Pub Date : 2023-10-06DOI: 10.1088/1361-6463/ad00c9
Bin Ni, Wei Chen, Shengwei Ye, Lu Xue, Lianping Hou, John Haig Marsh, Kai Gu, Chaofu Sun, Xuefeng Liu, Jichuan Xiong
Abstract In this paper, a novel polarization parametric indirect microscopic imaging (PIMI) method is utilized for the first time to characterize the near-field emission mode and end-face structure of nanoscale semiconductor light-emitting chips. Via polarization modulation and detection of the emitted light from an SLD chip, abundant information including the distinct border of the emission mode, which cannot be seen by the traditional method, is collected and visualized as the form of multi-dimensional photon state distribution images. The polarization property distribution of the emission mode was visualized for the first time. Besides, by concurrent analysis of PIMI images of the end-face structure and emission mode, potential impurities adhered to the emitting facet can be precisely screened and located. The proposed method here has considerable advantages in the characterization of the light-emitting devices, paving a new way for precise, convenient, cost-effective, and large-scale quality inspection in industries.
{"title":"Characterization of Near-field Emission and Structure of an SLD by Polarization Parametric Indirect Microscopic Imaging","authors":"Bin Ni, Wei Chen, Shengwei Ye, Lu Xue, Lianping Hou, John Haig Marsh, Kai Gu, Chaofu Sun, Xuefeng Liu, Jichuan Xiong","doi":"10.1088/1361-6463/ad00c9","DOIUrl":"https://doi.org/10.1088/1361-6463/ad00c9","url":null,"abstract":"Abstract In this paper, a novel polarization parametric indirect microscopic imaging (PIMI) method is utilized for the first time to characterize the near-field emission mode and end-face structure of nanoscale semiconductor light-emitting chips. Via polarization modulation and detection of the emitted light from an SLD chip, abundant information including the distinct border of the emission mode, which cannot be seen by the traditional method, is collected and visualized as the form of multi-dimensional photon state distribution images. The polarization property distribution of the emission mode was visualized for the first time. Besides, by concurrent analysis of PIMI images of the end-face structure and emission mode, potential impurities adhered to the emitting facet can be precisely screened and located. The proposed method here has considerable advantages in the characterization of the light-emitting devices, paving a new way for precise, convenient, cost-effective, and large-scale quality inspection in industries.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"299 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134944568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-06DOI: 10.1088/1361-6463/acfd38
Kazunori Maebuchi, Norio Inui
Abstract Graphene exhibits diamagnetism, and its origin is the orbital electric currents induced on the surface by an applied magnetic field. The magnetic response of a graphene cantilever in the presence of a magnetic field is mainly determined by the diamagnetic electric current, and spin paramagnetism, which suppresses the diamagnetism. We elucidate the change in the electric current distribution caused by the large bending of the graphene cantilever using the tight-binding model. The electric current almost disappears when the position of the graphene cantilever transitions from perpendicular to parallel to the magnetic field and reverses when the graphene cantilever is folded in half. Furthermore, the temporal change in the magnetic energy of the vibrating graphene cantilever is calculated using the molecular dynamics simulation. The strong dependence of the magnetization of a graphene cantilever on its position relative to the magnetic field can be utilized for actuating and controlling the cantilever.
