Values Of Electron Temperature Research Articles

Influence of Magnetic Mirror on the Emission Spectra of DBD Actuator

The research investigated the effect of magnetic mirror configuration on the properties of plasma formed in a dielectric barrier discharge (DBD) actuator under atmospheric pressure. The discharge was formed when a high alternating voltage of 22 kV at a frequency of 9 kHz was applied between the electrodes under atmospheric pressure. The magnetic mirror was created when two permanent magnets were placed behind the electrodes. Plasma emission spectra were detected using a photoemission spectrometer at different horizontal distances (D) between the dielectric and the actuator, ranging from 0 to 5 cm. The effect of the magnetic mirror on the plasma properties at different horizontal distances was studied. The results indicated that the value of electron temperature increases with an increase in the horizontal distance at a smaller rate in the presence of the magnetic mirror configuration. The decrease in the surface area of the electrode led to a significant increase in the electron number density in the presence of the magnetic field. The magnetic mirror affected the value of all the plasma properties studied. At the same time, there was no effect on the behaviour of plasma properties in the presence of magnetic mirror configurations.

Electron cyclotron current start-up using a retarding electric field in the QUEST spherical tokamak

Abstract The plasma current start-up experiment is conducted through electron cyclotron (EC) heating in the QUEST spherical tokamak. During the EC heating, the application of a toroidal electric field in the opposite direction to the plasma current effectively inhibits the growth of energetic electrons. Observations show rapid increases in plasma current and hard x-ray count immediately following the cancellation of the retarding electric field. When a compact tokamak configuration maintains equilibrium on the high field side, along with the retarding field, it leads to effective bulk electron heating. This heating achieved an electron temperature of T e ≈ 1 keV at electron density n e > 1.0 × 1018 m−3. Ray tracing of the EC wave verifies that more power absorption into plasma through a single-pass occurs around the second resonance layer with higher values of electron density and temperature.

Electron cyclotron emission calibration with Thomson scattering using a wide scan of toroidal magnetic field of KSTAR.

The Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak is capable of operating at a wide range of toroidal magnetic fields up to 3.5T at the major radius. The electron cyclotron emission (ECE) diagnostic on KSTAR is required to cover a broad frequency range for electron temperature profile measurements in both the low and high field sides. To meet these broadband requirements, the ECE system consists of W-band (78-110GHz) and D-band (110-162GHz) heterodyne radiometers. The two radiometers are connected to 28 and 48 detection channels, respectively. However, since the absolute ECE calibration based on the hot-cold calibration has been very challenging, an alternative method of calibration was performed using Thomson scattering measurements and varying toroidal magnetic fields. As the toroidal magnetic field is scanned from 1.6 to 3.2T in steps of 0.2T, most of the 76 ECE channels are calibrated relatively by the electron temperature values of Thomson scattering in a narrow region (0.2 < r/a <0.6). In this article, the methodological details of the ECE calibration are described. In addition, to demonstrate the robustness of the ECE calibration factors, the calibrated electron temperature profiles from ECE measurements are compared with the ion temperature profiles in terms of the plasma position as the plasma positon shifts outward.

Time-resolved analysis of Ar metastable and electron populations in low-pressure misty plasma processes using optical emission spectroscopy

Misty plasmas have recently emerged as a promising tool for nanocomposite thin films deposition. However, aerosol-plasma interactions remain poorly documented, especially at low working pressure. In this work, optical emission spectroscopy is used to probe the temporal evolution of three fundamental plasma parameters during pulsed liquid injection in an inductively coupled argon plasma at low-pressure. Time-resolved values of metastable argon density, electron temperature, and electron density are determined from radiation trapping analysis and particle balance equations of selected argon 1s and 2p levels. Pulsed liquid injection is found to induce a sudden drop in metastable density and electron temperature, and an increase in electron density. These results are attributed to the lower ionization thresholds of the injected molecular species compared to the one of argon. In addition, upstream liquid temperature is found to affect the transitory kinetics for non-volatile solvents more than volatile ones, in accordance with a previously reported flash boiling atomization mechanism.

