High fusion triple product has been obtained in the advanced scenarios with high normalized beta (βN) on the Experimental Advanced Superconducting Tokamak (EAST). A record value of ni0Ti0τE ∼ 1.0 × 1019 m−3 keV s for EAST deuterium plasma has been achieved, which is due to the formation of strong and broad internal transport barriers (ITBs) in ne, Te and Ti profiles. Analysis shows that the strong ITB formation could be attributed to the reduction of transport from ITG modes. Based on the analysis, the physical mechanisms and methods to further improve the plasma performance are discussed.
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Jianyuan XIAO and Hong QIN 2021 Plasma Sci. Technol. 23 055102
Explicit structure-preserving geometric particle-in-cell (PIC) algorithm in curvilinear orthogonal coordinate systems is developed. The work reported represents a further development of the structure-preserving geometric PIC algorithm achieving the goal of practical applications in magnetic fusion research. The algorithm is constructed by discretizing the field theory for the system of charged particles and electromagnetic field using Whitney forms, discrete exterior calculus, and explicit non-canonical symplectic integration. In addition to the truncated infinitely dimensional symplectic structure, the algorithm preserves exactly many important physical symmetries and conservation laws, such as local energy conservation, gauge symmetry and the corresponding local charge conservation. As a result, the algorithm possesses the long-term accuracy and fidelity required for first-principles-based simulations of the multiscale tokamak physics. The algorithm has been implemented in the SymPIC code, which is designed for high-efficiency massively-parallel PIC simulations in modern clusters. The code has been applied to carry out whole-device 6D kinetic simulation studies of tokamak physics. A self-consistent kinetic steady state for fusion plasma in the tokamak geometry is numerically found with a predominately diagonal and anisotropic pressure tensor. The state also admits a steady-state sub-sonic ion flow in the range of 10 km s−1, agreeing with experimental observations and analytical calculations Kinetic ballooning instability in the self-consistent kinetic steady state is simulated. It is shown that high-n ballooning modes have larger growth rates than low-n global modes, and in the nonlinear phase the modes saturate approximately in 5 ion transit times at the 2% level by the E × B flow generated by the instability. These results are consistent with early and recent electromagnetic gyrokinetic simulations.
Weisheng CUI et al 2021 Plasma Sci. Technol. 23 075402
The dielectric barrier discharge (DBD) in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments. In this paper, the influence of the electric field distribution on the uniformity of DBD is theoretically analyzed and experimentally verified. It is found that a certain degree of uneven electric field distributions can control the development of electron avalanches and regulate their transition to streamers in the gap. The discharge phenomena and electrical characteristics prove that an enhanced Townsend discharge can be formed in atmospheric-pressure air with a curved-plate electrode. The spectral analysis further confirms that the gas temperature of the plasma produced by the curved-plate electrode is close to room temperature, which is beneficial for industrial applications. This paper presents the relationship between the electron avalanche transition and the formation of a uniform DBD, which can provide some references for the development and applications of the DBD in the future.
Tetsutarou OISHI et al 2021 Plasma Sci. Technol. 23 084002
An impurity powder dropper was installed in the 21st campaign of the Large Helical Device experiment (Oct. 2019–Feb. 2020) under a collaboration between the National Institute for Fusion Science and the Princeton Plasma Physics Laboratory for the purposes of real-time wall conditioning and edge plasma control. In order to assess the effective injection of the impurity powders, spectroscopic diagnostics were applied to observe line emission from the injected impurity. Thus, extreme-ultraviolet (EUV) and vacuum-ultraviolet (VUV) emission spectra were analyzed to summarize observable impurity lines with B and BN powder injection. Emission lines released from B and N ions were identified in the EUV wavelength range of 5–300 Å measured using two grazing incidence flat-field EUV spectrometers and in the VUV wavelength range of 300–2400 Å measured using three normal incidence 20 cm VUV spectrometers. BI–BV and NIII–NVII emission lines were identified in the discharges with the B and BN powder injection, respectively. Useful B and N emission lines which have large intensities and are isolated from other lines were successfully identified as follows: BI (1825.89, 1826.40) Å (blended), BII 1362.46 Å, BIII (677.00, 677.14, 677.16) Å (blended), BIV 60.31 Å, BV 48.59 Å, NIII (989.79, 991.51, 991.58) Å (blended), NIV 765.15 Å, NV (209.27, 209.31) Å (blended), NVI 1896.80 Å, and NVII 24.78 Å. Applications of the line identifications to the advanced spectroscopic diagnostics were demonstrated, such as the vertical profile measurements for the BV and NVII lines using a space-resolved EUV spectrometer and the ion temperature measurement for the BII line using a normal incidence 3 m VUV spectrometer.
