Li Gao-Fang, Yin Wen, Huang Jing-Guo, Cui Hao-Yang, Ye Han-Jing, Gao Yan-Qing, Huang Zhi-Ming, Chu Jun-hao
In this paper, the conductivity of intrinsic GaSe, S doped 2.5 mass% GaSe, and S doped 7 mass% GaSe crystals, in the range of 0.3-2.5 THz, was measured by transmission terahertz time-domain spectroscopy, and fitted well with Drude-Smith-Lorentz model which was introduced lattice vibration effect. It was found that the real part of conductivity decreased with S doping, which was caused by the gradual shift of the Fermi energy level of GaSe crystals to the charge neutrality level due to the generation of substitution impurities and gap impurities by S doping, resulting in the reduction of carrier concentration. The intrinsic GaSe and S doping 2.5 mass% GaSe had a clear lattice vibration peak at about 0.56 THz, while GaSe: S 7% had no lattice vibration peak near 0.56 THz, which was mainly due to the S doping increased the structural hardness of the crystal and reduced the interlayer rigidity vibration of the crystal. All three samples had obvious narrow lattice vibration peaks at about 1.81 THz, and the intensity first decreased and then increased with S doping, which mainly due to a small amount of S doping reduced the local structural defects of GaSe and weakened the intensity of the narrow lattice vibration peak, while excessive S doping generated β-type GaS crystals, increased the local structural defects of the crystals and the intensity of the narrow lattice vibration peak. With the increase of S doping, the intensity of the broad lattice vibration peak of GaSe crystal weakened or even disappeared at about 1.07 THz and 2.28 THz, mainly due to the S doping resulting in S substitution impurities and GaS gap impurities, which reducing the fundamental frequency phonon vibration intensity, thereby weakening the lattice vibration caused by the second-order phonon difference mode of the crystal. The results show that the appropriate concentration of S doping can effectively suppress the lattice vibration of GaSe crystal, reduce the conductivity and power loss in the THz band. This study provides important data support and theoretical basis for the design and fabrication of low loss THz devices.
{"title":"Conductivity in sulfur doped gallium selenide crystals measured by terahertz time-domain spectroscopy","authors":"Li Gao-Fang, Yin Wen, Huang Jing-Guo, Cui Hao-Yang, Ye Han-Jing, Gao Yan-Qing, Huang Zhi-Ming, Chu Jun-hao","doi":"10.7498/aps.72.20221548","DOIUrl":"https://doi.org/10.7498/aps.72.20221548","url":null,"abstract":"In this paper, the conductivity of intrinsic GaSe, S doped 2.5 mass% GaSe, and S doped 7 mass% GaSe crystals, in the range of 0.3-2.5 THz, was measured by transmission terahertz time-domain spectroscopy, and fitted well with Drude-Smith-Lorentz model which was introduced lattice vibration effect. It was found that the real part of conductivity decreased with S doping, which was caused by the gradual shift of the Fermi energy level of GaSe crystals to the charge neutrality level due to the generation of substitution impurities and gap impurities by S doping, resulting in the reduction of carrier concentration. The intrinsic GaSe and S doping 2.5 mass% GaSe had a clear lattice vibration peak at about 0.56 THz, while GaSe: S 7% had no lattice vibration peak near 0.56 THz, which was mainly due to the S doping increased the structural hardness of the crystal and reduced the interlayer rigidity vibration of the crystal. All three samples had obvious narrow lattice vibration peaks at about 1.81 THz, and the intensity first decreased and then increased with S doping, which mainly due to a small amount of S doping reduced the local structural defects of GaSe and weakened the intensity of the narrow lattice vibration peak, while excessive S doping generated β-type GaS crystals, increased the local structural defects of the crystals and the intensity of the narrow lattice vibration peak. With the increase of S doping, the intensity of the broad lattice vibration peak of GaSe crystal weakened or even disappeared at about 1.07 THz and 2.28 THz, mainly due to the S doping resulting in S substitution impurities and GaS gap impurities, which reducing the fundamental frequency phonon vibration intensity, thereby weakening the lattice vibration caused by the second-order phonon difference mode of the crystal. The results show that the appropriate concentration of S doping can effectively suppress the lattice vibration of GaSe crystal, reduce the conductivity and power loss in the THz band. This study provides important data support and theoretical basis for the design and fabrication of low loss THz devices.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"22 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82233700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luo Yu-Xuan, Cheng Yong-Zhi, Chen Fu, Luo Hui, Li Xiang-Cheng
In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. Firstly, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49-2.40 GHz) and 15.1% (2.98-3.63 GHz), respectively, which can achieve more than -40 dB rejection in the range of 4.77-7.48 GHz. The upper and lower cutoff frequencies of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a deeper understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in microwave integrated circuit applications.