Empirical calibration for helium abundance determinations in active galactic nuclei

ABSTRACT For the first time, a calibration between the He i$\lambda 5876$/H $\beta$ emission line ratio and the helium abundance y = 12 + log(He/H) for Narrow line regions of Seyfert 2 Active Galactic Nuclei is proposed. In this context, observational data (taken from the SDSS-DR15 and from the literature) and direct abundance estimates (via the $T_{\rm e}$-method) for a sample of 65 local ($z \: \lt \: 0.2$) Seyfert 2 nuclei are considered. The resulting calibration estimates the y abundance with an average uncertainty of 0.02 dex. Applying our calibration to spectroscopic data containing only strong emission lines, it yields a helium abundance distribution similar to that obtained via the $T_{\rm e}$-method. Some cautions must be considered to apply our calibration for Seyfert 2 nuclei with high values of electron temperature (${\gtrsim} 20\, 000$ K) or ionization parameter ($\log U \ \gt\ {-}2.0$).

Higher order contribution to ion-acoustic Korteweg–de Vries (KdV) soliton in unmagnetized quantum plasmas with arbitrary degeneracy of electrons

The propagation of nonlinear ion-acoustic Korteweg–de Vries (KdV) solitons and dressed solitons (with higher order contribution term) in unmagnetized quantum plasmas with arbitrary degeneracy of electrons is investigated using quantum hydrodynamic model. The reductive perturbation method is used to derive the first order nonlinear ion-acoustic KdV equation and also higher order contribution of inhomogeneous differential equation is obtained for the dressed ion-acoustic wave soliton in arbitrary degenerate electron plasmas. Moreover, the higher order inhomogeneous differential equation is solved (nonsecular solution is obtained) using the renormalization method. The conditions for the validity of the higher order correction are also discussed in detail for ion-acoustic solitons in unmagnetized arbitrary degenerate electrons plasma case. The effects of chosen values of electron temperature, equilibrium fugacity and corresponding electron density of a physical quantum plasma system and quantum diffraction parameter H (for two conditions i.e., H < 2 or H > 2) on the amplitude and width of the KdV and dressed ion-acoustic wave solitons for both electrostatic potential hump (compressive) or dip (rarefactive) structures are investigated. The numerical plots are also presented for illustration with numerical values of a physical partially degenerate electrons plasma system exist in the astrophysical or laboratory conditions.

On the distribution function of electron spectra from hot laser plasmas

The emission of electrons from hot plasmas generated in the interaction of ultra-short (and ultra-high intensity) laser pulses with matter is often characterized by the so-called ‘hot electron temperature’. In this article it is shown that this number is not unambiguous. The reason is the following: to assign a temperature to an electron spectrum, it is necessary to describe the spectrum with a distribution function. However, different types of distribution functions are in use, e.g. the Boltzmann or Maxwell distribution, leading to different electron temperatures in spite of providing nearly the same form of the electron spectrum. For this reason, the main characteristics of all these distribution functions are presented in this article and compared. Depending on the distribution function used, the value of the hot electron temperature varies by up to 30% and in extreme cases by more than a factor of four. This fact should always be kept in mind when comparing values of hot electron temperatures. In addition, the reasons for using equilibrium distributions to describe the characteristics of laser-produced electrons—although probably no thermodynamic equilibrium is prevailing—are discussed.

Influence of pulse laser energy on the Nickel plasma characteristics that produced in laser-induced plasma system

تُستخدم تقنية قياس طيف الانبعاث البصري ( OES) لتحليل البلازما المتولدة من هدف (النيكل) المضاء باستخدام ليزر Q- Switched (Nd: YAG) بطاقات مختلفة في الهواء. تم استخدام طريقة التوسيع Boltzmann-Plot و Stark لحساب معاملات البلازما بما في ذلك كثافة الإلكترون (ne) ودرجة حرارة الإلكترون (Te) وتردد البلازما (fp) وطول ديباي (λD). يتضح أن قيم (ne) و (Te) و (λD) و (fp) تزداد بزيادة طاقة الليزر مع قيم درجة حرارة الإلكترون المحسوبة التي تتراوح بين (0.934 - 1.479) الكترون - فولت.

Solar Wind Density and Core Temperature Derived from the PSP Quasi-thermal Noise Measurements

Quasi-thermal noise (QTN) spectroscopy is a valuable method to deduce important parameters in space plasma, such as plasma density and temperature, especially when direct particle measurements are not available. The present study develops a new fitting method to fit the QTN spectra observed by the Parker Solar Probe (PSP) with a comprehensive theoretical QTN spectral model. By combining the steepest descent and Levenberg–Marquardt algorithms, the new method is more flexible with initial guess values but still yields reliable solar wind electron density and temperature values. The new method is applied to derive the solar wind density and core temperature from the QTN measurements during 10 encounters of PSP. The electron density and temperature values obtained vary with the radial distance from the Sun as n e ∝ r −2.12 and T e ∝ r −0.71, both of which are consistent with existing models and previous results.