Ruchen SHU et al 2024 Plasma Sci. Technol. 26 075502
The ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate treated with radiofrequency plasma is proposed for functionalization and immobilization on polyethersulfone supports to form supported ionic liquid membranes for CO2 separation. The effects of treatment time and transmembrane pressure difference on CO2 permeance were evaluated. The best gas permeation performance was obtained with a treatment time of 10 min and the transmembrane pressure difference was 0.25 MPa. Characterization of the materials by Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy demonstrates that the IL is grafted with carboxyl groups and deprotonated through plasma treatment. A preliminary mechanism for the plasma treatment and facilitated transport of CO2 has been proposed on this basis.
Yang ZHAO et al 2024 Plasma Sci. Technol. 26 075402
Enhancing plasma uniformity can be achieved by modifying coil and chamber structures in radio frequency inductively coupled plasma (ICP) to meet the demand for large-area and uniformly distributed plasma in industrial manufacturing. This study utilized a two-dimensional self-consistent fluid model to investigate how different coil configurations and chamber aspect ratios affect the radial uniformity of plasma in radio frequency ICP. The findings indicate that optimizing the radial spacing of the coil enhances plasma uniformity but with a reduction in electron density. Furthermore, optimizing the coil within the ICP reactor, using the interior point method in the Interior Point Optimizer significantly enhances plasma uniformity, elevating it from 56% to 96% within the range of the model sizes. Additionally, when the chamber aspect ratio k changes from 2.8 to 4.7, the plasma distribution changes from a center-high to a saddle-shaped distribution. Moreover, the plasma uniformity becomes worse. Finally, adjusting process parameters, such as increasing source power and gas pressure, can enhance plasma uniformity. These findings contribute to optimizing the etching process by improving plasma radial uniformity.
Xiaofang XU et al 2024 Plasma Sci. Technol. 26 064005
Ammonia is one of the most important chemical raw materials in both manufacture and life of human. Traditionally Haber-Bosch method for ammonia synthesis involves high temperature and high pressure conditions, leading to significant energy consumption and environmental pollution. Non-thermal plasma (NTP) is a promising alternative approach to ammonia synthesis at low temperature and atmospheric pressure. In this study, the synergistic effect of nanosecond pulsed dielectric barrier discharge (np-DBD) and Ni-MOF-74 catalyst was investigated in ammonia synthesis by utilizing nitrogen and hydrogen as feedstock. The results demonstrated that the plasma catalytic-synthesis process parameters play a crucial role in the synthesis process of ammonia. The highest ammonia synthesis rate of 5145.16 μmol·g−1·h−1 with an energy efficiency of 1.27 g·kWh−1 was observed in the presence of the Ni-MOF-74 catalyst, which was 3.7 times higher than that without Ni-MOF-74 catalyst. The synergistic effect of Ni-MOF-74 catalyst and nanosecond pulsed plasma was explored by in-situ plasma discharge diagnostics.