{"title":"Dual-band filter design based on hourglass-shaped spoof surface plasmon polaritons and interdigital capacitor structure","authors":"Luo Yu-Xuan, Cheng Yong-Zhi, Chen Fu, Luo Hui, Li Xiang-Cheng","doi":"10.7498/aps.72.20221984","DOIUrl":"https://doi.org/10.7498/aps.72.20221984","url":null,"abstract":"In this paper, a dual passband filter with spoof surface plasmon polaritons (SSPPs) and interdigital capacitance structure loaded on a coplanar waveguide (CPW) is proposed. Firstly, the hourglass-shaped SSPP unit-cell structure and the interdigital capacitor structure are introduced on the coplanar waveguide transmission line to obtain high fractional bandwidth and low insertion loss passband characteristics. Then, a dual passband filter is formed by loading the interdigital capacitor loop resonator to excite the trapped waves. The simulation results show that the proposed dual passband filter has excellent upper sideband rejection and dual passband filtering performance. The fractional bandwidths of the two passbands of the design are 46.8% (1.49-2.40 GHz) and 15.1% (2.98-3.63 GHz), respectively, which can achieve more than -40 dB rejection in the range of 4.77-7.48 GHz. The upper and lower cutoff frequencies of the two passbands can be independently regulated by changing the structural parameters of the proposed filter. In order to gain a deeper understanding of the operating principle of the dual passband filter, the corresponding dispersion curves and electric field distribution, LC equivalent circuit analysis are given. Finally, the prototype of the designed filter is fabricated according to the optimized parameter values. The experimental results are in good agreement with the simulation ones, indicating that the proposed dual-passband filter is of great importance in microwave integrated circuit applications.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"51 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87867105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Liu Huizhen, Liu Bei, Dong Jiabin, Li Jianpeng, Cao Zixiu, Liu Yue, Meng Rutao, Zhang Yi
Efficient copper based thin film solar cells usually use inorganic n-type semiconductor material CdS as the buffer layer. Therefore, the interface quality and energy band matching between the buffer layer and the absorption layer are crucial to the collection and utilization of carriers. Heat treatment can promote the mutual diffusion of interface elements, the migration of ions in the material and the change of defect state, and the proper temperature will change the degree of Cu-Zn ordering in the absorption layer, so as to improve the efficiency of the solar cells. Based on the optimization of CdS basic process, the strategy of annealing CdS/copper-based thin film heterojunction in sulfur atmosphere further improves the quality of CdS thin film, and applies it to copper-based solar cells to regulate the p-n heterojunction energy band gap matching of copper-based thin film cells. The results show that the annealing of CdS film in sulfur-containing inert atmosphere can effectively improve the crystal quality of CdS film and inhibit the non-radiative recombination loss caused by defect trapping at the interface of CZTS/CdS heterojunction, and the open-circuit voltage of the device can be significantly increased, up to 718 mV. In addition, annealing CZTS/CdS heterojunction in S/Ar atmosphere can effectively improve the p-n heterojunction energy band gap matching, which not only improves the electron transmission, but also reduces the carrier recombination, thus improving the Voc and FF of devices. Besides, the oxygen element in CdS film can be replaced by sulfur element in sulfur atmosphere to improve the quality of CdS film and thus enhance the short-wave absorption of solar cell devices. Therefore, In terms of device efficiency, the efficiency of CZTS solar cell based on sputtering method has increased from 3.47% to 5.68%, which is about twice that of non-annealing treatment, Its device structure is Glass/Mo/CZTS/CdS/i-ZnO/Al:ZnO/Ni/Al, providing a reliable process window for copper based thin film solar cell devices to achieve high open-circuit voltage. Meanwhile, this study strongly demonstrates the importance of annealing atmosphere selection for CdS quality and energy band matching of CZTS/CdS heterojunction. In addition to interface interdiffusion, the composition and crystallinity of thin film materials are controlled.
