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A method for prompt estimation of a number of key parameters that determine the features of the evolution and dynamics of current sheets produced in laboratory experiments has been proposed and realized experimentally. The method is based on the analysis of time dependences of the integral plasma current during its first half-period. The transverse dimensions of the current sheets and the strength of the initial electric field that initiates the sheet formation can be estimated on the base of defining the inductances of both the entire oscillatory contour and the region where the plasma current flows. Data on the plasma conductivity can be obtained by measuring the active resistance of the plasma gap and the dimensions of the current sheet. It is shown that the conductivity increased under conditions that corresponded to an increase in plasma density, indicating a turbulent nature of the conductivity. [ABSTRACT FROM AUTHOR]

This article establishes a physical model of the interaction between a surface electron beam and the plasma with a transverse magnetic field. The dispersion relation of the beam-plasma interaction is derived by using the field matching method. The effects of magnetic field, electron beam electron density, and plasma density on the radiation frequency and z-direction wave vector are studied. The results indicate that the stronger the transverse magnetic field is, the higher is the cutoff frequency of plasma radiation. The higher the plasma density or electron beam electron density is, the higher are the corresponding radiation frequency and radiation wave number. [ABSTRACT FROM AUTHOR]

Using two separate databases of in situ ionospheric observations, we present case studies and perform a statistical investigation of the link between energetic precipitating particles during the polar night and high-latitude F-region steepening density spectra. Our study covers approximately 3 years of data obtained near the peak of the 24th solar cycle from four Defense Meteorological Satellite Program satellites and from the European Space Agency's Swarm satellites. Focusing on the midnight sector of the auroral oval, we found that there is a near-perfect co-location between high-energy precipitating particles and occurrence of dissipating F-region plasma density spectra. This is because the precipitating energy flux strongly enhances the E-region Pedersen conductivity, allowing fast and efficient dissipation of kilometer-scale F-region irregularities. Spectra that are possibly non-dissipating are in turn co-located with the distribution of soft electron precipitation. Together, dissipating and non-dissipating density spectra constitute two distinct irregularity regimes. Surprisingly, we also found that efficient dissipation notwithstanding, high-energy precipitating particles cause a net increase in the F-region irregularity power, suggesting that growth and dissipation are interlinked and that some of the observed F-region irregularities may conceivably be generated in the E region. This work is expected to be beneficial for the classification of F-region in situ density spectra and suggests that such density spectra can be used to infer the presence of high-energy or low-energy precipitations based on spectral properties. [ABSTRACT FROM AUTHOR]

The present paper deals with effect of exponential density transition on self-focusing of amplitude-modulated laser in plasma. Density of plasma changes due to the ponderomotive nonlinearity which comes into play due to non-uniform spatial profile of laser beam leading to efficient selffocusing. Propagation of amplitude-modulated laser beam is investigated and see the effect of laser intensity and exponential density ramp profile. The beam width parameter of the laser is analyzed with different laser and plasma parameters and strong self-focusing is seen for higher modulation index. [ABSTRACT FROM AUTHOR]

