Research progresses on Cherenkov and transit-time high-power microwave sources at NUDT

Research progresses on Cherenkov and transit-time high-power microwave(HPM)sources in National University of Defense Technology(NUDT)of China are presented.The research issues are focused on the following aspects.The pulse-shortening phenomenon in O-type Cerenkov HPM devices is suppressed.The compact coaxial relativistic backward-wave oscillators(RBWOs)at low bands are developed.The power efficiency in M-Type HPM tubes without guiding magnetic field increased.The power capacities and power efficiencies in the triaxial klystron amplifier(TKA)and relativistic transit-time oscillator(TTO)at higher frequencies increased.In experiments,some exciting results were obtained.The X-band source generated 2 GW microwave power with a pulse duration of 110 ns in 30 Hz repetition mode.Both L-and P-band compact RBWOs generated over 2 GW microwave power with a power efficiency of over 30%.There is approximately a 75% decline of the volume compared with that of conventional RBWO under the same power capacity conditions.A 1.755 GHz MILO produced 3.1 GW microwave power with power efficiency of 10.4%.A 9.37 GHz TKA produced the 240 MW microwave power with the gain of 34 dB.A 14.3 GHz TTO produced 1 GW microwave power with power efficiency of 20%.

Determination of CeO_2 , Dy_2O_3, CuO and PbO in Yttrium Oxide Reference Material by Isotope Dilution Spark Source Mass Spectrometry

This paper describes the quantitative determination of rare-earth elements cerium, dysprosium and non-rare-earth element copper, lead and the homogeneity examination of these four elements in yttrium oxide reference material by isotope dilution spark source mass spectrometry (ID-SSMS). The sensitivity of the meth- od is l0^(-5)～10^(-7%). The precision is better than 6%. The accuracy is better than 5%. The interferences of the spectra and the optimum amount of the spike added to the sample are discussed. The choice of the conducting material for the sample electrodes is studied.

Simulation of Spark Source Wavelet Under Multibubble Motion

Marine spark sources are widely used in high-resolution marine seismic surveys.The characteristic of a wavelet is a critical part in seismic exploration;thus,the formation and numerical simulation of spark source wavelets should be explored.In studies on spark source excitation,the acoustic field generated by the interaction between bubbles constitutes the near-field wavelet of a source.Therefore,this interaction should be revealed by studying complex multibubble motion laws.In this study,actual discharge conditions were combined to derive the multibubble equation of motion.Energy conservation,ideal gas equation,and environmental factors in the discharge of spark source wavelets were studied,and the simulation method of an ocean spark source wavelet was established.The accuracy of the simulation calculation method was verified through a comparison of indoor-measured signals using three electrodes and the spark source wavelet obtained in the field.Results revealed that the accuracy of the model is related to the number of electrodes.The fewer the number of electrodes used,the lower will be the model's accuracy.This finding is attributed to the statistical hypothesis factor introduced to eliminate the coupling term of the interaction of the multibubble motion equation.This study presents a method for analyzing the wavelet characteristics of an indoor-simulated spark source wavelet.

Balmer H_α,H_β and H_γ Spectral Lines Intensities in High-Power RF Hydrogen Plasmas

Hα（Balmer-alpha）, Hβ （Balmer-beta） and Hγ （Balmer-gamma） spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectral lines are detected by increasing the input power （0-6 kW） of ICPs （inductively coupled plasmas）. With the increase of net input power, the intensity of Hα im- proves rapidly （0-2 kW）, and then reaches its dynamic equilibrium; the intensities of Hβ can be divided into three processes： obvious increase （0-2 kW）, rapid increase （2-4 kW）, almost constant （4-6 kW）; while the intensities of Hγ increase very slowly. The energy levels of the excited hydro- gen atoms and the splitting energy levels produced by an obvious Stark effect play an important role in the results.

火花源原子发射光谱法测定变形铝合金中痕量钠

变形铝合金是重要的高强度轻量化金属材料,具有良好的塑性加工与焊接性能,并广泛应用于航空、航天、交通和轻工等领域。针对现行电感耦合等离子体发射光谱法和原子吸收光谱法及火花源原子发射光谱法分析标准无法完全满足铝及铝合金中痕量钠杂质快速精准常规检验需求的现状,为发挥测试技术对变形铝合金材料工艺与应用研究的引导性作用,开展了火花源原子发射光谱法测定变形铝合金中痕量钠的分析方法应用。确定的分析条件:分析谱线为589.00 nm,氩气吹扫时间为3 s,预燃烧时间为11 s,火花数量为4400,曝光次数为1次,时间为4 s,火花数量为1600,火花频率均为400 Hz。对于钠杂质含量为2~30μg/g的变形铝合金标准样品和实际样品,其测定结果(n=6~9)的标准偏差不大于1.5μg/g,相对标准偏差小于10%,标准样品测定值与认定值相符,偏倚不大于2μg/g。方法可满足变形铝合金的快速精准常规检验的实际需求。

海洋电火花震源地震数据子波处理技术及应用

与海洋地震勘探中传统的气枪震源相比,海洋电火花震源由于其声学特性,在激发过程中会产生多个压力脉冲,同时由于海洋地震勘探中鬼波的干扰,使得电火花震源子波中具有更多的旁瓣,限制了地震子波的带宽,降低了地震数据的分辨率。电火花震源子波处理一般使用反褶积,但是反褶积技术单一,不能有效解决电火花震源子波复杂的问题。基于此,介绍了电火花震源子波复杂的原因,使用鬼波压制技术、tau-p域预测反褶积技术、零相位化技术对电火花震源子波进行处理,解决电火花数据子波形态不规则的问题,对鬼波进行了有效压制,恢复了电火花震源的子波频带,获得了宽频地震数据,提高了地震数据的分辨率,丰富了低频信息,提高了同相轴的识别能力。

High-power sub-picosecond all-fiber laser source at 1.56 μm

We demonstrate an all-fiber, high-power, and high stability ultrafast laser source operating at 1563 nm. A highly stable, self-starting carbon nanotube（CNT） mode-locked femtosecond fiber laser is used as the seed source. The amplifier stage uses a fiber chirped pulse amplification configuration. The main power amplifier is based on a cladding-pumped Er–Yb co-doped fiber with 10 μm active single-mode core diameter. The laser source provides 3.4 W average output power at 75 MHz repetition rate. The pulses are compressed to 765 fs by a low-loss transmission grating pair. The robust, compact, and high-power 1560 nm fiber laser source can be used for eye surgery and solar cell micromachining.