{"title":"Study on the regulation of solar cell performance by cadmium sulfide/copper-based thin film heterojunction annealing under different atmospheres","authors":"Liu Huizhen, Liu Bei, Dong Jiabin, Li Jianpeng, Cao Zixiu, Liu Yue, Meng Rutao, Zhang Yi","doi":"10.7498/aps.72.20230105","DOIUrl":"https://doi.org/10.7498/aps.72.20230105","url":null,"abstract":"Efficient copper based thin film solar cells usually use inorganic n-type semiconductor material CdS as the buffer layer. Therefore, the interface quality and energy band matching between the buffer layer and the absorption layer are crucial to the collection and utilization of carriers. Heat treatment can promote the mutual diffusion of interface elements, the migration of ions in the material and the change of defect state, and the proper temperature will change the degree of Cu-Zn ordering in the absorption layer, so as to improve the efficiency of the solar cells. Based on the optimization of CdS basic process, the strategy of annealing CdS/copper-based thin film heterojunction in sulfur atmosphere further improves the quality of CdS thin film, and applies it to copper-based solar cells to regulate the p-n heterojunction energy band gap matching of copper-based thin film cells. The results show that the annealing of CdS film in sulfur-containing inert atmosphere can effectively improve the crystal quality of CdS film and inhibit the non-radiative recombination loss caused by defect trapping at the interface of CZTS/CdS heterojunction, and the open-circuit voltage of the device can be significantly increased, up to 718 mV. In addition, annealing CZTS/CdS heterojunction in S/Ar atmosphere can effectively improve the p-n heterojunction energy band gap matching, which not only improves the electron transmission, but also reduces the carrier recombination, thus improving the Voc and FF of devices. Besides, the oxygen element in CdS film can be replaced by sulfur element in sulfur atmosphere to improve the quality of CdS film and thus enhance the short-wave absorption of solar cell devices. Therefore, In terms of device efficiency, the efficiency of CZTS solar cell based on sputtering method has increased from 3.47% to 5.68%, which is about twice that of non-annealing treatment, Its device structure is Glass/Mo/CZTS/CdS/i-ZnO/Al:ZnO/Ni/Al, providing a reliable process window for copper based thin film solar cell devices to achieve high open-circuit voltage. Meanwhile, this study strongly demonstrates the importance of annealing atmosphere selection for CdS quality and energy band matching of CZTS/CdS heterojunction. In addition to interface interdiffusion, the composition and crystallinity of thin film materials are controlled.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"106 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88107704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tao Chen-Yu, Lei Jian-Ting, Yu Xuan, Luo Yan, Ma Xin-wen, Zhang Shao-Feng
In the past two decades,the development of laser technology has made attosecond science become a cutting-edge research field,providing various novel perspectives for the study of quantum few-body ultrafast evolution.The attosecond pulses prepared in the current laboratory are widely used in experimental research in the form of isolated pulses or pulse trains.The ultrafast changing light field allows people to control and track the motion of electrons at the atomic-scale,and realizes real-time tracking of electron dynamics on the sub-femtosecond time-scale.This review focuses on the progress in the study of ultrafast dynamics of atoms and molecules,which is an important part of attosecond science.Firstly,the generation and development of attosecond pulses are reviewed,mainly including the principle of high-order harmonic and the separation method of single-attosecond pulses.Then the applications of attosecond pulses are systematically introduced,including photo-ionization time delay,attosecond charge migration,non-adiabatic molecular dynamics and so on.Finally,the summary and outlook of the application of attosecond pulses are presented.