Earlier, a conventional grill launcher-based LHCD system has been developed to drive plasma current non-inductively in tokamaks at IPR (ADITYA and SST1) at a frequency (fo = ωo/2π) of 3.7 GHz, which has the ability to launch pure spectrum with high directivity. Grill having large number of sub-waveguides launches a sharp spectrum, which drive LH current more efficiently and therefore was preferred for carrying out plasma physics studies in a controlled manner. An over-dense plasma near the mouth of the launcher provides good coupling of LHWs with plasma and therefore the grill launcher needs to be placed close to the last close flux surface (LCFS). The grill launcher at IPR allows to launch LHWs having a parallel refractive index (N||) from 1.5 to 4.0 by varying the phase difference between adjacent sub-waveguides from 60° to 160°. For ADITYA tokamak, owing to space constraints, the grill launcher with eight sub-waveguides (arranged in two rows, each having four sub-waveguides) could be developed to launch of power up to 120 kW, and therefore, the topology of the ADITYA LHCD was not very complex. However, for the 1 MW LHCD system for SST1 tokamak, the grill launcher with sixty-four sub-waveguides (arranged in two rows, each having thirty-two sub-waveguides) was developed and the SST1 LHCD system, thus conceived, was huge and very complex offering tremendous engineering design challenges. For reactor-grade plasmas, where rf power of a few tens of MW would be launched in to the plasmas, a more compact and reactor-relevant LH launcher, often known as passive–active multijunction (PAM) is foreseen. The PAM launcher offers very good coupling with low reflection co-efficient (∼2–5%) when the plasma density near the mouth of the launcher is near cutoff densities for a given frequency (ωo = ωpe, the electron plasma frequency), and thus allowing it to be placed far away from the LCFS of the plasma, thereby minimizing deleterious effects on launcher due to hostile edge plasma conditions and makes this launcher relevant for reactor-grade plasmas. Further, the space behind the passive waveguide can be utilized for neutron shielding and efficient thermal management. On the contrary, it offers reduced directivity and the spectrum can be varied over a narrow range. Further, the network of transmission lines feeding this launcher is relatively simpler and offers less technological challenges. Thus, 250-kW PAM launcher (comprising of two modules)-based LHCD system for ADITYA-U tokamak has been designed and developed. The launched N|| may be varied over a narrow range (2.25 ± 0.375) by varying the phase difference between adjacent modules over 180° ± 90°. The physics requirements, design philosophy, engineering challenges/solutions, the key outcome and achievements as we embark on to PAM launcher are presented and discussed. Based on our experience of PAM launcher, for ADITYA-U tokamak, conceptual design of the PAM launcher for SST1 is also presented. [ABSTRACT FROM AUTHOR]

Orifice Hollow Cathodes are electric devices necessary for the functioning of common plasma thrusters for space applications. Their reliability mainly depends on the success of a spacecraft's mission equipped with electric propulsion. The development of plasma models is crucial in the evaluation of plasma properties within the cathodes that are difficult to measure due to the small dimensions. Many models, based on non-linear systems of plasma equations, have been proposed in the openiterature. These are solved commonly by means of iterative procedures. This paper investigates the possibility of solving them by means of the Particle Swarm Optimization method. The results of the validation tests confirm the expected trends for all the unknowns; the confidence bound of the discharge current as a function of mass flow rate is very narrow (2 ÷ 5) V); moreover, the results match very well the experimental data except at theowest mass flow rate (0.08 mg/s) and discharge current (1A), where the computations underpredict the discharge current to the utmost by 40%. The highest data dispersion regards the plasma density in the emitter region (±20% of the average value) and the wall temperatures (±50 K with respect to the average values) of the orifice and insert; those of the others variables are very tiny. [ABSTRACT FROM AUTHOR]

The discharge properties of post‐cathode plasma generated by grid electrode discharge were investigated. Post‐cathode plasma is the plasma, generated in an open discharge, at the other side of the cathode that is different from the electrode gap. Based on the unique electron transport, discharge chamber parameters were adjusted to compare their impact on the electron density of the post‐cathode plasma. The peak of the electron flow in the grid cathode hole and the peak of the post‐cathode plasma thickness appear in the same diameter of the grid electrode holes, which shows the crucial influence of the electron transport within the grid cathode on the post‐cathode plasma. The study also investigated the combined effects of cathode thickness and gas pressure on post‐cathode plasma thickness. The findings suggest that the primary factor influencing post‐cathode plasma thickness is the electron transport within the grid cathode. [ABSTRACT FROM AUTHOR]

The electrophysical parameters of the plasma and the kinetics of plasma-chemical processes in a CF4 + H2 + Ar mixture while varying the CF4/H2 ratio are studied. When using diagnostic methods and plasma modeling together, it is found that replacing tetrafluoromethane with hydrogen (a) leads to a decrease in the plasma density and an increase in electronegativity; and (b) it causes a disproportionately sharp drop in the concentration of fluorine atoms. The reason for the latter effect is the increase in the frequency of the death of atoms in reactions of the CHFx + F → CFx + HF type initiated by heterogeneous recombination via the CFx + H → CHFx mechanism. The simultaneous increase in the concentration of polymer-forming CHxFy (x + y < 3) radicals indicates an increase in the polymerization load of the plasma on the surfaces in contact with it. [ABSTRACT FROM AUTHOR]

