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Four-wave mixing and six-wave mixing in a four-level confined atomic system

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Chinese Physics B 2009年第12期18卷 5354-5361页

作者：李昌彪张彦鹏聂志强郑淮斌史美震刘东宁宋建平卢克清 key laboratory for physical electronics and devices of the ministry of education & Shaanxi key laboratory of Information Photonic Technique Xi'an Jiaotong University

We have investigated coexisting four-wave mixing and six-wave mixing （SWM） in ultra-thin, micrometre and long vapour cells. There exists competition between Dicke-narrowing features and polarization interference in the micrometre cell. The oscillation behaviour of SWM signal intensities and linewidths results from destructive interference. With a larger destructive interference, the SWM signal in ultra-thin cells shows a narrow spectrum, in contrast to the long cell case. Due to the Dicke-narrowing features, a narrow spectrum can be obtained, and such spectra can be used for high precision measurements and metrological standards.

关键词： Dicke-narrowing features polarization interference multi-wave mixing

Enhancement and Suppression of Four-Wave Mixing in a Four-Level Atomic System

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Chinese Physics Letters 2010年第7期27卷 140-143页

作者：陈汝霖袁晨智王志国聂志强李院院张彦鹏 key laboratory for physical electronics and devices of the ministry of education Xi'an Jiaotong University Xi'an 710049

We report observations of the enhancement and suppression of four-wave mixing （FWM） in an electromagnetically induced transparency window in a Y-type ^85 Rb atomic system. The results show the evolution of the dressed effects （from pure enhancement to partial enhancement/suppression, and finally into pure suppression） in the degenerate-FWM processes. Moreover, we use the perturbation chain method to describe the FWM process. Finally, we observe the polarization dependence of the enhancement and suppression of the FWM signal.

关键词： OBSERVATION (Scientific method) MODULATION theory OPTICAL properties ELECTROMAGNETIC devices POLARIZATION (Nuclear physics) PERTURBATION (Mathematics)

Charging dynamics of a polymer due to electron irradiation:A simultaneous scattering-transport model and preliminary results

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Chinese Physics B 2012年第12期21卷 487-493页

作者：曹猛王芳刘婧张海波 key laboratory for physical electronics and devices of the ministry of education Department of Electronic Science and TechnologyXi'an Jiaotong University

We present a novel numerical model and simulate preliminarily the charging process of a polymer subjected to electron irradiation of several 10 keV. The model includes the simultaneous processes of electron scattering and ambipolar transport and the influence of a self-consistent electric field on the scattering distribution of electrons. The dynamic spatial distribution of charges is obtained and validated by existing experimental data. Our simulations show that excess negative charges are concentrated near the edge of the electron range. However, the formed region of high charge density may extend to the surface and bottom of a kapton sample, due to the effects of the electric field on electron scattering and charge transport, respectively. Charge trapping is then demonstrated to significantly influence the charge motion. The charge distribution can be extended to the bottom as the trap density decreases. Charge accumulation is therefore balanced by the appearance and increase of leakage current. Accordingly, our model and numerical simulation provide a comprehensive insight into the charging dynamics of a polymer irradiated by electrons in the complex space environment.

关键词： electron irradiation charging dynamics electron scattering charge transport polymer

Theoretical and numerical studies on a planar gyrotron with transverse energy extraction

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Chinese Physics B 2014年第10期23卷 581-586页

作者：陈再高王建国王玥 key laboratory for physical electronics and devices of the ministry of education Xi’an Jiaotong University Northwest Institute of Nuclear Technology

In this paper, we study the planar gyrotron theoretically and numerically. Applying the large-signal theory to the planar gyrotron, the wave equation of electric field and the equation of motion of an electron are simultaneously solved to obtain some characteristic parameters, such as the phase-space plot of electrons, working frequency, startup time, electronic efficiency, and output power of the device. To verify the formulations used in this paper, three-dimensional particle simula- tions are performed on the same device, and the numerical results accord well with those obtained by using the large-signal theory. Theoretical and numerical results show that the electronic efficiency can reach 21% for the prototype of the planar gyrotron working at the frequency of 0.81 THz.