{"title":"Development of Attosecond Pulse and Application in Ultrafast Dynamics of Atoms and Molecules","authors":"Tao Chen-Yu, Lei Jian-Ting, Yu Xuan, Luo Yan, Ma Xin-wen, Zhang Shao-Feng","doi":"10.7498/aps.72.20222436","DOIUrl":"https://doi.org/10.7498/aps.72.20222436","url":null,"abstract":"In the past two decades,the development of laser technology has made attosecond science become a cutting-edge research field,providing various novel perspectives for the study of quantum few-body ultrafast evolution.The attosecond pulses prepared in the current laboratory are widely used in experimental research in the form of isolated pulses or pulse trains.The ultrafast changing light field allows people to control and track the motion of electrons at the atomic-scale,and realizes real-time tracking of electron dynamics on the sub-femtosecond time-scale.This review focuses on the progress in the study of ultrafast dynamics of atoms and molecules,which is an important part of attosecond science.Firstly,the generation and development of attosecond pulses are reviewed,mainly including the principle of high-order harmonic and the separation method of single-attosecond pulses.Then the applications of attosecond pulses are systematically introduced,including photo-ionization time delay,attosecond charge migration,non-adiabatic molecular dynamics and so on.Finally,the summary and outlook of the application of attosecond pulses are presented.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"7 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88169816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Membrane has widely applications in the field of filtration and separation, but due to the attraction or repulsion exerted by the membrane, the particles will experience directional motion. As a result, two totally opposite effects, particle enrichment and exclusion zone, take place in the vicinity of the membrane, and the underlying reason is still not clear. In the paper, colloidal particles with negative surface charge was used as a model substance, with the advantages of monitoring the particles concentration in a real time and in situ way, to investigate the influence of cellulose membrane to the movement of particles. The experimental results showed that particles enriched in the vicinity of the membrane. The diffusiophoresis effect originates from the tiny amount ions released by the film is the main reason of the directional movement of the charged particles. Based on the two mechanisms of diffusiophoresis and diffusion, we construct a model and make relevant numerical calculation, and the numerical results are qualitatively consistent with the experimental results. Moreover, in addition to the longitudinal motion of the particles towards the filter membrane, diffusio-osmotic flow and particles lateral diffusion also result in the migration of particles towards to the container wall, and further increase particles number near the wall.
{"title":"DIRECTIONAL MOTION OF CHARGED PARTICLES NEAR MEMBRANE","authors":"Zhou Hongwei, Ouyang Wenze, Xu Shenghua","doi":"10.7498/aps.72.20220567","DOIUrl":"https://doi.org/10.7498/aps.72.20220567","url":null,"abstract":"Membrane has widely applications in the field of filtration and separation, but due to the attraction or repulsion exerted by the membrane, the particles will experience directional motion. As a result, two totally opposite effects, particle enrichment and exclusion zone, take place in the vicinity of the membrane, and the underlying reason is still not clear. In the paper, colloidal particles with negative surface charge was used as a model substance, with the advantages of monitoring the particles concentration in a real time and in situ way, to investigate the influence of cellulose membrane to the movement of particles. The experimental results showed that particles enriched in the vicinity of the membrane. The diffusiophoresis effect originates from the tiny amount ions released by the film is the main reason of the directional movement of the charged particles. Based on the two mechanisms of diffusiophoresis and diffusion, we construct a model and make relevant numerical calculation, and the numerical results are qualitatively consistent with the experimental results. Moreover, in addition to the longitudinal motion of the particles towards the filter membrane, diffusio-osmotic flow and particles lateral diffusion also result in the migration of particles towards to the container wall, and further increase particles number near the wall.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91316303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chen Chuan-Sheng, Ding Shuai, Han Xu, Wang Bing-Zhong
Achieving tunable focus of electromagnetic field energy at multiple target points is a critical challenge in the wireless power transfer (WPT) domain. Although techniques such as optimal constrained power focusing (OCPF) and time reversal (TR) have been proposed. The former presents limited practical applicability while the latter is noteworthy for its adaptive spatio-temporal synchronous focusing characteristics. However, the time reversal mirror (TRM) method necessitates intricate pretesting and has highly complex systems. In this study, we introduce a novel channel processing method, named channel extraction, selection, weighting, and reconstruction (CESWR), to attain balanced power distribution for multiple users, characterized by low complexity, high computability, and rapid convergence. Diverging from the traditional TR approach, our proposed method, grounded in channel correlation considerations, filters the channel impulse response (CIR) for multiple targets, segregating them into distinct characteristic and similar components for each target. This method ensures focused generation at both receiving ends while facilitating high-precision regulation of the peak voltage of the received signal. Furthermore, this study embarks on a rigorous examination of the linearity intrinsic to the proposed methodology, explicating a singular correspondence between the tuning of theoretical weights and the resultant outcomes. In order to authenticate the efficacy of this methodology, we construct a single-input multiple-output time-reversal cavity (SIMO-TRC) system for the experimental section of this manuscript. Subsequent experimentation, conducted for both loosely and tightly correlated models, furnishes invaluable insights. Evidently, in the loosely correlated model, the CESWR method exhibits proficiency in attaining a peak voltage ratio (PVR) of nearly 1.00 at the two receivers, with a minuscule numerical discrepancy of merely 8×10-6 mV. In stark contrast, under the tightly correlated model, the CESWR method demonstrates an enhanced ability to differentiate between two targets, thus offering a noticeable improvement over the classic single-target TR method.