Liang QIN et al 2024 Plasma Sci. Technol. 26 075401
In this paper, self-designed multi-hollow needle electrodes are used as a high-voltage electrode in a packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large-volume stable discharge. The dynamic characteristics of the plasma, the generated active species, and the energy transfer mechanisms in both positive discharge (PD) and negative discharge (ND) are investigated by using fast-exposure intensified charge coupled device (ICCD) images and time-resolved optical emission spectra. The experimental results show that the discharge intensity, number of discharge channels, and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multi-hollow needle electrode. During a single voltage pulse period, PD mainly develops in a streamer mode, which results in a stronger discharge current, luminous intensity, and E/N compared with the diffuse mode observed in ND. In PD, as the gap between dielectric beads changes from 0 to 250 μm, the discharge between the dielectric bead gap changes from a partial discharge to a standing filamentary micro-discharge, which allows the plasma to leave the local area and is conducive to the propagation of surface streamers. In ND, the discharge only appears as a diffusion-like mode between the gap of dielectric beads, regardless of whether there is a discharge gap. Moreover, the generation of excited states and is mainly observed in PD, which is attributed to the higher E/N in PD than that in ND. However, the generation of the radical in ND is higher than in PD. It is not directly dominated by E/N, but mainly by the resonant energy transfer process between metastable and . Furthermore, both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration, and no vibration-to-rotation energy relaxation process is observed.
Tao WANG et al 2024 Plasma Sci. Technol. 26 053001
In a tokamak fusion reactor operated at steady state, the equilibrium magnetic field is likely to have reversed shear in the core region, as the noninductive bootstrap current profile generally peaks off-axis. The reversed shear Alfvén eigenmode (RSAE) as a unique branch of the shear Alfvén wave in this equilibrium, can exist with a broad spectrum in wavenumber and frequency, and be resonantly driven unstable by energetic particles (EP). After briefly discussing the RSAE linear properties in burning plasma condition, we review several key topics of the nonlinear dynamics for the RSAE through both wave-EP resonance and wave-wave coupling channels, and illustrate their potentially important role in reactor-scale fusion plasmas. By means of simplified hybrid MHD-kinetic simulations, the RSAEs are shown to have typically broad phase space resonance structure with both circulating and trapped EP, as results of weak/vanishing magnetic shear and relatively low frequency. Through the route of wave-EP nonlinearity, the dominant saturation mechanism is mainly due to the transported resonant EP radially decoupling with the localized RSAE mode structure, and the resultant EP transport generally has a convective feature. The saturated RSAEs also undergo various nonlinear couplings with other collective oscillations. Two typical routes as parametric decay and modulational instability are studied using nonlinear gyrokinetic theory, and applied to the scenario of spontaneous excitation by a finite amplitude pump RSAE. Multiple RSAEs could naturally couple and induce the spectral energy cascade into a low frequency Alfvénic mode, which may effectively transfer the EP energy to fuel ions via collisionless Landau damping. Moreover, zero frequency zonal field structure could be spontaneously excited by modulation of the pump RSAE envelope, and may also lead to saturation of the pump RSAE by both scattering into stable domain and local distortion of the continuum structure.
Tatiana HABIB et al 2024 Plasma Sci. Technol. 26 075505
Homogeneous gold nanoparticles were synthesized under atmospheric pressure using a non-thermal helium plasma jet in a single-step process. A current power supply was used to generate the plasma discharge rich in diverse reactive species. These species induce rapid chemical reactions responsible for the reduction of the gold salts upon contact with the liquid solution. In this study, spherical and monodispersed gold nanoparticles were obtained within 5 min of plasma exposure using a solution containing gold (III) chloride hydrate (HAuCl4) as a precursor and polyvinylpyrrolidone (PVP) as a capping agent to inhibit agglomerations. The formation of these metal nanoparticles was initially perceptible through a visible change in the sample's color, transitioning from light yellow to a red/pink color. This was subsequently corroborated by UV-vis spectroscopy, which revealed an optical absorption in the 520‒550 nm range for Au NPs, corresponding to the surface plasmon resonance (SPR) band. An investigation into the impact of various parameters, including plasma discharge duration, precursor and capping agent concentrations, was carried out to optimize conditions for the formation of well-separated, spherical gold nanoparticles. Dynamic light scattering (DLS) was used to measure the size of these nanoparticles, transmission electron microscopy (TEM) was used to observe their morphology and X-ray diffraction (XRD) was also employed to determine their crystallographic structure. The results confirm that homogeneous spherical gold nanoparticles with an average diameter of 13 nm can be easily synthesized through a rapid, straightforward, and environmentally friendly approach utilizing a helium atmospheric pressure plasma.