{"title":"Electric current distribution induced by applied magnetic field in a bent graphene nanoribbon cantilever","authors":"Kazunori Maebuchi, Norio Inui","doi":"10.1088/1361-6463/acfd38","DOIUrl":"https://doi.org/10.1088/1361-6463/acfd38","url":null,"abstract":"Abstract Graphene exhibits diamagnetism, and its origin is the orbital electric currents induced on the surface by an applied magnetic field. The magnetic response of a graphene cantilever in the presence of a magnetic field is mainly determined by the diamagnetic electric current, and spin paramagnetism, which suppresses the diamagnetism. We elucidate the change in the electric current distribution caused by the large bending of the graphene cantilever using the tight-binding model. The electric current almost disappears when the position of the graphene cantilever transitions from perpendicular to parallel to the magnetic field and reverses when the graphene cantilever is folded in half. Furthermore, the temporal change in the magnetic energy of the vibrating graphene cantilever is calculated using the molecular dynamics simulation. The strong dependence of the magnetization of a graphene cantilever on its position relative to the magnetic field can be utilized for actuating and controlling the cantilever.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135302310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-06DOI: 10.1088/1361-6463/acfcc6
Marley Becerra, Janne Nilsson, Steffen Franke, Cornelia Breitkopf, Pascal Andre
Abstract Plasma diagnostics is a key tool to support the further development of plasma-induced chemical conversion of greenhouse gases (such as CO 2 ) into high-value chemicals. For this reason, spectroscopic and electric measurements of low current (below 1.7 A), stationary arc plasmas in CO 2 at atmospheric pressure with addition of N 2 or H 2 O are reported. High-speed photography, imaging emission spectroscopy and time-resolved electrical measurements are used to obtain time-space resolved gas temperatures as well as the electric-field current characteristics of the discharge. It is found that the lowest average electric field in a CO 2 arc plasma at atmospheric pressure is ∼20 kV mm −1 at a current between 0.8 and 1 A. If the current decreases below this level, the arc remains in vibrational–translational (VT) equilibrium by increasing the electric field. However, VT equilibrium conditions can be only maintained until a threshold minimum current of 0.33 ± 0.05 A, at which the arc transitions into a non-equilibrium condition with further increasing electric fields (reaching 68 ± 15 V mm −1 at 0.03 A). The addition of N 2 or H 2 O did not influence the electrical characteristics of the CO 2 arc within to the tested mixtures. However, there is only a significant decrease in the electric field of the formed transition arcs and the threshold minimum current in the presence of N 2 . The spectra of the low-current CO 2 arc is found to be dominated by emission from the C 2 Swan band system and the O I 777 nm triplet peak. However, the CN band dominates the spectra even when small amounts (0.5 wt%) of N 2 is present in the plasma. The gas temperature at the axis of the CO 2 arc plasma decreased slightly with decreasing current, from an estimated 7000 K at 1 A down to 6300 K at 0.4 A. The thermal radius of the arc is estimated to be larger than 1.2 mm, more than two times larger than the optical radius obtained from the emitted radiation. The addition of N 2 and H 2 O (up to 7 and 9 wt% respectively) lead to only to a 500 K decrease in the axial arc temperature.
{"title":"Spectral and Electric Diagnostics of Low-current Arc Plasmas in CO<sub>2</sub> with N<sub>2</sub> and H<sub>2</sub>O admixtures","authors":"Marley Becerra, Janne Nilsson, Steffen Franke, Cornelia Breitkopf, Pascal Andre","doi":"10.1088/1361-6463/acfcc6","DOIUrl":"https://doi.org/10.1088/1361-6463/acfcc6","url":null,"abstract":"Abstract Plasma diagnostics is a key tool to support the further development of plasma-induced chemical conversion of greenhouse gases (such as CO 2 ) into high-value chemicals. For this reason, spectroscopic and electric measurements of low current (below 1.7 A), stationary arc plasmas in CO 2 at atmospheric pressure with addition of N 2 or H 2 O are reported. High-speed photography, imaging emission spectroscopy and time-resolved electrical measurements are used to obtain time-space resolved gas temperatures as well as the electric-field current characteristics of the discharge. It is found that the lowest average electric field in a CO 2 arc plasma at atmospheric pressure is ∼20 kV mm −1 at a current between 0.8 and 1 A. If the current decreases below this level, the arc remains in vibrational–translational (VT) equilibrium by increasing the electric field. However, VT equilibrium conditions can be only maintained until a threshold minimum current of 0.33 ± 0.05 A, at which the arc transitions into a non-equilibrium condition with further increasing electric fields (reaching 68 ± 15 V mm −1 at 0.03 A). The addition of N 2 or H 2 O did not influence the electrical characteristics of the CO 2 arc within to the tested mixtures. However, there is only a significant decrease in the electric field of the formed transition arcs and the threshold minimum current in the presence of N 2 . The spectra of the low-current CO 2 arc is found to be dominated by emission from the C 2 Swan band system and the O I 777 nm triplet peak. However, the CN band dominates the spectra even when small amounts (0.5 wt%) of N 2 is present in the plasma. The gas temperature at the axis of the CO 2 arc plasma decreased slightly with decreasing current, from an estimated 7000 K at 1 A down to 6300 K at 0.4 A. The thermal radius of the arc is estimated to be larger than 1.2 mm, more than two times larger than the optical radius obtained from the emitted radiation. The addition of N 2 and H 2 O (up to 7 and 9 wt% respectively) lead to only to a 500 K decrease in the axial arc temperature.