Detection of Silica in Rice Husks Using Laser-Induced Plasma and Studying the Effect of Laser Energy on the Parameters of the Produced Plasma

This study aims to analyze the spectral properties of plasma produced from rice husk(Rh) using the laser breakdown spectroscopy (LIBS) method. The plasma generation process used the fundamental harmonic (1064 nm) of a Q-switched Nd:YAG laser. Yttrium aluminum garnet (YAG) is a man-made crystalline material. The laser fired pulses with a duration of 10 ns and a repetition rate of 6 Hz. Thus, the energy outputs achieved were 50–200 mJ at the wavelength of 1064 (nm). The silica content in the rice hulls was verified using an XRF measurement, which revealed the presence of silica in the rice hulls in a high percentage. Precise beam focusing was achieved by focusing the laser on the target material. This target material is placed within an atmospheric environment at standard pressure settings. The electron temperature was derived using the Boltzmann diagram method by harnessing experimental data for the linear properties associated with the neutral lines (Si II), (O II), and ion lines (Si I). The use of analytical methodology led to the determination of electron temperature values from 0.79 eV to 1.16 eV for the fundamental harmonic of the laser. At the same time, the electron (ne) density was determined by analyzing the Stark broadening profile associated with the neutral silica line. Furthermore, the study included an additional dimension by determining the plasma properties (electron temperature and electron density) by adjusting the laser energy on the target surface longitudinally along the path of the plasma plume.

Tangential extreme ultraviolet and soft x-ray diagnostic system for time-resolved temperature measurement on the High Beta Tokamak-Extended Pulse.

The High Beta Tokamak-Extended Pulse has recently incorporated a tangential multi-energy extreme ultraviolet and soft x-ray diagnostic system. This system enables measurements of the electron temperature and the examination of mode dynamics within the tokamak. While other systems have been built for poloidal views over similar temperature ranges, this is the first multi-energy tangential-view system designed to work in a temperature range below 200eV in a tokamak. To facilitate these measurements, a filter wheel comprising five distinct groups of dual-filters has been developed and implemented. By employing a combination of 0.1μm aluminum and 0.2μm titanium filters, the system allows estimation of electron temperature profiles through reconstruction of the emission profile using the standard "double-foil" technique. The influence of impurities and filter oxide layers on measurement outcomes is examined. Results reveal that, while the absolute electron temperature values may exhibit some deviations, key characteristics like the electron temperature profile shape and inversion radius during sawtooth events remain consistent. This consistency confirms the system's suitability for core plasma studies. This system has proven effective in detecting and analyzing internal magnetohydrodynamic phenomena, such as sawteeth.

Modeling of carbon nanoparticle synthesis using arc discharge method in variation through electrode’s shape and gap

Modeling of carbon nanoparticle synthesis using the arc discharge method was created by simulation. In this research, the electrode shapes and gaps between them are varied. The electrode’s shape was modeled as pointy, blunt, and square, while the electrode’s gap was modeled as modified at 0.23 mm, 0.38 mm, and 0.57 mm. This research aims to analyze forms of distribution and generated nanoparticles by demonstrating how the difference in electrode design obtains the maximum value of electron density, electron temperature, and electric potential since the discharge process. The simulation results show that the variation in shape and gap between the electrodes affects the maximum value obtained.

Spectroscopic Diagnosis of Cobalt Plasma Produced by OES Technique and Influence of Applied Voltage on Plasma Parameters

In this work, plasma system that operates at vacuum was designed and built using a sheet of cobalt metal for the purpose of diagnosing plasma and measuring its parameters, as it is very important to know the processes that accompany plasma generation and are closely related to them, including the electron density in the plasma and its temperature. The spectroscopic diagnosis was done by optical emission spectroscopy (OES) which relies on the calculation of the optical radiation emitted by the plasma to describe plasma parameters in the chemical, molecular, and ionic radiator's near environment, and applied to cobalt metal at vacuum D.C high voltage power supply. The results showed the rise of spectral lines intensity with increasing the applied voltage. The maximum peak of argon gas (ArI) was at the wavelength (811.5311) nm and the maximum peak of cobalt metal (CoI) was at the wavelength of 242 nm, where argon gas was used at the fifth flow per minute with variable voltages (13-21) kV. The results also achieved that the values ​​of electron temperature rises from (0.2708-0.6649) eV with the increase in the applied voltage, as well as the electron density from (8.108-13.851)x1017cm-3 with the stability of the argon gas flow rate at 5 l/min. The length of the plasma was measured at different gas flow rates (1-5) l/min and different applied voltages (13-21) kV that were used in this diagnosis.