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Ruchen SHU et al 2024 Plasma Sci. Technol. 26 075502
The ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate treated with radiofrequency plasma is proposed for functionalization and immobilization on polyethersulfone supports to form supported ionic liquid membranes for CO2 separation. The effects of treatment time and transmembrane pressure difference on CO2 permeance were evaluated. The best gas permeation performance was obtained with a treatment time of 10 min and the transmembrane pressure difference was 0.25 MPa. Characterization of the materials by Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy and nuclear magnetic resonance spectroscopy demonstrates that the IL is grafted with carboxyl groups and deprotonated through plasma treatment. A preliminary mechanism for the plasma treatment and facilitated transport of CO2 has been proposed on this basis.
Yizhuohang LIU et al 2024 Plasma Sci. Technol. 26 075101
According to the physics of tokamak start-up, this study constructs a zero-dimensional (0D) model applicable to electron cyclotron (EC) wave assisted start-up in NCST spherical torus (spherical tokamak) and CN-H1 stellarators. Using the constructed 0D model, the results obtained in this study under the same conditions are compared and validated against reference results for pure hydrogen plasma start-up in tokamak. The results are in good agreement, especially regarding electron temperature, ion temperature and plasma current. In the presence of finite Ohmic electric field in the spherical tokamak, a study on the EC wave assisted start-up of the NCST plasma at frequency of 28 GHz is conducted. The impact of the vertical magnetic field Bv on EC wave assisted start-up, the relationship between EC wave injection power Pinj, Ohmic electric field E, and initial hydrogen atom density nH0 are explored separately. It is found that under conditions of Ohmic electric field lower than ITER (~ 0.3 V m−1), EC wave can expand the operational space to achieve better plasma parameters. Simulating the process of 28 GHz EC wave start-up in the CN-H1 stellarator plasma, the plasma current in the zero-dimensional model is replaced with the current in the poloidal coil of the stellarator. Plasma start-up can be successfully achieved at injection powers in the hundreds of kilowatts range, resulting in electron densities on the order of 1017–1018 m–3.
Liang QIN et al 2024 Plasma Sci. Technol. 26 075401
In this paper, self-designed multi-hollow needle electrodes are used as a high-voltage electrode in a packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large-volume stable discharge. The dynamic characteristics of the plasma, the generated active species, and the energy transfer mechanisms in both positive discharge (PD) and negative discharge (ND) are investigated by using fast-exposure intensified charge coupled device (ICCD) images and time-resolved optical emission spectra. The experimental results show that the discharge intensity, number of discharge channels, and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multi-hollow needle electrode. During a single voltage pulse period, PD mainly develops in a streamer mode, which results in a stronger discharge current, luminous intensity, and E/N compared with the diffuse mode observed in ND. In PD, as the gap between dielectric beads changes from 0 to 250 μm, the discharge between the dielectric bead gap changes from a partial discharge to a standing filamentary micro-discharge, which allows the plasma to leave the local area and is conducive to the propagation of surface streamers. In ND, the discharge only appears as a diffusion-like mode between the gap of dielectric beads, regardless of whether there is a discharge gap. Moreover, the generation of excited states and is mainly observed in PD, which is attributed to the higher E/N in PD than that in ND. However, the generation of the radical in ND is higher than in PD. It is not directly dominated by E/N, but mainly by the resonant energy transfer process between metastable and . Furthermore, both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration, and no vibration-to-rotation energy relaxation process is observed.