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135302456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-05DOI: 10.1088/1361-6463/acfd39
Audren Dorval, Luc Stafford, Ahmad Hamdan
Abstract Spark discharges in liquid have shown great potential for use in numerous applications, such as pollutant degradation, precision micromachining, and nanomaterials production. Herein, spark discharges are initiated at the interface of two immiscible liquids, heptane and water. This leads to the formation of an emulsion via mechanisms akin to bubble dynamics and instabilities at the gas–liquid. At high discharge number, an additional mechanism contributes to emulsion formation, resulting in an increase in the number of smaller heptane droplets in water. Analyses of the current–voltage characteristics show that high probability of discharge occurrence is obtained when the electrodes are aligned with the interface. This result is correlated with the low erosion rate of the electrodes. In the case of discharges at the interface, we observed that beyond a certain number of discharges, the breakdown voltage drops; far from the interface, it increases with the discharge number. Based on 2D simulation with a Monte Carlo approach to consider various droplet distribution in water, the electric field distribution is determined. The results support the fact that the decrease in breakdown voltage may be attributed to the intensification of the E -field in water close the heptane droplet. Therefore, spark discharges generated at the interface of a heptane/water system produce an emulsion of heptane in water, which facilitates the occurrence of subsequent discharges by intensifying the electric field and reducing the breakdown voltage.
{"title":"Spark discharges at the interface of water and heptane: Emulsification and effect on discharge probability","authors":"Audren Dorval, Luc Stafford, Ahmad Hamdan","doi":"10.1088/1361-6463/acfd39","DOIUrl":"https://doi.org/10.1088/1361-6463/acfd39","url":null,"abstract":"Abstract Spark discharges in liquid have shown great potential for use in numerous applications, such as pollutant degradation, precision micromachining, and nanomaterials production. Herein, spark discharges are initiated at the interface of two immiscible liquids, heptane and water. This leads to the formation of an emulsion via mechanisms akin to bubble dynamics and instabilities at the gas–liquid. At high discharge number, an additional mechanism contributes to emulsion formation, resulting in an increase in the number of smaller heptane droplets in water. Analyses of the current–voltage characteristics show that high probability of discharge occurrence is obtained when the electrodes are aligned with the interface. This result is correlated with the low erosion rate of the electrodes. In the case of discharges at the interface, we observed that beyond a certain number of discharges, the breakdown voltage drops; far from the interface, it increases with the discharge number. Based on 2D simulation with a Monte Carlo approach to consider various droplet distribution in water, the electric field distribution is determined. The results support the fact that the decrease in breakdown voltage may be attributed to the intensification of the E -field in water close the heptane droplet. Therefore, spark discharges generated at the interface of a heptane/water system produce an emulsion of heptane in water, which facilitates the occurrence of subsequent discharges by intensifying the electric field and reducing the breakdown voltage.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134946661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-05DOI: 10.1088/1361-6463/acfa0c
Jian-Qiao Han, Fan-Yi Meng, Xiaolong Wang, Yu-Hang Liu, Chang Ding, Tao Jin, Guan-Long Huang, Shan-Shan Xu, Bo Lv, Qun Wu
Abstract A 1-bit phase reconfigurable fixed-frequency beam steering leaky-wave antenna (FBSLWA) with wide-angle steering is proposed in this paper. By controlling two p–i–n diodes on the branches of the element, a stable 180° phase difference is realized. Moreover, the open stop-band effect at the broadside radiation is suppressed by reducing the reflection coefficients of the element. The proposed FBSLWA can achieve wide-angle steering within a frequency bandwidth of 10.4 GHz–11.8 GHz. As for the measured results, they show that the achievable beam steering ranges of the FBSLWA at 10.4 GHz, 11.0 GHz, and 11.8 GHz are −61° to +59°, −64° to +71°, and −62° to +58° respectively, with measured peak gains of 12.1 dBi, 13.9 dBi, and 11.7 dBi.