{"title":"Channel processing-based time-reversal method for multi-target tunable focusing","authors":"Chen Chuan-Sheng, Ding Shuai, Han Xu, Wang Bing-Zhong","doi":"10.7498/aps.72.20230547","DOIUrl":"https://doi.org/10.7498/aps.72.20230547","url":null,"abstract":"Achieving tunable focus of electromagnetic field energy at multiple target points is a critical challenge in the wireless power transfer (WPT) domain. Although techniques such as optimal constrained power focusing (OCPF) and time reversal (TR) have been proposed. The former presents limited practical applicability while the latter is noteworthy for its adaptive spatio-temporal synchronous focusing characteristics. However, the time reversal mirror (TRM) method necessitates intricate pretesting and has highly complex systems. In this study, we introduce a novel channel processing method, named channel extraction, selection, weighting, and reconstruction (CESWR), to attain balanced power distribution for multiple users, characterized by low complexity, high computability, and rapid convergence. Diverging from the traditional TR approach, our proposed method, grounded in channel correlation considerations, filters the channel impulse response (CIR) for multiple targets, segregating them into distinct characteristic and similar components for each target. This method ensures focused generation at both receiving ends while facilitating high-precision regulation of the peak voltage of the received signal. Furthermore, this study embarks on a rigorous examination of the linearity intrinsic to the proposed methodology, explicating a singular correspondence between the tuning of theoretical weights and the resultant outcomes. In order to authenticate the efficacy of this methodology, we construct a single-input multiple-output time-reversal cavity (SIMO-TRC) system for the experimental section of this manuscript. Subsequent experimentation, conducted for both loosely and tightly correlated models, furnishes invaluable insights. Evidently, in the loosely correlated model, the CESWR method exhibits proficiency in attaining a peak voltage ratio (PVR) of nearly 1.00 at the two receivers, with a minuscule numerical discrepancy of merely 8×10-6 mV. In stark contrast, under the tightly correlated model, the CESWR method demonstrates an enhanced ability to differentiate between two targets, thus offering a noticeable improvement over the classic single-target TR method.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"18 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91294217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microwave Thermoacoustic Imaging (MTAI) is an exciting imaging technique rooted in the underlying principle of exploiting the distinct electrical properties of biological tissues. By harnessing short-pulsed microwaves as a stimulation source and leveraging their interaction with the human body, MTAI has paved the way for revolutionary advancements in medical imaging. When microwaves are absorbed by polar molecules and ions within the tissues, an ingenious thermoelastic effect gives rise to ultrasound waves. These ultrasound waves, brimming with invaluable pathological and physiological insights, propagate outward, carrying the essence of the biological tissue's composition and functionality. Through a meticulous collection of ultrasound signals from all directions surrounding the tissue, it becomes possible to reconstruct intricate internal structures and visualize the tissue's functional dynamics. MTAI excels in non-invasiveness, capable of delving several centimeters beneath the surface with a microscopic resolution on the order of micrometers. The magic lies in the transformative conversion of microwave energy into ultrasound waves, tapping into the tissue's hidden depths without causing harm. This groundbreaking imaging modality unlocks a realm of possibilities for acquiring profound insights into the intricate structures and functionality of deep-seated tissues. Furthermore, the inherent polarization characteristics of microwaves empower MTAI to capture additional dimensions of information, unraveling the intricate polarization properties and illuminating a richer understanding of the tissue's complexity. The immense potential of MTAI extends far and wide within the realm of medicine. It has already demonstrated remarkable achievements in non-invasively imaging brain structures, screening for breast tumors, visualizing arthritis in human joints, and detecting liver fat content. These accomplishments have laid a solid foundation, firmly establishing MTAI as a trailblazing medical imaging technique. This article offers a comprehensive and in-depth exploration of the physical principles underpinning MTAI, the sophisticated system devices involved, and the recent groundbreaking research breakthroughs. Moreover, it delves into the exciting prospects and challenges that lie ahead in the future development of MTAI. As the technology continues to progress by leaps and bounds, MTAI is poised to shatter barriers, ushering in a new era of unrivaled imaging quality and performance. This, in turn, will open the floodgates for transformative innovation and application in the realms of medical diagnosis and treatment. The anticipation is palpable as MTAI strives to make substantial contributions to the ever-evolving field of medical imaging, bestowing upon humanity more precise, reliable, and life-enhancing diagnostic capabilities.