This is a review on recent results on the equations of motion for light rays in a non-magnetised pressure-free plasma on a general-relativistic spacetime. Under the assumption that both the spacetime metric and the plasma density are stationary and axisymmetric, the necessary and sufficient conditions are given for the existence of a (generalised) Carter constant. It is shown how, if these conditions are satisfied, the shadows of a Kerr black hole and of a Schwarzschild black hole can be calculated in a plasma. An example is given for an axisymmetric and static plasma on the Schwarzschild spacetime where circular light rays off the equatorial plane exist. [ABSTRACT FROM AUTHOR]

At the research and production company "PlasmaScience" (Ust-Kamenogorsk, Kazakhstan), a linear plasma generator installation, KAZ-PSI (Kazakhstan Plasma Generator for Plasma Surface Interactions), has been developed and constructed for the study of the interaction of plasma and materials. This article outlines some features of the developed experimental installation designed for the investigation of surface–plasma interactions. The primary components of the linear plasma installation include an electron-beam gun with a LaB6 cathode, a plasma-beam discharge chamber, an interaction chamber, a target device, and an electromagnetic system comprising electromagnetic coils. The KAZ-PSI unit enables continuous plasma generation using hydrogen, deuterium, helium, argon, and nitrogen. The electron density of the plasma is in the range of about 1017–1018 m−3 and the electron temperature is in the range of 1 to 20 eV. The incident ion energy is regulated by applying a negative potential of up to 2 kV to the target. Experiments on the irradiation of tungsten with helium plasma were carried out using the KAZ-PSI installation for the first time. This article presents the research findings on the structure and properties of tungsten relative to the temperature of helium plasma irradiation. Alterations in roughness, microstructure, hardness, modulus of elasticity, and erosion of the tungsten's surface following helium plasma irradiation at varying temperatures were examined. The study's results indicate that helium plasma irradiation induces changes in the morphology of the tungsten's surface, creating surface relief due to sputtering by helium ions, as well as the formation of blisters. Mechanical testing revealed that after irradiation at T = 500 °C, there was an increase in hardness of up to 10%, and a slight decrease in modulus of elasticity. And after irradiation at T = 900 °C and T = 1300 °C, both hardness and elastic modulus decreased with rising temperature. The tungsten surface erosion evaluation results showed that the degrees of surface erosion increase with increasing target temperature. [ABSTRACT FROM AUTHOR]

Stimulated Raman scattering (SRS) of elliptical q-Gaussian laser beams interacting with axially inhomogeneous plasmas has been investigated theoretically. An intense laser beam with frequency ω0 propagating through plasma gets coupled with a preexisting electron plasma wave (EPW) at frequency ωep, due to ponderomotive nonlinearity on plasma electrons exerted by the laser beam. This nonlinear interaction of pump beam with EPW produces a back scattered wave at frequency ωs = ω0 − ωep. Using variational theory semi analytical solutions of the coupled nonlinear wave equations for the three waves (pump, EPW and scattered) have been obtained under W.K.B approximation technique. It has been observed that self focusing of the laser beam significantly affects the power of back scattered wave. [ABSTRACT FROM AUTHOR]

NBI-assisted plasma heating with one or two injectors of fast neutral atoms was studied at the Globus-M2 spherical tokamak at the toroidal magnetic fields of 0.8–0.9 T and plasma currents of 0.35–0.4 MA. Measurements of the spatial temperature and electron density distributions, performed using the Thomson scattering diagnostics, showed a twofold increase in heating of plasma electrons during the injection of neutral particles with energies of up to 45 keV at the beam power of 0.75 MW, as compared to the ohmic heating regime. Switching on the second additional beam with the particle energy of up to 30 keV and power of up to 0.5 MW resulted in obtaining the hot ion mode in the range of mean plasma densities of (1.6–10) × 1019 m−3. According to the data of active spectroscopy and neutral particle analyzer diagnostics, in the hot zone, the ion temperature reached 4 keV at the plasma density of 8 × 1019 m−3, which is more than 2.5 times higher than the electron temperature. [ABSTRACT FROM AUTHOR]

