Diagnostics of Parameters by Optical Emission Spectroscopy and Langmuir Probe in Mixtures (SiH_4/C_2H_4/Ar) Radio-Frequency Discharge

Optical emission spectroscopy and Langmuir Probe diagnostics were incorporated into the experiment, in which dust particles were formed in-situ by using reactive mixture gases （SiHa/C2H4/Ar） in a radio-frequency （RF） discharge plasma. The excitation temperature was first calculated by combining several optical emission spectra of argon lines and using a Boltzmann distribution to fit the experimental data, then the excitation temperature as functions of both gas pressure and RF power in SiH4/C2Ha/Ar discharges for different discharge conditions were obtained. Correspondingly, based on the measurement of the electron temperature by a Langmuir probe, the excitation temperature was compared with the electron temperature, and some discussions were presented. Finally the emission intensities of spectral lines of Si 390.6 ran, Si2＋ 380.6 nm and C＋ 426.7 nm were measured and presented as functions of pressure, RF power and flow rate of SiH4/C2H4.

Measurement of the O_2 Dissociation Fraction in RF Low Pressure O_2/Ar Plasma Using Optical Emission Spectrometry

Measurement of the oxygen dissociation fraction in RF low pressure oxygen/argon plasma using optical emission spectrometry is presented. The oxygen dissociation fraction and its evolutions as functions of operational parameters were determined using argon as the actinometer. At a pressure of 30 Pa, the oxygen dissociation fraction decreased from 13.4% to 9.5% as the input power increased from 10 W to 70 W. At an input power of 50 W, the oxygen dissociation fraction decreased from 12.3% to 7.7% when the gas pressure increased from 10 Pa to 40 Pa. The influences of operational parameters on the generation of atomic oxygen were also discussed.

Effects of back gate bias on radio-frequency performance in partially depleted silicon-on-inslator nMOSFETs

The effects of back gate bias(BGEs) on radio-frequency(RF) performances in PD SOI n MOSFETs are presented in this paper. Floating body(FB) device, T-gate body-contact(TB) device, and tunnel diode body-contact(TDBC) device, of which the supply voltages are all 1.2 V, are compared under different back gate biases by different figures of merit, such as cut-off frequency( fT), maximum frequency of oscillation( fmax), etc. Because of the lack of a back gate conducting channel, the drain conductance(gd) of TDBC transistor shows a smaller degradation than those of the others, and the trans-conductance(gm) of TDBC is almost independent of back gate bias. The values of fT of TDBC are also kept nearly constant under different back gate biases. However, RF performances of FB and TB each show a significant degradation when the back gate bias is larger than ～ 20 V. The results indicate that TDBC structures could effectively improve the back gate bias in RF performance.

Preliminary results of optical emission spectroscopy by line ratio method in the RF negative ion source at ASIPP

Optical emission spectroscopy(OES)using the trace rare gases of Ar and Xe have been carried out in a radio frequency(RF)driven negative ion source at Institute of Plasma Physics,Chinese Academy of Science(ASIPP),in order to determine the electron temperature and density of the hydrogen plasma.The line-ratio methods based on population models are applied to describe the radiation process of the excited state particles and establish their relations with the plasma parameters.The spectral lines from the argon and xenon excited state atoms with the wavelength of 750.4 and 828.0 nm are used to calculate the electron temperature based on the corona model.The argon ions emission lines with the wavelength of 480 and 488 nm are selected to calculate the electron density based on the collisional radiative model.OES has given the preliminary results of the electron temperature and density by varying the discharge gas pressure and RF power.According to the experimental results,the typical plasma parameters isTe2≈2-4 eV and ne≈1 x 1017-8 x 1017 m^-3 in front of plasma grid.

Numerical study on discharge characteristics influenced by secondary electron emission in capacitive RF argon glow discharges by fluid modeling

A one-dimensional（1D） fluid model of capacitive RF argon glow discharges between two parallel-plate electrodes at low pressure is employed. The influence of the secondary electron emission on the plasma characteristics in the discharges is investigated numerically by the model. The results show that as the secondary electron emission coefficient increases,the cycle-averaged electric field has almost no change; the cycle-averaged electron temperature in the bulk plasma almost does not change, but it increases in the two sheath regions; the cycle-averaged ionization rate, electron density, electron current density, ion current density, and total current density all increase. Also, the cycle-averaged secondary electron fluxes on the surfaces of the electrodes increase as the secondary electron emission coefficient increases. The evolutions of the electron flux, the secondary electron flux and the ion flux on the powered electrode increase as the secondary electron emission coefficient increases. The cycle-averaged electron pressure heating, electron Ohmic heating, electron heating, and ion heating in the two sheath regions increase as the secondary electron emission coefficient increases. The cycle-averaged electron energy loss increases with increasing secondary electron emission coefficient.