{"title":"Biomedical Microwave-induced Thermoacoustic Imaging","authors":"Yu Wang, Huiming Zhang, Huan Qin","doi":"10.7498/aps.72.20230732","DOIUrl":"https://doi.org/10.7498/aps.72.20230732","url":null,"abstract":"Microwave Thermoacoustic Imaging (MTAI) is an exciting imaging technique rooted in the underlying principle of exploiting the distinct electrical properties of biological tissues. By harnessing short-pulsed microwaves as a stimulation source and leveraging their interaction with the human body, MTAI has paved the way for revolutionary advancements in medical imaging. When microwaves are absorbed by polar molecules and ions within the tissues, an ingenious thermoelastic effect gives rise to ultrasound waves. These ultrasound waves, brimming with invaluable pathological and physiological insights, propagate outward, carrying the essence of the biological tissue's composition and functionality. Through a meticulous collection of ultrasound signals from all directions surrounding the tissue, it becomes possible to reconstruct intricate internal structures and visualize the tissue's functional dynamics. MTAI excels in non-invasiveness, capable of delving several centimeters beneath the surface with a microscopic resolution on the order of micrometers. The magic lies in the transformative conversion of microwave energy into ultrasound waves, tapping into the tissue's hidden depths without causing harm. This groundbreaking imaging modality unlocks a realm of possibilities for acquiring profound insights into the intricate structures and functionality of deep-seated tissues. Furthermore, the inherent polarization characteristics of microwaves empower MTAI to capture additional dimensions of information, unraveling the intricate polarization properties and illuminating a richer understanding of the tissue's complexity. The immense potential of MTAI extends far and wide within the realm of medicine. It has already demonstrated remarkable achievements in non-invasively imaging brain structures, screening for breast tumors, visualizing arthritis in human joints, and detecting liver fat content. These accomplishments have laid a solid foundation, firmly establishing MTAI as a trailblazing medical imaging technique. This article offers a comprehensive and in-depth exploration of the physical principles underpinning MTAI, the sophisticated system devices involved, and the recent groundbreaking research breakthroughs. Moreover, it delves into the exciting prospects and challenges that lie ahead in the future development of MTAI. As the technology continues to progress by leaps and bounds, MTAI is poised to shatter barriers, ushering in a new era of unrivaled imaging quality and performance. This, in turn, will open the floodgates for transformative innovation and application in the realms of medical diagnosis and treatment. The anticipation is palpable as MTAI strives to make substantial contributions to the ever-evolving field of medical imaging, bestowing upon humanity more precise, reliable, and life-enhancing diagnostic capabilities.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"11 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91237546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dan Min, 金凡亚, Chen Lun-Jiang, He Yan-Bin, Wan Jun-Hao, Zhang Hong, Zhang Ke-Jia, Yang Yin, Jin Fan-Ya
In order to further improve the superconducting current carrying capacity of REBCO coated conductor under strong magnetic field, ion irradiation is used to generate the pinning center of introduced magnetic flux in the REBCO coated conductor. In this paper, the H-ion irradiation of REBCO second generation high temperature superconductor strip was carried out by using the 320kV high charge state ion synthesis research platform. DB-SPBA combined with Raman spectroscopy was used to measure the change of microstructure in YBCO samples irradiated by H+ions within the range of 5.0×1014~1.0×1016. The positron annihilation parameters in YBCO before and after irradiation were analyzed. It is found that after 100 keV H+ion irradiation, a large number of defects including vacancy, vacancy group or dislocation group are produced in the superconducting layer. The larger the irradiation dose, the more vacancy type defects are produced, the more complex the defect types are, and the annihilation mechanism of positrons in the defects changes. Raman spectroscopy results show that with the increase of H+ion irradiation dose, the oxygen atoms in the coating rearrange, the plane spacing increases, the orthogonal phase structure of the coating is destroyed, and the degree of order decreases. The defects produced by such ion irradiation lay a foundation for the introduction of flux pinning centers. Further research can be carried out in combination with X-ray diffractometer, transmission electron microscope, superconductivity and other testing methods to provide theoretical and practical reference for the optimization of material properties.