{"title":"A 1-Bit Phase Reconfigurable Fixed-Frequency Wide-Angle Steering Leaky-Wave Antenna","authors":"Jian-Qiao Han, Fan-Yi Meng, Xiaolong Wang, Yu-Hang Liu, Chang Ding, Tao Jin, Guan-Long Huang, Shan-Shan Xu, Bo Lv, Qun Wu","doi":"10.1088/1361-6463/acfa0c","DOIUrl":"https://doi.org/10.1088/1361-6463/acfa0c","url":null,"abstract":"Abstract A 1-bit phase reconfigurable fixed-frequency beam steering leaky-wave antenna (FBSLWA) with wide-angle steering is proposed in this paper. By controlling two p–i–n diodes on the branches of the element, a stable 180° phase difference is realized. Moreover, the open stop-band effect at the broadside radiation is suppressed by reducing the reflection coefficients of the element. The proposed FBSLWA can achieve wide-angle steering within a frequency bandwidth of 10.4 GHz–11.8 GHz. As for the measured results, they show that the achievable beam steering ranges of the FBSLWA at 10.4 GHz, 11.0 GHz, and 11.8 GHz are −61° to +59°, −64° to +71°, and −62° to +58° respectively, with measured peak gains of 12.1 dBi, 13.9 dBi, and 11.7 dBi.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134948055","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract In this paper, ultra-wideband and wide-angle radar cross section (RCS) reduction of a concave structure is designed and realized based on a chessboard polarization conversion metasurface (CPCM), employing an ultra-wideband polarization conversion metasurface (PCM) composed of a single layer of square split-ring resonators. The concave structure, which is equivalent to an octagonal-like prism, is divided into eight regions. To achieve perfect phase cancellation in the non-central region, it can be equivalent to oblique incidence when the central region is under normal incidence, and phase compensation of the unit cell of metasurfaces in the non-central region is considered. The simulated results demonstrate that the RCS reduction of the proposed concave structure is less than -10 dB in the frequency ranges of 8.8 GHz to 35.75 GHz with fractional bandwidths of 120.99% and exceeds -30 dB at numerous resonant frequencies such as 9.52 GHz, 13.89 GHz, 23.45 GHz, and 35.2 GHz under normal incidence. The experimental results are in good agreement with the simulations. Furthermore, the RCS reduction characteristics of the proposed concave structure at different azimuth angles are also evaluated. Numerical calculations and experiments show that the wide-angle RCS reduction from 0° to 34° is achieved. To the best of the information we have, this is the first time that the chessboard metasurfaces, which consist of several polarizing reflectors, have been employed to obtain broadband and wide-angle RCS reduction for the concave structure. This technique validates the novelty and effectiveness of wide-angle and ultra-wideband RCS reduction of the concave structure.