Rydberg electromagnetically induced transparency and Autler–Townes splitting in a weak radio-frequency electric field

We utilize an electromagnetically induced transparency(EIT) of a three-level cascade system involving Rydberg state in a room-temperature cell, formed with a cesium 6 S_(1/2)–6 P_(3/2)–66 S_(1/2) scheme, to investigate the Autler–Townes(AT)splitting resulting from a 15.21-GHz radio-frequency(RF) field that couples the |66 S_(1/2) → |65 P_(1/2) Rydberg transition.The radio-frequency electric field induced AT splitting, γAT, is defined as the peak-to-peak distance of an EIT-AT spectrum.The dependence of AT splitting γAT on the probe and coupling Rabi frequency, ?_p and ?_c, is investigated. It is found that the EIT-AT splitting strongly depends on the EIT linewidth that is related to the probe and coupling Rabi frequency in a weak RF-field regime. Using a narrow linewidth EIT spectrum would decrease the uncertainty of the RF field measurements.This work provides new experimental evidence for the theoretical framework in [J. Appl. Phys. 121, 233106(2017)].

Preparation and Characterization of Transparent Conductive Zinc Doped Tin Oxide Thin Films Prepared by Radio-frequency Magnetron Sputtering

High transparent and conductive thin films of zinc doped tin oxide （ZTO） were deposited on quartz substrates by the radio-frequency （RF） magnetron sputtering using a 12 wt% ZnO doped with 88 wt% SnO2 ceramic target.The effect of substrate temperature on the structural,electrical and optical performances of ZTO films has been studied.X-ray diffraction （XRD） results show that ZTO films possess tetragonal rutile structure with the preferred orientation of （101）.The surface morphology and roughness of the films was investigated by the atomic force microscope （AFM）.The electrical characteristic （including carrier concentration,Hall mobility and resistivity） and optical transmittance were studied by the Hall tester and UV- VIS,respectively.The highest carrier concentration of -1.144×1020 cm-3 and the Hall mobility of 7.018 cm2（V ·sec）-1 for the film with an average transmittance of about 80.0% in the visible region and the lowest resistivity of 1.116×10-2 Ω·cm were obtained when the ZTO films deposited at 250 oC.

Aerodynamic actuation characteristics of radio-frequency discharge plasma and control of supersonic flow

In this paper, aerodynamic actuation characteristics of radio-frequency(RF) discharge plasma are studied and a method is proposed for shock wave control based on RF discharge. Under the static condition, a RF diffuse glow discharge can be observed; under the supersonic inflow, the plasma is blown downstream but remains continuous and stable.Time-resolved schlieren is used for flow field visualization. It is found that RF discharge not only leads to continuous energy deposition on the electrode surface but also induces a compression wave. Under the supersonic inflow condition, a weak oblique shock wave is induced by discharge. Experimental results of the shock wave control indicate that the applied actuation can disperse the bottom structure of the ramp-induced oblique shock wave, which is also observed in the extracted shock wave structure after image processing. More importantly, this control effect can be maintained steadily due to the continuous high-frequency(MHz) discharge. Finally, correlations for schlieren images and numerical simulations are employed to further explore the flow control mechanism. It is observed that the vortex in the boundary layer increases after the application of actuation, meaning that the boundary layer in the downstream of the actuation position is thickened. This is equivalent to covering a layer of low-density smooth wall around the compression corner and on the ramp surface, thereby weakening the compressibility at the compression corner. Our results demonstrate the ability of RF plasma aerodynamic actuation to control the supersonic airflow.

A comparison of emissive and cold floating probe techniques for electric potential measurements in rf inductive discharge

A cold floating probe method was compared with the emissive floating probe method in terms of a low-pressure radio-frequency inductive discharge.The dependences of difference between the plasma potential and the floating potential on the electron temperature 1-8 eV,plasma density 109-1012 cm 3 and magnetic field 100-650 G were obtained.It was demonstrated that the difference between the potentials that obtained by these two methods can differ significantly from the expected value of 5.2 kTe/e for argon.

