Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are ...Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are enhanced when the two circularly polarized lights have comparable intensities.In addition,the curves of ionization rate versus the field amplitude ratio of the two colors for counter-rotating and co-rotating fields coincide with each other in the length gauge case at the total laser intensity 5×10^14 W/cm^2,which agrees with the experimental observation.Moreover,the degree of the coincidence between the ionization rate curves of the two bicircular fields decreases with the increasing field amplitude ratio and decreasing total laser intensity.With the help of the ADK theory,the above characteristics of the ionization rate curves can be well interpreted,which is related to the transition from the tunneling to multiphoton ionization mechanism.展开更多
This paper deals with S-matrix, born first approximation, amplitude, and differential cross-section (DCS), using Volkov function and Taylor series expansion in laser field, scattering. Equation (30) copes-with DCS and...This paper deals with S-matrix, born first approximation, amplitude, and differential cross-section (DCS), using Volkov function and Taylor series expansion in laser field, scattering. Equation (30) copes-with DCS and Equation (36) deals with S-matrix, with different parameters, moreover, both equations contain real and imaginary parts. The DCS increases with increasing angle and polarizabilities, constant with dipole distance for both emission and absorption of single-photon. The DCS for both emission and absorption is responded to low incidence energy (30 eV - 60 eV) and photon energy (15 eV) while at high energy only emission and absorption are responded for DCS. The DCS between absorption and emission of a photon with angle variation, dipole distance, and atomic polarizabilities was found 1.098 a.u.<sup>2</sup> and at high incidence, energies were found 0.1 a.u.<sup>2</sup>.展开更多
研究了单个线性关系是可闭线性关系的充分必要条件;并对L0=(A B C D),其中A,B,C,D是相应Hilbert空间上的线性关系,利用C相对A的有界性与B相对D的有界性及A,D的可闭性,推出了L_(0)也是可闭线性关系;同时,对于有界线性算子S=(S_(1) S_(2) ...研究了单个线性关系是可闭线性关系的充分必要条件;并对L0=(A B C D),其中A,B,C,D是相应Hilbert空间上的线性关系,利用C相对A的有界性与B相对D的有界性及A,D的可闭性,推出了L_(0)也是可闭线性关系;同时,对于有界线性算子S=(S_(1) S_(2) S_(3) S_(4)),得到当满足一定条件时L_(0)-μS的Frobenius-Schur分解公式,并得到了当L_(0)可闭时L_(0)的表达式,最后研究了L_(0)的S-本质谱。展开更多
A program developed with COMSOL software integrates EAST four-strap antenna coupling with the double-stub Ferrite tuners(FT)impedance matching,obtaining physical quantities crucial for predicting the overall performan...A program developed with COMSOL software integrates EAST four-strap antenna coupling with the double-stub Ferrite tuners(FT)impedance matching,obtaining physical quantities crucial for predicting the overall performance of the ion cyclotron resonance heating(ICRH)antenna and matching system.These quantities encompass S-matrix,port complex impedance,reflection coefficients,electric field and voltage distribution,and optimal matching settings.In this study,we explore the relationship between S-matrix,reflection coefficients,port complex impedance,and frequency.Then,we analyze the impact of Faraday screens placement position and transparency,the distance from the Faraday screen(FS)to the current straps(CS),the relative distance between ports,and the characteristic impedance of the transmission line on the coupling characteristic impedance of the EAST ICRH system.Finally,we simulate the electric field distribution and voltage distribution of the EAST ICRH system for plasma heating with double-stub FT impedance matching.Using optimized parameters,the coupling power of the ICRH system can be approximately doubled.The results present herein may offer guidance for the design of high-power,long-pulse operation ICRH antenna systems.展开更多
双模离散傅里叶变换–扩展正交频分复用(discrete fourier transform–spreading-orthogonal frequency division multiplexing-discrete multi,DFT-S-OFDM-DM)系统虽然拥有优秀的峰均功率比(peak to average power ratio,PAPR)、信道...双模离散傅里叶变换–扩展正交频分复用(discrete fourier transform–spreading-orthogonal frequency division multiplexing-discrete multi,DFT-S-OFDM-DM)系统虽然拥有优秀的峰均功率比(peak to average power ratio,PAPR)、信道适应能力以及低复杂度,但此系统在频谱效率(spectral efficiency,SE)表现上并不理想,系统中的离散傅里叶变换(discrete fourier transform,DFT)扩展和双模调制都有一定的改进空间。针对此系统,提出新的多维索引离散傅里叶变换-扩展正交频分复用(discrete fourier transform-spreading-orthogonal frequency division multiplexing-multi dimension index,DFT-S-OFDM-MDI)系统,新系统将DFT扩展改为DFT索引扩展,增加新的子载波索引位,增加双模调制搭配种类,提升双模索引位宽,进而提升系统SE。本文还为新系统配置6种双模星座图,并与预编码增益矩阵搭配,提升系统误码率(bit error ratio,BER)性能。仿真结果表明,系统具有优秀的SE和BER性能,优于多种传统方案。展开更多
基金Project supported by the Key Laboratory Project of Computational Physics of National Defense Science and Technology of China(Grant No.6142A05180401)the National Key Program for S&T Research and Development of China(Grant Nos.2019YFA0307700 and 2016YFA0401100)the National Natural Science Foundation of China(Grant Nos.11847307,11425414,11504215,11774361,and 11874246).