Yang ZHAO et al 2024 Plasma Sci. Technol. 26 075402
Enhancing plasma uniformity can be achieved by modifying coil and chamber structures in radio frequency inductively coupled plasma (ICP) to meet the demand for large-area and uniformly distributed plasma in industrial manufacturing. This study utilized a two-dimensional self-consistent fluid model to investigate how different coil configurations and chamber aspect ratios affect the radial uniformity of plasma in radio frequency ICP. The findings indicate that optimizing the radial spacing of the coil enhances plasma uniformity but with a reduction in electron density. Furthermore, optimizing the coil within the ICP reactor, using the interior point method in the Interior Point Optimizer significantly enhances plasma uniformity, elevating it from 56% to 96% within the range of the model sizes. Additionally, when the chamber aspect ratio k changes from 2.8 to 4.7, the plasma distribution changes from a center-high to a saddle-shaped distribution. Moreover, the plasma uniformity becomes worse. Finally, adjusting process parameters, such as increasing source power and gas pressure, can enhance plasma uniformity. These findings contribute to optimizing the etching process by improving plasma radial uniformity.
Rui TAN et al 2024 Plasma Sci. Technol. 26 075503
Magnetic field design is essential for the operation of Hall thrusters. This study focuses on utilizing a genetic algorithm to optimize the magnetic field configuration of SPT70. A 2D hybrid PIC-DSMC and channel-wall erosion model are employed to analyze the plume divergence angle and wall erosion rate, while a Farady probe measurement and laser profilometry system are set up to verify the simulation results. The results demonstrate that the genetic algorithm contributes to reducing the divergence angle of the thruster plumes and alleviating the impact of high-energy particles on the discharge channel wall, reducing the erosion by 5.5% and 2.7%, respectively. Further analysis indicates that the change from a divergent magnetic field to a convergent magnetic field, combined with the upstream shift of the ionization region, contributes to the improving the operation of the Hall thruster.
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Jiacheng LI et al 2023 Plasma Sci. Technol. 25 093001
Hydrogels are biomaterials with 3D networks of hydrophilic polymers. The generation of hydrogels is turning to the development of hydrogels with the help of enabling technologies. Plasma can tailor the hydrogels' properties through simultaneous physical and chemical actions, resulting in an emerging technology of plasma-activated hydrogels (PAH). PAH can be divided into functional PAH and biological tissue model PAH. This review systematically introduces the plasma sources, plasma etching polymer surface, and plasma cross-linking involved in the fabrication of PAH. The 'diffusion-drift-reaction model' is used to study the microscopic physicochemical interaction between plasma and biological tissue PAH models. Finally, the main achievements of PAH, including wound treatment, sterilization, 3D tumor model, etc, and their development trends are discussed.
Heping LI et al 2022 Plasma Sci. Technol. 24 093001
Cold atmospheric plasmas (CAPs) have shown great applicability in agriculture. Many kinds of CAP sources have been studied in agricultural applications to promote plant growth and cure plant diseases. We briefly review the state-of-the-art stimulating effects of atmospheric-pressure dielectric-barrier-discharge (AP-DBD) plasmas, after the direct or indirect treatment of plants for growth promotion and disease control. We then discuss the special demands on the characteristics of the CAP sources for their applications in plant mutation breeding. An atmospheric and room temperature plasma (ARTP) jet generator with a large plasma irradiation area, a high enough concentration of chemically reactive species and a low gas temperature is designed for direct plant mutagenesis. Experimental measurements of the electrical, thermal and optical features of the ARTP generator are conducted. Then, an ARTP-P (ARTP for plant mutagenesis) mutation breeding machine is developed, and a typical case of plant mutation breeding by the ARTP-P mutation machine is presented using Coreopsis tinctoria Nutt. seeds. Physical and agricultural experiments show that the newly-developed ARTP-P mutation breeding machine with a large irradiation area can generate uniform CAP jets with high concentrations of chemically reactive species and mild gas temperatures, and have significant mutagenesis effects on the Coreopsis tinctoria Nutt. seeds. The ARTP-P mutation breeding machine may provide a platform for systematic studies on mutation mechanisms and results for various plant seeds under different operating conditions in future research.