Spectral Intensity of Electron Cyclotron Radiation Emerging from the Plasma to the First Wall in ITER

It is predicted that in ITER, due to high values of electron temperature and magnetic field strength, electron cyclotron (EC) radiation emitted by plasma will be a significant source (together with external EC radiation injected for auxiliary plasma heating and non-inductive current drive) of additional thermal and electromagnetic loads for microwave and optical diagnostics. The spectral distribution of plasma EC radiation is particularly important to consider in millimeter-wave diagnostics, namely for high- and low-magnetic-field side reflectometry, plasma position reflectometry, and collective Thomson scattering diagnostic, because the transmission lines of these diagnostics yield the transport of EC waves emitted by the plasma. The development of semi-analytical methods used to describe the spectral distribution of plasma-generated EC radiation in tokamaks, starting from the work of S. Tamor, is based on the dominance of multiple reflections of this radiation from the first wall in a toroidal axially symmetric vacuum chamber. Here, we present calculations using the CYNEQ code of the spectral intensity of the EC radiation emerging from the plasma to the first wall and port plugs for five scenarios of ITER operation. This code uses the symmetry-based effect of approximate isotropy and homogeneity of radiation intensity in a substantial part of the phase space and has been successfully tested by comparison with first-principles codes. The energy flux density in the range of 30–200 kW/m2 is predicted for wall reflectance in the range of 0.6–0.95. The possible effect of this radiation on in-vessel components and diagnostics is assessed by calculating the surface density of the energy absorbed by various materials of the ITER first wall.

Spectroscopic determination of the stark broadening parameters of Al (I) 305.007 nm in atmospheric air using picosecond time-resolved LIPS

This paper intends to consider new values for the Stark broadening parameters of a singly ionized aluminum (Al I) spectral line 305.007 nm with configuration 3s3p(3P°)4s under atmospheric air conditions using a time-resolved picosecond laser-induced plasma spectroscopy (LIPS). A 100.0 mJ, 1064 nm pulse duration of 170.0 ps, Nd: YAG laser is focused on the surface of an aluminum metal target to generate plasma. The observed Al spectra are resolved using a high-resolution picometer-spectrometer, and the electron density and temperature are investigated using the delay times from 400 to 3200 ns, from the laser pulse. The spectral line of the atmospheric helium Hα line at 656.28 nm is used to estimate the plasma electron density. The Boltzmann plot method was used to consider the plasma electron temperature. The assumption of the plasma local thermodynamic equilibrium condition is verified. The electron density and temperature values were observed from 22.433 × 1017 to 0.870 × 1017 cm 3, and 13156 to 9981 K, respectively. The observed experimental values of the Stark broadening parameters of the Al I 305.007 nm varied from 0.244 to 2.156 pm and are inversely proportional to the plasma electron density and temperature values which can be helpful in the plasma fields and astronomical spectroscopy studies.

Magneto-optical properties of gapped-graphene

We theoretically study the optical properties of single-layer graphene placed on hexagonal boron nitride in the presence of a magnetic field. Analytical expressions for the longitudinal χxx(ω) and Hall χyx(ω) susceptibilities are derived from the equation of motion method. The χxx(ω) and χyx(ω) are evaluated as functions of photon energy for both undoped and doped graphenes for different values of electron densities, temperatures, and magnetic fields. The intra-band transitions induce only one peak while the inter-band ones cause a series of peaks that show oscillations with photon energy. The electron density is one of the main factors controlling the threshold energy in the doped regime. The contribution to the susceptibilities of the right polarized light is always dominant in the left polarized one.