While Gallium Oxide (Ga 2 O 3) metal-oxide-semiconductor field-effect transistors (MOSFETs) hold great potential for high power applications, effective control of the MOS interface remains a subject of ongoing investigation. Previous studies always focused on interface traps, while overlooking the bulk and broader traps in dielectric layer. In this study, the effects of oxygen plasma treatment on the interface, border and bulk traps of Al 2 O 3 /β-Ga 2 O 3 MOS capacitors were systematically investigated through high/low frequency C–V, hysteresis C–V, and forward-bias stress tests. The results showed that devices treated with 50 W plasma power for 1 min effectively passivated the interface dangling bonds and also improved the crystalline quality of Al 2 O 3 dielectrics, exhibiting the lowest interface, border and bulk traps density. In contrast, excess plasma density or total treatment energy introduced etching defects, deteriorating the interface and dielectrics' quality. The study demonstrates that appropriate oxygen plasma pretreatment provided an effective solution for the future application of high-performance β-Ga 2 O 3 MOS devices. • The effects of oxygen plasma treatment on the interface, border and bulk traps of Al 2 O 3 /β-Ga 2 O 3 MOS capacitors were investigated. • Al 2 O 3 /β-Ga 2 O 3 MOS capacitors treated with 50 W plasma power for 1 min exhibitied the lowest interface, border and bulk traps density. • Excess plasma density or total treatment energy introduced etching defects, deteriorating the interface and dielectrics' quality. [ABSTRACT FROM AUTHOR]

• Mass flow rate and RF power have positive correlation with THz signal phase. • Electron density can be calculated using THz theoretical model. • Electron density can be measured in mixed gas plasma as well as single gas plasma. • Electron densities measured with the Langmuir probe and terahertz waves were similar. • Plasma electron density can be successfully monitored using terahertz system. In this study, an inspection method using terahertz waves was proposed for the diagnosis of electron density using inductively coupled plasma (ICP). Plasma with low and high electron density for Ar, N 2 , O 2 , and Ar mixed (with N 2 and O 2) gases was generated by varying the RF power of the ICP and mass flow rate. Based on the theoretical analysis about propagation characteristics of the THz waves in Ar, N 2 , O 2 , and Ar mixed (with N 2 and O 2) gas plasma, the electron density of the ICP was measured according to RF power and mass flow rate. These results were verified using a Langmuir probe that can measure the electron density distribution. [ABSTRACT FROM AUTHOR]

In this paper the influence of large-scale decreasing and increasing gradients of the density of magnetized plasma on the relaxation process of a continuously injected relativistic electron beam with an energy of 660 keV ( v b = 0.9 c) and a pitch-angle distribution is studied using particle-in-cell numerical simulations. It is found that for the selected parameters in the case of a smoothly decreasing gradient and in a homogeneous plasma the formation of spatially limited plasma oscillations of large amplitude occurs. In such cases, modulation instability develops and a long-wave longitudinal modulation of the ion density is formed. In addition, the large amplitude of plasma waves accelerates plasma electrons to energies on the order of the beam energy. In the case of increasing and sharply decreasing gradients, a significant decrease in the amplitude of plasma oscillations and the formation of a turbulent ion density spectrum are observed. The possibility of acceleration of beam electrons to energies more than 2 times higher than the initial energy of the beam particles is also demonstrated. This process takes place not only during beam propagation in growing plasma density, but also in homogeneous plasma due to interaction of beam particles with plasma oscillations of large amplitude. [ABSTRACT FROM AUTHOR]

One widely discussed mechanism to produce highly coherent radio emission of fast radio bursts (FRBs) is coherent emission by bunches, either via curvature radiation or inverse Compton scattering (ICS). It has been suggested that the plasma oscillation effect can significantly suppress coherent emission power by bunches. We examine this criticism in this paper. The suppression factor formalism was derived within the context of radio pulsars in which radio waves are in the low-amplitude, linear regime and cannot directly be applied to the large-amplitude, non-linear regime relevant for FRBs. Even if one applies this linear treatment, plasma suppression is not important for two physical reasons. First, for an efficient radiation mechanism, such as ICS, the required plasma density is not high so that a high-density plasma may not exist. Secondly, both bunched coherent mechanisms demand that a large global parallel electric field (E ∥) must exist in the emission region in order to continuously inject energy to the bunches to power an FRB. In order to produce typical FRB duration via coherent curvature or ICS radiation, a parallel electric field must be present to balance the acceleration and radiation back reaction. The plasma suppression factor should be modified with the existence of E ∥. We show that the correction factor for curvature radiation, f cur, increases with E ∥ and becomes 1 when E ∥ reaches the radiation-reaction-limited regime. We conclude that the plasma suppression effect can be ignored for realistic FRB emission models invoking bunched coherent radio emission. [ABSTRACT FROM AUTHOR]