{"title":"Ultra-wideband and wide-angle RCS reduction of a concave structure based on a chessboard polarization conversion metasurfaces","authors":"qingting he, Haiyan Chen, Qian Liu, Xin Yao, Fengxia Li, Liang Difei, Jianliang Xie, Longjiang Deng","doi":"10.1088/1361-6463/ad005e","DOIUrl":"https://doi.org/10.1088/1361-6463/ad005e","url":null,"abstract":"Abstract In this paper, ultra-wideband and wide-angle radar cross section (RCS) reduction of a concave structure is designed and realized based on a chessboard polarization conversion metasurface (CPCM), employing an ultra-wideband polarization conversion metasurface (PCM) composed of a single layer of square split-ring resonators. The concave structure, which is equivalent to an octagonal-like prism, is divided into eight regions. To achieve perfect phase cancellation in the non-central region, it can be equivalent to oblique incidence when the central region is under normal incidence, and phase compensation of the unit cell of metasurfaces in the non-central region is considered. The simulated results demonstrate that the RCS reduction of the proposed concave structure is less than -10 dB in the frequency ranges of 8.8 GHz to 35.75 GHz with fractional bandwidths of 120.99% and exceeds -30 dB at numerous resonant frequencies such as 9.52 GHz, 13.89 GHz, 23.45 GHz, and 35.2 GHz under normal incidence. The experimental results are in good agreement with the simulations. Furthermore, the RCS reduction characteristics of the proposed concave structure at different azimuth angles are also evaluated. Numerical calculations and experiments show that the wide-angle RCS reduction from 0° to 34° is achieved. To the best of the information we have, this is the first time that the chessboard metasurfaces, which consist of several polarizing reflectors, have been employed to obtain broadband and wide-angle RCS reduction for the concave structure. This technique validates the novelty and effectiveness of wide-angle and ultra-wideband RCS reduction of the concave structure.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"97 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study introduces a ferromagnetic material-doped hybrid stereo metamaterial absorber (HSMA) that has been developed to overcome the limitations in broadband absorption of electromagnetic wave. This metamaterial combines a ferromagnetic block with a blind via in the center and a standing resistive trapezoidal patch together in a stereo meta-atom to enable a continuous and broad absorption band for 90% absorptivity from 2.3 GHz to 40 GHz, with a thickness only as 0.079 times the maximum working wavelength. The hybrid absorber also exhibits angular stability under oblique incidence and polarization insensitivity. Furthermore, a sample of proposed HSMA was fabricated and measured. The broadband absorption properties of such hybrid stereo metamaterial were validated by both simulated and experimental results. Our study provides a promising implementation approach for broadband and low-profile microwave absorbers.
{"title":"A broadband low-profile microwave absorber based on ferromagnetic material doped hybrid stereo metamaterial","authors":"Xuyao Wei, Jiajia Wang, Fangkun Zhou, Ruiyang Tan, Jun Liu, Ping Chen","doi":"10.1088/1361-6463/acfaad","DOIUrl":"https://doi.org/10.1088/1361-6463/acfaad","url":null,"abstract":"This study introduces a ferromagnetic material-doped hybrid stereo metamaterial absorber (HSMA) that has been developed to overcome the limitations in broadband absorption of electromagnetic wave. This metamaterial combines a ferromagnetic block with a blind via in the center and a standing resistive trapezoidal patch together in a stereo meta-atom to enable a continuous and broad absorption band for 90% absorptivity from 2.3 GHz to 40 GHz, with a thickness only as 0.079 times the maximum working wavelength. The hybrid absorber also exhibits angular stability under oblique incidence and polarization insensitivity. Furthermore, a sample of proposed HSMA was fabricated and measured. The broadband absorption properties of such hybrid stereo metamaterial were validated by both simulated and experimental results. Our study provides a promising implementation approach for broadband and low-profile microwave absorbers.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134947895","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-04DOI: 10.1088/1361-6463/acfdb7
Mary Ramoy, Naoki Shirai, Koichi Sasaki
Abstract Atmospheric-pressure plasma, generated using a dc power supply, in contact with water was investigated as a green, catalyst-free method for the ammonia synthesis. Stable nitrogen plasmas were generated inside bubbles which were obtained by inserting a dielectric tube with the gas flow into water. A higher production rate was obtained at a higher discharge current, a higher flow rate of nitrogen, and a lower conductivity of water. In addition, the production rate when the water worked as the cathode of the discharge was higher than that with the inverted polarity of the dc power supply. The maximum production rate of ∼0.98 µ mol min −1 was realized at the optimized discharge condition, which is higher than the literature value obtained using a dc discharge in contact with water (Hawtof et al 2019 Sci. Adv. 5 eaat5778). We also discussed the possible reaction fields for the ammonia synthesis in the experimental condition.