{"title":"Defect Evolution in Y0.5Gd0.5Ba2Cu3O7-δ Layer by H Ion Irradiation","authors":"Dan Min, 金凡亚, Chen Lun-Jiang, He Yan-Bin, Wan Jun-Hao, Zhang Hong, Zhang Ke-Jia, Yang Yin, Jin Fan-Ya","doi":"10.7498/aps.72.20221612","DOIUrl":"https://doi.org/10.7498/aps.72.20221612","url":null,"abstract":"In order to further improve the superconducting current carrying capacity of REBCO coated conductor under strong magnetic field, ion irradiation is used to generate the pinning center of introduced magnetic flux in the REBCO coated conductor. In this paper, the H-ion irradiation of REBCO second generation high temperature superconductor strip was carried out by using the 320kV high charge state ion synthesis research platform. DB-SPBA combined with Raman spectroscopy was used to measure the change of microstructure in YBCO samples irradiated by H+ions within the range of 5.0×1014~1.0×1016. The positron annihilation parameters in YBCO before and after irradiation were analyzed. It is found that after 100 keV H+ion irradiation, a large number of defects including vacancy, vacancy group or dislocation group are produced in the superconducting layer. The larger the irradiation dose, the more vacancy type defects are produced, the more complex the defect types are, and the annihilation mechanism of positrons in the defects changes. Raman spectroscopy results show that with the increase of H+ion irradiation dose, the oxygen atoms in the coating rearrange, the plane spacing increases, the orthogonal phase structure of the coating is destroyed, and the degree of order decreases. The defects produced by such ion irradiation lay a foundation for the introduction of flux pinning centers. Further research can be carried out in combination with X-ray diffractometer, transmission electron microscope, superconductivity and other testing methods to provide theoretical and practical reference for the optimization of material properties.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"15 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87584065","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Keda Liang, Tengfei Liu, Zhe Chang, Meng Zhang, ZhiXin Li, Songsong Huang, Jing Wang
The propagation speed is one of the important parameters of the internal solitary waves(ISWs). How to obtain the ISWs speed through optical remote sensing images accurately and quickly is an important problem to be solved. In this paper, we simulate ISWs optical remote sensing imaging and obtain an experimental database and build the ISWs speed inversion models based on a single-scene optical remote sensing image by using the least squares method and the support vector machine. The accuracy of the ISW speed inversion models were tested by using MODIS Image and GF-4 image data of the South China Sea. The study results show that: The least squares ISW speed inversion model can give the regression equation, which is more intuitive and has less accuracy in the water depth range from 300 meters to 399 meters, while the support vector machine ISW speed inversion model has high accuracy in the water depth range from 400 meters to 1200 meters and from 83 meters to 299 meters. Therefore, the two kinds of ISW speed inversion models have different advantages, and can be applied to the inversion of the ISW speed in the real ocean.