The production of broadband, terawatt terahertz (THz) pulses has been demonstrated by irradiating relativistic lasers on solid targets. However, the generation of extremely powerful, narrow-band and frequency-tunable THz pulses remains a challenge. Here, we present a novel approach for such THz pulses, in which a plasma wiggler is elaborated by a table-top laser and a near-critical density plasma. In such a wiggler, the laser-accelerated electrons emit THz radiations with a period closely related to the plasma thickness. The theoretical model and numerical simulations predict that a THz pulse with a laser--THz energy conversion of over 2.0%, an ultra-strong field exceeding 80 GV/m, a divergence angle of approximately 20° and a center frequency tunable from 4.4 to 1.5 THz can be generated from a laser of 430 mJ. Furthermore, we demonstrate that this method can work across a wide range of laser and plasma parameters, offering potential for future applications with extremely powerful THz pulses. [ABSTRACT FROM AUTHOR]

Microwave preionization is a common technique used for electron-cyclotron resonance assisted plasma start-up in spherical tokamaks. The purpose of this work is to test the developed MEPhIST-0 tokamak preionization system and to study the preliminary preionization plasma. The gas discharge parameters are measured using Rogowski coils, optical spectroscopy, and Langmuir probes. A fast CCD camera is additionally used to capture the emission during the discharge. The results show that the preliminary plasma discharge is localized at a certain distance inside the vacuum chamber, which satisfies the condition for the existence of electron cyclotron resonance. The estimated plasma density and electron temperature are 5.5 × 1016 m–3 and 8 eV, respectively. [ABSTRACT FROM AUTHOR]

Laser ablation has many uses in industry, including laser drilling and thin-film deposition. However, the underpinning physics of laser ablation has not been fully elucidated. In particular, the differences in the behaviour of plasma plumes ablated from different materials, and which material properties are related to plume characteristics, require further study. This paper presents results from modelling the laser ablation of different photocatalytic materials using the 2D hydrodynamic laser ablation code POLLUX. The evolution of key parameters such as plasma density and temperature is investigated when the target material is changed from titanium to tantalum, zinc, copper, aluminium and gold. It was found that the atomic number of the material significantly affected the electron temperature and mass density of the subsequent plasma plume, with both parameters increasing with atomic number, whilst other parameters including the mass density, thermal conductivity and melting temperature did not affect the electron temperature or particle density of the plumes. These results provide insights for future laser ablation experiments where the aim is to change the target material, but keep the plume parameters as constant as possible. [ABSTRACT FROM AUTHOR]

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A novel magnetron assembly based on a combination of permanent magnet and adjustable electromagnetic coil is proposed for improved uniformity of the magnetron sputtering deposition process. The design of the magnetron sputtering system containing a rotating substrate and an off-axis arranged magnetron. A numerical framework has been developed to describe the evolution of the plasma density and distribution of sputtered particles. Specifically, the finite element method (FEM) was used to calculate the magnetic field and to model the magnetron sputtering discharge, and binary-collision Monte Carlo method was used to determine the transport of sputtered atoms to the substrate. Through parametric analyses, it was found that increasing the substrate-to-target distance, gas pressure, and coil current intensity benefits the uniform distribution of particles. The condition where the off-axis displacement of the magnetron effectively enhances uniformity. A strategy for optimizing deposition uniformity by combining adjustable current with an off-axis magnetron arrangement was proposed, which reduce the non-uniformity of film thickness by 77.6 % compared to the traditional fixed magnetic field model. • A magnetron assembly containing adjustable electromagnetic coils was proposed. • The plasma and particle distributions have been numerically studied. • The factors that affect the thickness distribution were discussed. • The film uniformity was effectively improved by an optimized strategy. [ABSTRACT FROM AUTHOR]