关键词： planar gyrotron terahertz large-signal theory particle simulation

Effects of Linear Falling Ramp Reset Pulse on Addressing Operation in AC PDP

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Plasma Science and Technology 2006年第4期8卷 464-467页

作者：刘祖军梁志虎刘纯亮孟令国 key laboratory of physical electronics and devices of the ministry of education Xi'an Jiaotong UniversityXi'an 710049China

The effects of linear falling ramp reset pulse related to addressing operation in an alternating current plasma display panel （AC PDP） were studied. The wall charge waveforms were measured by the electrode balance method in a 12-inch coplanar AC PDP. The wall charge waveforms show the relationship between the slope ratio of the falling ramp reset pulse and the wall charges at the end of the falling ramp reset pulse which influences the addressing stability. Then the effects of the slope ratio of the linear falling ramp reset pulse on the addressing voltage and addressing time were investigated. The experimental results show that the minimum addressing voltage increases with the increase of the slope ratio of the falling ramp reset pulse, and so does the minimum addressing time. Based on the experimental results, the optimization of the addressing time and the slope ratio of the falling ramp pulse is discussed.

关键词： alternating current plasma display panel(AC PDP) ramp reset waveform,addressing voltage addressing time

Polarization enhancement and suppression of four-wave mixing in multi-Zeeman levels

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Chinese Optics Letters 2011年第7期9卷 79-82页

作者：王志国付雨欣宋悦代国宪问峰赵金燕张彦鹏 key laboratory for physical electronics and devices Ministry of Education Shanxi Key Laboratory of Information Photonic Technique Xi'an Jiaotong University

Polarization dependence of the enhancement and suppression of four-wave mixing （FWM） in a multi- Zeeman level atomic system is investigated both theoretically and experimentally. A dressing field applied to the adjacent transition can cause energy level splitting. Therefore, it can control the enhancement and suppression of the FWM processes in the system due to the effect of electromagnetically induced transparency. The results show that the pumping beams with different polarizations select the transitions between different Zeeman levels that, in turn, affect the enhancement and suppression efficiencies of FWM.

关键词： Polarization

Enhanced or suppressed six-wave mixing in a five-level atomic system

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Chinese Physics B 2011年第7期20卷 205-209页

作者：宋悦代国宪付雨欣赵金燕王志国张彦鹏 key laboratory for physical electronics and devices of the ministry of education and Shaanxi key laboratory of Information Photonic Technique Xi'an Jiaotong University

We show the enhancement and suppression of a six-wave mixing （SWM） signal in the electromagnetically induced transparency in a five-level SSRb atomic system. The results show the Autler-Townes splitting and the enhancement or suppression of SWM, which are caused respectively by a self-dressing effect and by an external dressing effect in the presence of mutual dressing between two SWM signals. In addition, we observe the polarization dependence of the enhancement and suppression of the SWM signals.

关键词： six-wave mixing electromagnetically induced transparency enhancement suppression

A New Method for Measuring the Wall Charge Waveforms of AC PDP

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Plasma Science and Technology 2004年第6期6卷 2567-2570页

作者：梁志虎刘祖军刘纯亮 key laboratory for physical electronics and devices of the ministry of education Xi'an Jiaotong University Xi'an 710049 China

A new method is developed to measure the wall charge waveforms in coplanar alternating current plasma display panel (AC PDP). In the method, two groups of display electrodes are selected from a coplanar AC PDP and two capacitors are respectively connected with these two groups of display electrodes in series, and a measuring circuit and a reference circuit are thus constructed. With the help of special processing, discharge takes place in the cells included in the measuring circuit under a normal drive voltage but no discharge takes place in the cells included in the reference circuit under a normal drive voltage. The wall charge waveforms are obtained from the voltage difference between the two capacitors. Using the method, the wall charge waveforms are measured during resetting period, addressing period and sustaining period for the 304.8mm (12-inch) test PDP panel. The result shows that the wall voltage is about 96V during the sustaining period.

关键词： plasma display panel wall charge measuring method

Relation between space-charge-limiting current and electric field enhancement factor at curved surface cathode

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Chinese Physics B 2010年第7期19卷 394-398页

作者：刘国治杨占峰 key laboratory for physical electronics and devices of the ministry of education Xi'an Jiaotong University Northwest Institute of Nuclear Technology

A two-dimensional solution of space-charge-limiting current for a high current vacuum diode with a spherical cathode is presented. The relation between space-charge-limiting current and electric field enhancement factor at the cathode surface for the diode with a curved surface cathode is also discussed. It is shown that compared with the current given by the conventional Child-Langmuir law, which describes the one-dimensional space-charege-limiting current, the two-dimensional space-charge-limiting current in such a diode is enhanced due to the electric-field enhancement along the cathode surface. Among practical parameter ranges, enhancement factor ηb approximately satisfies ηb Aβn, where β is the electric field enhancement factor at the cathode surface, and n is a constant between 1 and 2, which is confirmed to be universal for the diodes with curved surface cathodes.

关键词： diode space-charge-limiting current intense electron beam