摘要:研究了常压等离子体与水接触的绿色、无催化剂合成氨方法。在气泡内产生稳定的氮等离子体，该气泡是通过将介质管插入气体流中而获得的。在较高的放电电流、较高的氮流量和较低的水电导率下，可以获得较高的产量。此外，水作为放电阴极时的产率高于直流电源极性反转时的产率。在优化的放电条件下，最大产率为~ 0.98µmol min - 1，高于文献中使用与水接触的直流放电获得的值(Hawtof et al . 2019 Sci.)。Adv. 5 eaat5778)。讨论了在实验条件下氨合成的可能反应场。
{"title":"Catalyst-free synthesis of ammonia using dc-driven atmospheric-pressure plasma in contact with water","authors":"Mary Ramoy, Naoki Shirai, Koichi Sasaki","doi":"10.1088/1361-6463/acfdb7","DOIUrl":"https://doi.org/10.1088/1361-6463/acfdb7","url":null,"abstract":"Abstract Atmospheric-pressure plasma, generated using a dc power supply, in contact with water was investigated as a green, catalyst-free method for the ammonia synthesis. Stable nitrogen plasmas were generated inside bubbles which were obtained by inserting a dielectric tube with the gas flow into water. A higher production rate was obtained at a higher discharge current, a higher flow rate of nitrogen, and a lower conductivity of water. In addition, the production rate when the water worked as the cathode of the discharge was higher than that with the inverted polarity of the dc power supply. The maximum production rate of ∼0.98 µ mol min −1 was realized at the optimized discharge condition, which is higher than the literature value obtained using a dc discharge in contact with water (Hawtof et al 2019 Sci. Adv. 5 eaat5778). We also discussed the possible reaction fields for the ammonia synthesis in the experimental condition.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135547536","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-10-03DOI: 10.1088/1361-6463/acfa0d
Asif Iqbal, Brian Zahler Bentz, Yang Zhou, Kevin Youngman, Peng Zhang
Abstract This article characterises the effects of cathode photoemission leading to electrical discharges in an argon gas. We perform breakdown experiments under pulsed laser illumination of a flat cathode and observe Townsend to glow discharge transitions. The breakdown process is recorded by high-speed imaging, and time-dependent voltage and current across the electrode gap are measured for different reduced electric fields and laser intensities. We employ a 0D transient discharge model to interpret the experimental measurements. The fitted values of transferred photoelectron charge are compared with calculations from a quantum model of photoemission. The breakdown voltage is found to be lower with photoemission than without. When the applied voltage is insufficient for ion-induced secondary electron emission to sustain the plasma, laser driven photoemission can still create a breakdown where a sheath (i.e. a region near the electrode surfaces consisting of positive ions and neutrals) is formed. This photoemission induced plasma persists and decays on a much longer time scale ( ∼10sμ s) than the laser pulse length ( 30 ps). The effects of different applied voltages and laser energies on the breakdown voltage and current waveforms are investigated. The discharge model can accurately predict the measured breakdown voltage curves, despite the existence of discrepancy in quantitatively describing the transient discharge current and voltage waveforms.