As the analysis of complicated reaction chemistry in bulk plasma has become more important, especially in plasma processing, quantifying radical density is now in focus. For this work, appearance potential mass spectrometry (APMS) is widely used; however, the original APMS can produce large errors depending on the fitting process, as the fitting range is not exactly defined. In this research, to reduce errors resulting from the fitting process of the original method, a new APMS approach that eliminates the fitting process is suggested. Comparing the neutral densities in He plasma between the conventional method and the new method, along with the real neutral density obtained using the ideal gas equation, confirmed that the proposed quantification approach can provide more accurate results. This research will contribute to improving the precision of plasma diagnosis and help elucidate the plasma etching process. [ABSTRACT FROM AUTHOR]

We study linear torsional Alfvén waves in a magnetic flux tube with an arbitrary cross-section. We assume that the equilibrium magnetic field is propagating in the z-direction in Cartesian coordinates x , y , and z. The tube cross-section is bounded by a smooth closed curve. Both plasma and magnetic field are homogeneous outside this curve. The magnetic field magnitude is a function of x and y, while the density is a product of two functions: one dependent on z and the other dependent on x and y. As a result, the Alfvén speed is also equal to V 0 (x , y) times a function of z. We define Alfvén waves as waves that do not disturb plasma density. We show that these waves can exist only when the magnetic field magnitude is a function of V 0 . When the condition of existence of Alfvén waves is satisfied, the waves are polarised in the directions tangent to the level lines of V 0 (x , y) and orthogonal to the equilibrium magnetic field. We found that the Alfvén wave amplitude has a specific form that depends on a particular coordinate system. [ABSTRACT FROM AUTHOR]

Recent experiments in Hybrid Illinois Device for Research and Applications (HIDRA) have had operational discharges between t discharge = 60 and 1000 s using electron cyclotron resonant heating (ECRH) of the plasma. This means that quasi-steady-state plasma discharges reach conditions to study long-pulse plasma material interactions (PMIs). The newly commissioned HIDRA-Material Analysis Test-stand PMI diagnostic is used to place a drop of lithium onto a heated tungsten surface, transfer the sample in-vacuo and expose it in a helium plasma. Helium is of interest as there is an open question to whether lithium will be able to remove helium ash in real fusion devices. The introduction of the W-Li sample in HIDRA resulted in evaporation of lithium into the helium plasma during a 600 s pulse and caused a reduction of over 90% in neutral pressure during the discharge. It was also observed that the plasma density and temperature increased by over 2.5 times. Using spectroscopy and a helium collisional radiative model, the peak temperature and density of the helium plasma can be monitored during the discharge. During lithium evaporation, as significant lithium ionization occurs, there is a 85% drop in the HIDRA vessel neutral pressure, despite a constant flow rate of He gas. This reduction in neutral pressure is supported by spectroscopy data with corresponding reductions in He I line intensities (587 nm, 667 nm, 706 nm, and 728 nm), as well as those of other impurities. At one point in the discharge a lithium plasma is created, as indicated by an increase in Li+ emission and a complete reduction in He+ emission, but the electron density jumps from n e = 3 Ă— 1018 mâˆ'3 to over n e = 8 Ă— 1018 mâˆ'3 while the core temperature stays relatively constant between T e = 16 eV and 20 eV. Once lithium has completely evaporated from the sample and the majority of the ionized lithium has diffused from the plasma to the vessel walls, pressure and spectroscopy data paired with He collisional radiative model calculations shows a re-establishment of a helium plasma in a low recycling regime. In this regime, the density drops down to n e = 2 Ă— 1018 mâˆ'3 and the electron temperature increases from T e = 20 eV to over T e = 50 eV indicating an increase in helium heating efficiency. This is also indicated by the He+ emission re-establishing and having a higher intensity. In this paper we show the results from the first lithium campaign in HIDRA. In the presence of lithium, and in particular when lithium ions are present, the helium disappears from the plasma via an as of yet unknown complex relationship that needs to be further studied. The most likely explanation is that the lithium ions are distributed around the vessel and able to trap helium to the surface turning HIDRA into a large gettering surface. These results have potential implications on future plasma facing component design using liquid lithium for impurity and recycling control using limiters and divertors. [ABSTRACT FROM AUTHOR]