Zhengxiong WANG et al 2022 Plasma Sci. Technol. 24 033001
This paper reviews the effects of resonant magnetic perturbation (RMP) on classical tearing modes (TMs) and neoclassical tearing modes (NTMs) from the theory, experimental discovery and numerical results with a focus on four major aspects: (i) mode mitigation, where the TM/NTM is totally suppressed or partly mitigated by the use of RMP; (ii) mode penetration, which means a linearly stable TM/NTM triggered by the externally applied RMP; (iii) mode locking, namely an existing rotating magnetic island braked and finally stopped by the RMP; (iv) mode unlocking, as the name suggests, it is the reverse of the mode locking process. The key mechanism and physical picture of above phenomena are revealed and summarized.
Zimu XU et al 2020 Plasma Sci. Technol. 22 103001
Atmospheric pressure cold plasma, with advantages such as high particle activity, no thermal damage, high efficiency and direct and friendly contact with human tissues, is considered to have great potential in biomedical applications. Therefore, 'plasma medicine' as a new interdiscipline has been developed in the past two decades. This review first briefly describes the development of typical plasma sources suitable for biomedical applications, and those with different discharge forms are simply compared, evaluated and summarized. Subsequently, measurement of the crucial gaseous reactive particles (e.g. OH and O) and their spatio-temporal distributions are introduced. Meanwhile, the generation and variation rules and the related critical macroscopic parameters of the plasma-induced aqueous reactive species are summarized. Finally, related studies in the last ten years on the mechanisms of the plasma-driven microbial inactivation and plasma-induced apoptosis of cancer cells are introduced. Moreover, some scientific problems that need to be urgently solved in the field of plasma medicine are also discussed. This review will provide useful guidance for future related research.
Min JIANG et al 2020 Plasma Sci. Technol. 22 080501
The influence of m/n = 2/1 (m and n are poloidal and toroidal mode numbers) tearing modes on plasma perpendicular flows and micro-fluctuations has been investigated in HL-2A neutral beam injection heated L-mode plasmas. It is found that the local perpendicular rotation velocity and turbulence energy are modulated by the alternation between the island X-point and O-point of the naturally rotating tearing modes. Cross-correlation analysis indicates that the modulation of density fluctuations by the tearing mode is not only limited to the island region, but also occurs in the edge region near the last closed flux surface. The turbulence exhibits distinct spectral characteristics inside and outside the island region. In addition, it is observed that the particle flux near the strike point is also significantly impacted by the tearing modes. The experimental evidence reveals that there are strong core-edge interactions between the core tearing modes and the edge transport.
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Qin et al
The plasma sterilization is a new generation of high-tech sterilization method, with the characteristics of fast, safe and pollution-free, widely used in medical, food and environmental protection fields. Home air sterilization is an emerging field of plasma application, which puts higher requirements on the miniaturization, operational stability, and operating cost of plasma device. In this paper, a novel magnetic driven rotating gliding arc (MDRGA) discharge device was used to sterilize lactobacillus fermentation. Compared to the traditional gas driven gliding arc, this device has a simple structure and more stable gliding arc. Simulation using COMSOL Multiphysics showed that adding permanent magnets can form a stable magnetic field, which is conducive to the formation of gliding arcs. Experiments were conducted on discharge performance, ozone concentration, and sterilization effect under different power supply parameters. The results revealed that the process of MDRGA can be divided into three stages: starting, gliding and extinguishing. The appropriate voltage was the key factor for stable arc gliding, and both high and low voltages were not conducive to stable arc gliding and Ozone production. For this experimental setup, the sterilization effect was best at 6.6 kV. High modulation duty ratio was beneficial for stable arc gliding, however, when the duty ratio exceeds a certain value, the improvement in sterilization effect was slow. So, considering the sterilization effect and energy factors comprehensively, for this experimental device, we choose 80% as the optimal modulation duty ratio.
