different approaches are compared with Miro (1) modeling results using paraxial or Feit and Fleck options. The methods presented here are generic for focal spot calculations. They can be used for other complex geometric configurations and various smoothing techniques. The results will be used as boundary conditions in plasma interaction computations. where f(x,y) is the amplitude of the field with a spatial extension size of a and k0 = /c is the wave number of the field. The field expression in the k space (spatial frequencies) with one fast Fourier transform (FFT) requires a large number of points. But for a parabolic phase lens, plane wave decomposition of the electric field in the k space with double FFT allow to reduce the spatial sampling (2048 points instead of 256000 for a = 1.2m and zf = 0.8m). The plane wave decomposition with two FFT is given by:

Perpendicular flow deviation in a magnetized counter-streaming plasma

Charged dust exists in various regions in the Solar System. How this charged dust interacts with the surrounding plasma is not well understood. In this study we neglect the charging process and treat the charged dust as a fluid interacting with the ambient magnetized plasma fluid. The model reproduces the expected plasma deceleration with both positively charged and negatively charged dust, but a new effect arises. Negatively charged dust causes the magnetic field to bend in the direction of the convection electric field, while positively charged dust causes the opposite magnetic field bending. Consequently, the interaction does not only result in a perpendicular shift in the downstream current system, but also a rotation in these currents. We present quantitative results using the multi-fluid MHD code BATSRUS for both subsonic and supersonic interactions. We find that the same perpendicular bending exists for all counter-streaming interaction problems, independent of the shape of the dust cloud. The new model can be applied to plasma interaction studies including, but not limited to, charged dust particles in the solar wind, cometary plasma, the Enceladus plume, and active plasma releases, such as the Active Magnetospheric Particle Tracer Experiment (AMPTE) mission. The predicted behavior is consistent with observations at Enceladus.

Laser plasma interaction studies in the context of shock ignition—Transition from collisional to collisionless absorption

The shock ignition concept implies laser pulse intensities higher than 1015 W/cm2 (at the wavelength of 351 nm), which is the commonly accepted limit where the inverse bremsstruhlung absorption dominates. The transition from collisional to collisionless absorption in laser plasma interactions at higher intensities is studied in the present paper with the help of large scale one-dimensional particle-in-cell simulations. The initial parameters are defined by the hydrodynamic simulations corresponding to recent experiments. The simulations predict that a quasi-steady regime of laser plasma interaction is attained where the total laser energy absorption stays on the level of ∼65% in the laser intensity range 1015–1016 W/cm2. However, the relation between the collisional and collisionless processes changes significantly. This is manifested in the energy spectrum of electrons transporting the absorbed laser energy and in the spectrum of the reflected laser light.

A.I.K.E.F.: Adaptive hybrid model for space plasma simulations

The interaction between magnetized space plasmas and obstacles like comets, asteroids or planets is determined by a variety of physical processes that occur simultaneously on significantly different length and time scales. Frequently the dynamics of individual ions play a key role for the shape of the interaction region: strong velocity shear between light and heavy plasma constituents, non-Maxwellian particle distributions due to pick up and asymmetries in the magnetic field topology are crucial in determining this type of interaction. Covering these processes is beyond the scope of any Magnetohydrodynamic (MHD) model. In order to account for these effects we have developed a new adaptive hybrid code A.I.K.E.F. ( Adaptive Ion- Kinetic Electron- Fluid). The code operates on Cartesian meshes that can adapt to the physical structures in both, space and time. To the authors' knowledge, there is no other adaptive hybrid simulation code in space plasma physics to the present day. Adaptivity is implemented by means of Hybrid-Block-AMR, that is individual octs are refined rather than entire blocks, where an oct is one eighth of a block. In order to account for a reasonable number of particles in each cell, particles are refined via splitting and merging. Both procedures conserve mass, momentum and kinetic energy. The code is implemented in C++ and efficiently parallelized for distributed systems by means of the Message Passing Interface (MPI). In order to demonstrate the validity of our newly developed code we have applied it to a series of fundamental test scenarios. On the one hand we demonstrate that the dispersion relation as well as the propagation characteristics of MHD and whistler mode waves are quantitatively reproduced by our simulation code. Wave propagation remains unaffected when traveling through regions that include different refinement levels. On the other hand we verify that the results obtained on high resolution uniform meshes are identical to the results from adaptive simulations that use coarse base meshes but include various levels of refinement. A remarkable speedup could be observed: the adaptive simulations required 71 times less CPU-hours than the uniform mesh simulations. Finally, we present a first series of global, three-dimensional simulations for the interaction of Mercury with the solar wind and a real time study of Titan's plasma interaction during a magnetosheath excursion.