{"title":"Research on inversion models of internal solitary wave propagation speed in ocean based on least square method and support vector machine","authors":"Keda Liang, Tengfei Liu, Zhe Chang, Meng Zhang, ZhiXin Li, Songsong Huang, Jing Wang","doi":"10.7498/aps.72.20221633","DOIUrl":"https://doi.org/10.7498/aps.72.20221633","url":null,"abstract":"The propagation speed is one of the important parameters of the internal solitary waves(ISWs). How to obtain the ISWs speed through optical remote sensing images accurately and quickly is an important problem to be solved. In this paper, we simulate ISWs optical remote sensing imaging and obtain an experimental database and build the ISWs speed inversion models based on a single-scene optical remote sensing image by using the least squares method and the support vector machine. The accuracy of the ISW speed inversion models were tested by using MODIS Image and GF-4 image data of the South China Sea. The study results show that: The least squares ISW speed inversion model can give the regression equation, which is more intuitive and has less accuracy in the water depth range from 300 meters to 399 meters, while the support vector machine ISW speed inversion model has high accuracy in the water depth range from 400 meters to 1200 meters and from 83 meters to 299 meters. Therefore, the two kinds of ISW speed inversion models have different advantages, and can be applied to the inversion of the ISW speed in the real ocean.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"99 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88415916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Large-size conductive targets or coated targets are difficult issues in computational electromagnetics. In general, such targets can be classified as multi-scale problems. Multi-scale problems usually consume a large number of computational resources. Researchers are devoted to seeking fast methods for these problems. When the skin depth is less than the size of a conductive target, the tangential components of the electric and magnetic fields over the surface of the target can be correlated by the surface impedance Ẑ. Ẑ is usually a complex function of the frequency, and it can be used to formulate an impedance boundary condition (IBC) to describe iterative equations in time domain methods to avoid the volumetric discretization of the target to improve computational efficiency. This condition is commonly known as the surface impedance boundary condition (SIBC). Similarly, for a conductor with thickness on the order or less than the skin depth, it also has high resource requirements if the target is straightforward volumetric discretization. The transmission impedance boundary condition (TIBC) can be applied to replace a coated object to reduce resource requirements. Thus, volumetric discretization is not required. There are few studies on the IBC scheme in the DGTD method. P. Li discussed the IBC scheme in DGTD, which involves complex matrix operations in the processing of IBC. In the DGTD method, numerical flux is used to transmit data between neighboring elements, and the key to the IBC scheme in DGTD is how to handle numerical flux. We hope to propose a DGTD method with a simple form and matrix-free IBC scheme. The key in dealing with IBC in DGTD is numerical flux. Unlike the literature, the impedance ẐR is not approximated by rational functions in our study. A specfic function ẐR obtained after the derivation in this paper is approximated by rational functions in the Laplace domain using the vector-fitting (VF) method, and its time-domain iteration scheme is given. This approach avoids matrix operations. The TIBC and SIBC processing schemes are given in section 4. The proposed method's advantage is that the upwind flux's standard coefficients are retained, and the complex frequency-time conversion problem is implemented by the vector-fitting method. The one-dimensional and three-dimensional examples also show the accuracy and effectiveness of our work in this paper.
{"title":"A simple DGTD method with the impedance boundary condition","authors":"Yang Qian, Wei Bing, Li Linqian, Deng Haochuan","doi":"10.7498/aps.72.20222104","DOIUrl":"https://doi.org/10.7498/aps.72.20222104","url":null,"abstract":"Large-size conductive targets or coated targets are difficult issues in computational electromagnetics. In general, such targets can be classified as multi-scale problems. Multi-scale problems usually consume a large number of computational resources. Researchers are devoted to seeking fast methods for these problems. When the skin depth is less than the size of a conductive target, the tangential components of the electric and magnetic fields over the surface of the target can be correlated by the surface impedance Ẑ. Ẑ is usually a complex function of the frequency, and it can be used to formulate an impedance boundary condition (IBC) to describe iterative equations in time domain methods to avoid the volumetric discretization of the target to improve computational efficiency. This condition is commonly known as the surface impedance boundary condition (SIBC). Similarly, for a conductor with thickness on the order or less than the skin depth, it also has high resource requirements if the target is straightforward volumetric discretization. The transmission impedance boundary condition (TIBC) can be applied to replace a coated object to reduce resource requirements. Thus, volumetric discretization is not required. There are few studies on the IBC scheme in the DGTD method. P. Li discussed the IBC scheme in DGTD, which involves complex matrix operations in the processing of IBC. In the DGTD method, numerical flux is used to transmit data between neighboring elements, and the key to the IBC scheme in DGTD is how to handle numerical flux. We hope to propose a DGTD method with a simple form and matrix-free IBC scheme. The key in dealing with IBC in DGTD is numerical flux. Unlike the literature, the impedance ẐR is not approximated by rational functions in our study. A specfic function ẐR obtained after the derivation in this paper is approximated by rational functions in the Laplace domain using the vector-fitting (VF) method, and its time-domain iteration scheme is given. This approach avoids matrix operations. The TIBC and SIBC processing schemes are given in section 4. The proposed method's advantage is that the upwind flux's standard coefficients are retained, and the complex frequency-time conversion problem is implemented by the vector-fitting method. The one-dimensional and three-dimensional examples also show the accuracy and effectiveness of our work in this paper.","PeriodicalId":6995,"journal":{"name":"物理学报","volume":"1 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88862481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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