Zhao et al
Effects of three-dimensional (3D) magnetic field perturbations due to feedback control of an unstable n = 1 (n is toroidal mode number) resistive wall mode (RWM) on the energetic particle (EP) losses are systematically investigated for the HL-3 tokamak. The MARS-F (Liu et al 2000 Phys. Plasmas 7 3681) code, facilitated by the test particle guiding center tracing module REORBIT, is utilized for the study. The RWM is found to generally produce no EP loss for co-current particles in HL-3. Assuming the same perturbation level at the sensor location for the close-loop system, feedback produces nearly the same loss of counter-current EPs compared to the open-loop case. Assuming however that the sensor signal is ten times smaller in the close-loop system than the open-loop counter part (reflecting the fact that the RWM is more stable with feedback), the counter-current EP loss is found significantly reduced in the former. Most of EP losses occur only for particles launched close to the plasma edge, while particles launched further away from the plasma boundary experience much less loss. The strike points of lost EPs on the HL-3 limiting surface become more scattered for particles launched closer to the plasma boundary. Taking into account the full gyro-orbit of particles while approaching the limiting surface, REORBIT finds slightly enhanced loss fraction.
Li et al
Plasma-based processes, particularly in carbon capture and utilization, hold great potential for addressing environmental challenges and advancing a circular carbon economy. While significant progress has been made in understanding plasma-induced reactions, plasma-catalyst interactions, and reactor development to enhance energy efficiency and conversion, there remains a notable gap in research concerning overall process development. This review emphasizes the critical need for considerations at the process level, including integration and intensification, to facilitate the industrialization of plasma technology for chemical production. Discussions centered on the development of plasma-based processes are made with a primary focus on CO2 conversion, offering insights to guide future work for the transition of the technology from laboratory scale to industrial applications. Identification of current research gaps, especially in upscaling and integrating plasma reactors with other process units, is the key to addressing critical issues. The review further delves into relevant research in process evaluation and assessment, providing methodological insights and highlighting key factors for comprehensive economic and sustainability analyses. Additionally, recent advancements in novel plasma systems are reviewed, presenting unique advantages and innovative concepts that could reshape the future of process development. This review provides essential information for navigating the path forward, ensuring a comprehensive understanding of challenges and opportunities in the development of plasma-based CCU process.
Wen et al
Measurements of the total radiated power and its spatial distribution are crucial for fusion research. On the experimental advanced superconducting tokamak (EAST), both the metal foil resistive bolometer and the absolute extreme ultraviolet (AXUV) photodiodes have been used to quantify the radiated power. This article introduces the latest improvement of the bolometer diagnostic system on EAST. It also details the successful design and installation of new divertor AXUV cameras, which are dedicated to the investigation of divertor physics. The shielding components of the bolometer detector have been refined, and the article provides a detailed exposition of the double shielding structures that have been verified as effective in microwave shielding. Additionally, the changes in the radiated power distribution in the divertor region during the plasma detachment process are measured using the divertor AXUV camera. Finally, the radiated power measured by the AXUV detector and metal foil resistive bolometer are compared, and different detector performances are presented.
Wang et al
In this study, a single dielectric barrier discharge (DBD) coaxial reactor was used to degrade 4, 4'-sulfonylbis (TBBPS) in water using greenhouse gas (CO2) and argon as the carrier gases. The investigation focused on CO2 conversion, reactive species formation, gas-liquid mass transfer mechanism, and degradation mechanism of TBBPS during the discharge plasma process. With the decrease of CO2/Ar ratio in the process of plasma discharge, the emission spectrum intensity of Ar, CO2 and excited reactive species was enhanced. This increase promoted collision and dissociation of CO2, resulting in a series of chemical reactions that improved the production of reactive species such as ·OH, 1O2, H2O2 and O3. These reactive species initiated a sequence of reactions with TBBPS. Results indicated that at a gas flow rate of 240 mL/min with a CO2/Ar ratio of 1:5, both the highest CO2 conversion rate (17.76%) and TBBPS degradation rate (94.24%) were achieved. The degradation mechanism was elucidated by determining types and contents of reactive species present in treatment liquid along with analysis of intermediate products using liquid chromatography-mass spectrometry techniques. This research provides novel insights into carbon dioxide utilization and water pollution control through dielectric barrier discharge plasma technology.