Influence of Discharge Parameters on Tuned Substrate Self-Bias in an Radio-Frequency Inductively Coupled Plasma

The tuned substrate self-bias in an rf inductively coupled plasma source is controlled by means of varying the impedance of an external LC network inserted between the substrate and the ground. The influencing parameters such as the substrate axial position, different coupling coils and inserted resistance are experimentally studied. To get a better understanding of the experimental results, the axial distributions of the plasma density, electron temperature and plasma potential are measured with an rf compensated Langmuir probe; the coil rf peak-to-peak voltage is measured with a high voltage probe. As in the case of changing discharge power, it is found that continuity, instability and bi-stability of the tuned substrate bias can be obtained by means of changing the substrate axial position in the plasma source or the inserted resistance. Additionally, continuity can not transit directly into bi-stability, but evolves via instability. The inductance of the coupling coil has a substantial effect on the magnitude and the property of the tuned substrate bias.

脉冲调制中波发射射频强度增益补偿方法研究

脉冲调制中波发射射频采用标准强度增益分析实施补偿,忽略了相对公共相位误差的影响,导致增益补偿结果存在失真情况。因此,提出脉冲调制中波发射射频强度增益补偿方法。估计脉冲调制中波的峰值脉冲能量,并结合脉冲能量块相对公共相位误差解析其相噪,通过划分场区分析射频强度的辐射场串扰值,构建记忆多项式增益补偿该串扰值。实验结果表明:依据所提方法应用后得出的增益补偿结果,未出现失真情况,补偿效果较好。

Eye on the Sky: A UAP Research and Field Study off New York’s Long Island Coast

A ten-month field research study was meticulously conducted at Robert Moses State Park (RMSP) on the south shore of Long Island, NY. The objective was to determine if aerial phenomena of an unknown nature exist over a coastal location and to characterize their properties and behaviors. Primary and secondary field observation methods were utilized in this data-centric study. Forensic engineering principles and methodologies guided the study. The challenges set forward were object detection, observation, and characterization, where multispectral electro-optical devices and radar were employed due to limited visual acuity and intermittent presentation of the phenomena. The primary means of detection utilized a 3 cm X-band radar operating in two scan geometries, the X- and Y-axis. Multispectral electro-optical devices were utilized as a secondary means of detection and identification. Data was emphasized using HF and LF detectors and spectrum analyzers incorporating EM, ultrasonic, magnetic, and RF field transducers to record spectral data in these domains. Data collection concentrated on characterizing VIS, NIR, SWIR, LWIR, UVA, UVB, UVC, and the higher energy spectral range of ionizing radiation (alpha, beta, gamma, and X-ray) recorded by Geiger-Müller counters as well as special purpose semiconductor diode sensors.

Electric and plasma characteristics of RF discharge plasma actuation under varying pressures

The electric and plasma characteristics of RF discharge plasma actuation under varying pressure have been inves- tigated experimentally. As the pressure increases, the shapes of charge-voltage Lissajous curves vary, and the discharge energy increases. The emission spectra show significant difference as the pressure varies. When the pressure is 1000 Pa, the electron temperature is estimated to be 4.139 eV, the electron density and the vibrational temperature of plasma are /peak /lPeak which describes the electron temper- 4.71 x 10^11 cm-3 and 1.27 eV, respectively. The ratio of spectral lines ＂391.4/＇380.5 ature hardly changes when the pressure varies between 5000-30000 Pa, while it increases remarkably with the pressure below 5000 Pa, indicating a transition from filamentary discharge to glow discharge. The characteristics of emission spec- trum are obviously influenced by the loading power. With more loading power, both of the illumination and emission spectrum intensity increase at 10000 Pa. The pin-pin electrode RF discharge is arc-like at power higher than 33 W, which results in a macroscopic air temperature increase.