As the critical dimension of transistors has become lower and the stacked layer of semiconductors has become higher, virtual diagnostics to monitor the status of plasma in an etching process has been important because of the reliability of process. In this study, we proposed the model to predict a plasma density of the etch equipment with high accuracy using OES data despite a small number of process conditions. The proposed model could improve the prediction performance of multilayer perceptron by using pre-trained variational auto-encoder as an initializer and had the best performance of several regression methods. At application point of view, it is expected that the model can be used to monitor a plasma density when a wafer is absent from the chamber. Moreover, using the proposed model can more easily understand the status of plasma rather than monitoring thousands of sensor data even without the knowledge about plasma. [ABSTRACT FROM AUTHOR]

This paper presented a zero dimensional numerical model of air and argon microwave discharge plasma and investigated the effects of the reduced electric field intensity and the duty cycle on air and argon microwave discharge plasma. The time evolution of electron density and the change of average particle density was described under different reduced electric field intensity and duty cycle. Also, the main generation paths of different particles on air reaction were also discussed. The results showed that the peak electron density of air and argon microwave discharge plasma increases with the increase of reduced electric field intensity. With the increase of duty cycle, the peak electron density of air microwave discharge plasma decreased, while the peak electron density of argon plasma remained unchanged. The average density of most particles increased with the increase of reduced electric field intensity and duty cycle, and the average electron density of argon plasma was higher than that of air. [ABSTRACT FROM AUTHOR]

Radiative recombination cross sections of oxygen ions from O+ to O6+ are calculated by an atomic model assuming central field and Hartreeâ€"Fockâ€"Slater approximation for exchange potential. The recombining ions are considered on their ground states, to form recombined ions on their ground states as well as on several subshells up to 4 d. The effect of plasma density on the cross sections is taken into account by varying the Wignerâ€"Seitz cell representing the atomic volume containing bound and free electrons. It is shown that the increase of plasma density significantly enhances the cross sections involving excited states of the recombined ions at atmospheric pressures and beyond. These cross sections may be used in collisional-radiative models for fully ionized plasma simulations in the frame work of, for example, switches in Marx generator and laser-induced plasmas in air. [ABSTRACT FROM AUTHOR]

The results of modeling of the plasma initiation and an inductive plasma current ramp up using the SCENPLINT, TRANSMAK, and DINA codes in the TRT (Tokamak with Reactor Technologies) are presented. The initial poloidal magnetic flux provided by the poloidal system, consumption of the poloidal flux for breakdown and the poloidal flux consumption for obtaining the plasma current of 5 MA within 30 s with a maximum field limit of 14 T in the central solenoid and less than 7 T in the other coils are calculated. At the beginning of the scenario, the plasma has a limiter configuration, the elongation of which increases from k ≈ 1 to k ≈ 1.5. The divertor configuration is formed by time of 13 s at the plasma current of Ip ≈ 2 MA. The plasma current ramp up to the design value Ip ≈ 5 MA is carried out simultaneously with the formation of an equilibrium configuration with k ≈ 2.0 at a gradual increase of plasma density and an increase of ECR heating power to 10 MW. [ABSTRACT FROM AUTHOR]

The plasma produced by the electrical explosion of a metal array bridge foil converges, which helps improve the energy utilization efficiency in the process of electrical explosion. Atomic emission spectrometry was carried out to conduct a spatiotemporal analysis of the plasma spectrum produced by the electrical explosion of array and single bridge foils, and the influence of the structure of the bridge foils on the spectral intensity of the plasma was analyzed. The Boltzmann multispectral slope method and the Stark broadening method were applied to obtain the evolution laws of the temperature and electron density of the plasma over time. The results show that compared with the single bridge foil, due to the convergence effect of the plasma, the spectral intensity and temperature of the plasma generated by the electrical explosion of array bridge foils are higher in the convergent zone, while the electron density is lower. [ABSTRACT FROM AUTHOR]