Observation of blackbody-like emission from laser-induced plasma at early times and implications for thermal equilibrium

We present spectroscopic investigation of laser-induced plasma at an early stage of development when the Nd:Yag laser still illuminates the copper target. According to experiments during this phase the plasma nearly meets the three requirement characteristics for a black body: the spectrum is continuous and close in form to Planck’s distribution, the plasma is nontransparent, while reflectivity is close to zero. The surface temperature of the plasma is derived from continuous nearly black-body spectra, emitted by the plasma. The spectra are recorded with temporal resolution of 1 ns, and with spatial resolution of 50 μm in the axial direction. At a later stage, when the plasma becomes transparent, the absorption properties of the plasma are estimated by measuring attenuation of two low-power diagnostic CW lasers (a He–Ne 633 nm and a diode laser 400 nm) applied side-on. By assuming that inverse bremsstrahlung is the dominant absorption mechanism and by comparing absorption coefficients for 633 nm and 400 nm wavelength radiation we derived values for electron density and electron temperature inside the plasma.

Interstellar extinction correction in ionized regions using He i lines

ABSTRACT The logarithmic extinction coefficient, c(H β), is usually derived using the H α/H β ratio for case B recombination and assuming standard values of electron density and temperature. However, the use of strong Balmer lines can lead us to selection biases when studying regions with different surface brightness, such as extended nebulae, with the use of single integral field spectroscopy observations, since, in some cases, the H α line can be saturated in moderate to long exposures. In this work, we present a method to derive extinction corrections based only on the weaker lines of He i, taking into account the presence of triplet states in these atoms and its influence on recombination lines. We have applied this procedure to calculate the extinction of different regions of the 30 Doradus nebula from MUSE integral-field spectroscopy data. The comparison between helium and hydrogen c(H β) determinations has been found to yield results fully compatible within the errors and the use of both sets of lines simultaneously reduces considerably the error in the derivation.

On the applicability of three and four parameter fits for analysis of swept embedded Langmuir probes in magnetised plasma

The problem of power exhaust is one of the grand challenges of nuclear fusion research today. In order to understand the physics phenomena occurring in the scrape-off layer and the divertor regions of tokamaks, it is essential to correctly determine the divertor plasma parameters, which are often measured by swept Langmuir probes (LPs). While the construction and operation of this diagnostic can be straightforward, the data analysis using three- or four-parameter fits presents a challenge and can potentially lead to erroneous values of electron temperature and ion saturation current. In this work, we present modelling and experiments aimed at determination of conditions for proper analysis of swept LPs using these two fitting models. Particle-in-cell modelling was employed to evaluate the sheath-expansion effects for particular probe geometry and plasma conditions, yielding a semi-empirical rule capable of predicting its magnitude. Experiments with unusually wide range of swept voltage in the divertor of the COMPASS tokamak explored the magnitude of voltage range required for successful analysis with either three or four-parameter fitting. With the use of our new semi-empirical rule, it is possible to improve the four-parameter fit reliability in situations where the available voltage range is limited. In addition, we introduce the tangent method—an independent and fast method of electron temperature estimation, which allows to reliably determine the available voltage range and as such assist more complex methods of probe analysis.

Validation of edge turbulence codes against the TCV-X21 diverted L-mode reference case

Self-consistent full-size turbulent-transport simulations of the divertor and scrape-off-layer (SOL) of existing tokamaks have recently become feasible. This enables the direct comparison of turbulence simulations against experimental measurements. In this work, we perform a series of diverted ohmic L-mode discharges on the tokamak à configuration variable (TCV) tokamak, building a first-of-a-kind dataset for the validation of edge turbulence models. This dataset, referred to as TCV-X21, contains measurements from five diagnostic systems from the outboard midplane (OMP) to the divertor targets—giving a total of 45 one- and two-dimensional comparison observables in two toroidal magnetic field directions. The experimental dataset is used to validate three flux-driven 3D fluid-turbulence models—GBS, GRILLIX and TOKAM3X. With each model, we perform simulations of the TCV-X21 scenario, individually tuning the particle and power source rates to achieve a reasonable match of the upstream separatrix value of density and electron temperature. We find that the simulations match the experimental profiles for most observables at the OMP—both in terms of profile shape and absolute magnitude—while a comparatively poorer agreement is found towards the divertor targets. The match between simulation and experiment is seen to be sensitive to the value of the resistivity, the heat conductivities, the power injection rate and the choice of sheath boundary conditions. Additionally, despite targeting a sheath-limited regime, the discrepancy between simulations and experiment also suggests that the neutral dynamics should be included. The results of this validation show that turbulence models are able to perform simulations of existing devices and achieve reasonable agreement with experimental measurements. Where disagreement is found, the validation helps to identify how the models can be improved. By publicly releasing the experimental dataset and validation analysis, this work should help to guide and accelerate the development of predictive turbulence simulations of the edge and SOL.