文摘Ionization of atoms in counter-rotating and co-rotating bicircular laser fields is studied using the S-matrix theory in both length and velocity gauges.We show that for both the bicircular fields,ionization rates are enhanced when the two circularly polarized lights have comparable intensities.In addition,the curves of ionization rate versus the field amplitude ratio of the two colors for counter-rotating and co-rotating fields coincide with each other in the length gauge case at the total laser intensity 5×10^14 W/cm^2,which agrees with the experimental observation.Moreover,the degree of the coincidence between the ionization rate curves of the two bicircular fields decreases with the increasing field amplitude ratio and decreasing total laser intensity.With the help of the ADK theory,the above characteristics of the ionization rate curves can be well interpreted,which is related to the transition from the tunneling to multiphoton ionization mechanism.
文摘This paper deals with S-matrix, born first approximation, amplitude, and differential cross-section (DCS), using Volkov function and Taylor series expansion in laser field, scattering. Equation (30) copes-with DCS and Equation (36) deals with S-matrix, with different parameters, moreover, both equations contain real and imaginary parts. The DCS increases with increasing angle and polarizabilities, constant with dipole distance for both emission and absorption of single-photon. The DCS for both emission and absorption is responded to low incidence energy (30 eV - 60 eV) and photon energy (15 eV) while at high energy only emission and absorption are responded for DCS. The DCS between absorption and emission of a photon with angle variation, dipole distance, and atomic polarizabilities was found 1.098 a.u.<sup>2</sup> and at high incidence, energies were found 0.1 a.u.<sup>2</sup>.
文摘研究了单个线性关系是可闭线性关系的充分必要条件;并对L0=(A B C D),其中A,B,C,D是相应Hilbert空间上的线性关系,利用C相对A的有界性与B相对D的有界性及A,D的可闭性,推出了L_(0)也是可闭线性关系;同时,对于有界线性算子S=(S_(1) S_(2) S_(3) S_(4)),得到当满足一定条件时L_(0)-μS的Frobenius-Schur分解公式,并得到了当L_(0)可闭时L_(0)的表达式,最后研究了L_(0)的S-本质谱。
基金supported by National Magnetic Confinement Fusion Energy Development Research Project(Nos.2022YFE03070003 and 2019YFE03070000)Natural Science Foundation of Hunan Province(No.2020JJ4515)+6 种基金Key Projects of Hunan Provincial Department of Education(No.20A432)the Government Sponsored Study Abroad Program of the Chinese Scholarship Council(CSC)(No.202108430056)Anhui Provincial Natural Science Foundation(No.2308085MA23)IAEA Coordinated Research Project F43026(No.26480)the National Key Research&Development Program of China(No.2018YFE0303103)National Natural Science Foundation of China(Nos.11875287 and 12275314)Anhui Provincial Key Research&Development Project(No.205258180096)。
文摘A program developed with COMSOL software integrates EAST four-strap antenna coupling with the double-stub Ferrite tuners(FT)impedance matching,obtaining physical quantities crucial for predicting the overall performance of the ion cyclotron resonance heating(ICRH)antenna and matching system.These quantities encompass S-matrix,port complex impedance,reflection coefficients,electric field and voltage distribution,and optimal matching settings.In this study,we explore the relationship between S-matrix,reflection coefficients,port complex impedance,and frequency.Then,we analyze the impact of Faraday screens placement position and transparency,the distance from the Faraday screen(FS)to the current straps(CS),the relative distance between ports,and the characteristic impedance of the transmission line on the coupling characteristic impedance of the EAST ICRH system.Finally,we simulate the electric field distribution and voltage distribution of the EAST ICRH system for plasma heating with double-stub FT impedance matching.Using optimized parameters,the coupling power of the ICRH system can be approximately doubled.The results present herein may offer guidance for the design of high-power,long-pulse operation ICRH antenna systems.
文摘双模离散傅里叶变换–扩展正交频分复用(discrete fourier transform–spreading-orthogonal frequency division multiplexing-discrete multi,DFT-S-OFDM-DM)系统虽然拥有优秀的峰均功率比(peak to average power ratio,PAPR)、信道适应能力以及低复杂度,但此系统在频谱效率(spectral efficiency,SE)表现上并不理想,系统中的离散傅里叶变换(discrete fourier transform,DFT)扩展和双模调制都有一定的改进空间。针对此系统,提出新的多维索引离散傅里叶变换-扩展正交频分复用(discrete fourier transform-spreading-orthogonal frequency division multiplexing-multi dimension index,DFT-S-OFDM-MDI)系统,新系统将DFT扩展改为DFT索引扩展,增加新的子载波索引位,增加双模调制搭配种类,提升双模索引位宽,进而提升系统SE。本文还为新系统配置6种双模星座图,并与预编码增益矩阵搭配,提升系统误码率(bit error ratio,BER)性能。仿真结果表明,系统具有优秀的SE和BER性能,优于多种传统方案。