摘要本文研究了氩气中阴极光电致放电效应。我们在脉冲激光照射下进行了平面阴极的击穿实验，观察了汤森德到辉光放电的转变。高速成像记录了击穿过程，并测量了不同电场和激光强度下电极间隙上随时间变化的电压和电流。我们采用了一个0D瞬态放电模型来解释实验测量结果。将转移的光电子电荷的拟合值与光电量子模型的计算结果进行了比较。发现有光电发射的击穿电压比没有光电发射的击穿电压低。当施加的电压不足以使离子诱导的二次电子发射维持等离子体时，激光驱动的光发射仍然可以在形成鞘层(即由正离子和中性离子组成的电极表面附近的区域)的地方产生击穿。这种光发射诱导等离子体在比激光脉冲长度(30 ps)更长的时间尺度(~ 10 s μ s)上持续和衰减。研究了不同外加电压和激光能量对击穿电压和击穿电流波形的影响。尽管在定量描述瞬态放电电流和电压波形方面存在差异，但该放电模型能够准确地预测实测击穿电压曲线。
{"title":"Pulsed photoemission induced plasma breakdown","authors":"Asif Iqbal, Brian Zahler Bentz, Yang Zhou, Kevin Youngman, Peng Zhang","doi":"10.1088/1361-6463/acfa0d","DOIUrl":"https://doi.org/10.1088/1361-6463/acfa0d","url":null,"abstract":"Abstract This article characterises the effects of cathode photoemission leading to electrical discharges in an argon gas. We perform breakdown experiments under pulsed laser illumination of a flat cathode and observe Townsend to glow discharge transitions. The breakdown process is recorded by high-speed imaging, and time-dependent voltage and current across the electrode gap are measured for different reduced electric fields and laser intensities. We employ a 0D transient discharge model to interpret the experimental measurements. The fitted values of transferred photoelectron charge are compared with calculations from a quantum model of photoemission. The breakdown voltage is found to be lower with photoemission than without. When the applied voltage is insufficient for ion-induced secondary electron emission to sustain the plasma, laser driven photoemission can still create a breakdown where a sheath (i.e. a region near the electrode surfaces consisting of positive ions and neutrals) is formed. This photoemission induced plasma persists and decays on a much longer time scale ( <?CDATA $sim!!!10s$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mo>∼</mml:mo> <mml:mn>10</mml:mn> <mml:mi>s</mml:mi> </mml:math> <?CDATA $mu $?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mi>μ</mml:mi> </mml:math> s) than the laser pulse length ( <?CDATA $30$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mn>30</mml:mn> </mml:math> ps). The effects of different applied voltages and laser energies on the breakdown voltage and current waveforms are investigated. The discharge model can accurately predict the measured breakdown voltage curves, despite the existence of discrepancy in quantitatively describing the transient discharge current and voltage waveforms.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135647976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract To improve the interruption capacity of a current-limiting fuse, a detailed diagnosis of the spatial electrical conductivity distribution inside the fuse arc under the current limiting phase around current zero is required, because this distribution determines the distribution of transient recovery voltage inside the fuse. However, well-established methodologies applicable to fuse arcs are lacking, so the spatial distribution remains unknown. This study presents a borescope-integrated spectroscopic system that simultaneously obtains single-shot recordings of the axial distributions of the electron density and arc temperature in the fuse arc just before extinction. Combining the electron densities and arc temperatures, we can identify the fuse arc composition and hence calculate the axial electrical conductivity distribution under the first Chapman–Enskog approximation. The electrical conductivity provided by this systematic methodology includes no large uncertainties, thus demonstrating its superiority against previous estimation methods of the electrical conductivity.
{"title":"Spatiotemporal Evolution of Electrical Conductivity in Current-Limiting-Fuse Arc","authors":"Yuki Inada, Yusuke Fukai, Naoki Takayasu, Yusuke Nakano, Shungo Zen, Wataru Ohnishi, Yasushi Yamano, Mitsuaki Maeyama, Naoto Kodama","doi":"10.1088/1361-6463/acf9b2","DOIUrl":"https://doi.org/10.1088/1361-6463/acf9b2","url":null,"abstract":"Abstract To improve the interruption capacity of a current-limiting fuse, a detailed diagnosis of the spatial electrical conductivity distribution inside the fuse arc under the current limiting phase around current zero is required, because this distribution determines the distribution of transient recovery voltage inside the fuse. However, well-established methodologies applicable to fuse arcs are lacking, so the spatial distribution remains unknown. This study presents a borescope-integrated spectroscopic system that simultaneously obtains single-shot recordings of the axial distributions of the electron density and arc temperature in the fuse arc just before extinction. Combining the electron densities and arc temperatures, we can identify the fuse arc composition and hence calculate the axial electrical conductivity distribution under the first Chapman–Enskog approximation. The electrical conductivity provided by this systematic methodology includes no large uncertainties, thus demonstrating its superiority against previous estimation methods of the electrical conductivity.","PeriodicalId":16833,"journal":{"name":"Journal of Physics D","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135648107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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