Radio-frequency system of the high energy photon source

Purpose High energy photon source is a 6 GeV diffraction-limited storage ring light source currently under construction in Beijing.A low-frequency fundamental radio-frequency(rf)system of 166.6 MHz was proposed to accommodate the accelerator physics design.Superconducting rf(srf)technologies were chosen for the storage ring rf accompanied by solid-state power amplifiers and digital low-level rf controls.The design of the rf system was completed,and the parameters are frozen.Elucidation of the rf design with key parameters is desired.Methods The requirements from the accelerator physics design will be presented followed by the detailed rf design.The logic behind the choice of key rf parameters is elaborated.The configuration of the entire rf system is presented.Results and conclusions The fundamental srf cavity of 166.6 MHz was designed to accelerate the ultrarelativistic electron beam.Heavy damping of higher-order modes in these cavities is required to avoid the coupled bunch instabilities.An active third harmonic srf of 499.8 MHz was adopted to realize the required rf gymnastics.Normal-conducting 5-cell cavities will be used for the booster rf.Solid-state amplifiers of 2.4 MW in total will be installed at HEPS to drive these cavities in the booster and the storage ring.A digital low-level rf system will be used to regulate rf field inside each cavity with high stabilities.The rf configuration during the commissioning and the operation scenarios are also presented.

电场辐射发射试验测试系统场强噪声计算方法

在开展电场辐射发射试验时,测试系统10 kHz~18 GHz极宽频带范围内场强噪声的准确预测是后续电磁兼容试验规避潜在风险、能够顺利开展的关键所在。场强噪声预测问题一直困扰着试验人员或电磁兼容实验室的设计人员。为此,根据电场辐射发射试验测试系统中各设备的级联关系,建立了测试系统的级联噪声模型,结合设备电磁参数给出了场强噪声的计算公式。计算结果与实测结果相比,两者趋势一致、吻合较好,计算公式在30~200 MHz和200 MHz~1 GHz的适用性最好。场强噪声计算方法可用于电磁兼容测试系统中场强噪声的预测和评估。

基于远程手术功能的辅助医用手术机器人无线共存评估研究

目的:探究辅助医用手术机器人无线共存评估方法,以保障医疗器械的安全性和有效性。方法:结合美国无线共存评估国家标准(ANSI)C63.27-2017的要求,阐述无线共存的基本要求、测试计划的制定,分析在单个电波暗室中进行无线共存测试的具体方法。结果:得到辅助医用手术机器人无线共存评估的具体方法。结论:基于远程手术功能的辅助医用手术机器人无线共存评估方法,可对保障手术机器人的安全性和有效性提供重要支撑。

5G移动通信网络智能节能应用方案

文章通过对鄂尔多斯市5G移动通信网络设备的能源消耗分析,根据网络选定区域内小区的历史业务数据,构建基站业务负荷预测模型,分别应用“符号关断”“RF智能关断”“载波关断”这三项节能措施,持续挖掘无线设备级节能功能的技术与方案,进一步优化节能参数,降低全网基站功耗,达到降本增效的目的。

钼尖场致发射阵列阴极的性能研究

利用微细加工技术和双向薄膜沉积技术对钼尖场发射阵列阴极的工艺进行了较为细致的研究 ,并在专用的真空系统中对所得阵列阴极的发射性能进行了测试 ,得到了一定的场致发射电流密度值。测试中采用数据采集系统监测栅极电压、阳极电压、阳极电流和栅极电流 ,测量了阴极阵列的发射稳定性和发射噪声。对发射的失效机理进行了实验研究和分析 ,认为发射失效的主要原因在于栅极和基底之间的漏电 ,尖锥和栅极孔间的暗电流 ,电极间的放电和放气 ,以及环境真空度和尖锥的不均匀性等。

北京自由电子激光装置的设计研究

北京自由电子激光装置(BFEL)是一台工作在中红外区的康普顿型FEL振荡器。由一台30MeV的射频电子直线加速器提供电子束。特点之一是用微波电子枪作为高亮度注入器。本文首先概述了BFEL的一般情形和物理参数.接着用解析公式和模拟的方法论证了电子束的设计目标和激光器的运转特征。最后阐述了BFEL各部分采取的技术路线的特点,内容包括微波枪、加速器和微波系统、调制器、输运系统、摇摆磁铁、光学腔、电子束诊断、准直、自发辐射和激光实验。

场致发射与二次电子倍增效应的程序开发

与瑞士保罗希尔研究所合作,在双方合作开发的通用加速器模拟程序库OPAL中添加了3维复杂几何处理模块及场致发射与二次电子发射模块,使得OPAL具备了进行3维复杂结构中场致发射与二次电子倍增效应模拟的能力,可用于优化复杂高频/微波器件的结构设计从而抑制暗电流发射或二次电子倍增效应。