Design and characteristics investigation of a miniature low-temperature plasma spark discharge device

Atmospheric pressure low-temperature plasma is a promising tool in biomedicine applications including blood coagulation,bacterial inactivation,sterilization,and cancer treatment,due to its high chemical activity and limited thermal damage.It is of great importance to develop portable plasma sources that are safe to human touch and suitable for outdoor and household operation.In this work,a portable and rechargeable low-temperature plasma spark discharge device(130 mm×80 mm×35 mm,300 g)was designed.The discharge frequency and plume length were optimized by the selection of resistance,capacitance,electrode gap,and ground electrode aperture.Results show that the spark plasma plume is generated with a length of 12 mm and a frequency of 10 Hz at a capacitance of 0.33μF.resistance of 1 MΩ,electrode gap of 2 mm,and ground electrode aperture of 1.5 mm.Biological tests indicate that the plasma produced by this device contains abundant reactive species,which can be applied in plasma biomedicine,including daily sterilization and wound healing.

Spark发射光谱应用综述

较全面地介绍了目前常见的Ｓｐａｒｋ光电发射光谱仪（ＯＥＳ）所具有的性能，并从使用角度分析了不同型号仪器具有的不同分析对象，综述目前使用分析中的研究成果。

High-power all-fiber 1.0/1.5μm dual-band pulsed MOPA source

The simultaneous dual-band pulsed amplification is demonstrated from an Er/Yb co-doped fiber（EYDF）, and consequently a high-power all-fiber single-mode 1.0/1.5 μm dual-band pulsed master oscillator power amplifier（MOPA） laser source is realized for the first time, to the best of our knowledge, based on one singlegain fiber. The simultaneous outputs at 1061 and 1548 nm of the laser source have the maximum powers of 10.7 and 25.8 W with the pulse widths of 9.5 ps and 2 ns and the pulse repetition rates of 178 and 25 MHz, respectively. This EYDF MOPA laser source is seeded by two separate preamplifier chains operating at 1.0 and 1.5 μm wavebands. The dependence of the laser output powers on the length of the large-mode area EYDF, the ratio of the powers of the two signals launched into the booster amplifier, and the wavelength of the 1 μm seed signal are also investigated experimentally.

High-power sub-picosecond all-fiber laser source at 1.56 μm-corrigendum

The authors would like to apologize for some mistakes in the article and wish to make the corrections described below：1） Designate Youjian Song （宋有建） as the corresponding author of this article. His Email address is yjsong^tju.edu.cn.

基于图像邻帧像素灰度和的矿井电火花识别及报警方法研究

尽早发现矿井电火花并报警,可避免或减少瓦斯和煤尘爆炸及矿井火灾事故发生。井下没有日光、月光及星光等自然光源,影响矿井电火花识别的主要是矿井光源。通过调整摄像机的安装位置及角度,可以避免或减少矿井固定光源对电火花识别的影响,但不能解决矿井移动光源对电火花识别的影响。不同形式电路产生的电火花放电周期不同,但电火花放电时间均小于4 ms。闪光光源最小亮持续时间为240 ms。因此,可利用电火花发光时间短、矿井移动光源对摄像机照射时间较长的特点,排除矿井移动光源对摄像机照射的影响。摄像机在较高帧频下拍摄,电火花图像具有1帧暗-1帧亮-1帧暗的特征,即“暗-亮-暗”的帧特征。有电火花的“亮”帧,单帧图像像素灰度和较大;无电火花的“暗”帧,单帧图像像素灰度和较小。移动光源对摄像头的照射是变化的,经历了无光-有光-无光过程。在无电火花的情况下,摄像机同样在较高帧频下拍摄,无论是移动常亮光源还是移动闪光光源的图像均不会出现“暗-亮-暗”的帧特征。基于电火花图像独有的“暗-亮-暗”的帧特征,提出了基于图像邻帧像素灰度和的矿井电火花识别及报警方法:实时采集监控区域视频图像;根据设定的帧频,对视频图像进行分帧预处理,分别计算单帧图像像素灰度和;若当前帧图像像素灰度和与前一帧图像像素灰度和之差小于预先设定的阈值,则继续采集视频图像,否则计算当前帧图像像素灰度和与后一帧图像像素灰度和之差;若该差值小于预先设定的阈值,则继续采集视频图像,否则发出矿井电火花报警信号;矿井电火花报警后,若人工没有启动应急响应,则继续进行矿井电火花报警,否则退出当前报警状态,继续采集视频图像。通过该方法可有效消除移动常亮光源和闪光光源的干扰。

高采样频率的矿井电火花图像识别及抗干扰方法研究

隔爆外壳外的电缆和电气设备漏电、大功率无线电发射在金属支护和机电设备金属上感生电动势放电产生的矿井电火花,会引起瓦斯和煤尘爆炸及矿井火灾事故,因此有必要尽早感知矿井电火花。影响矿井电火花识别的主要是矿井光源,为减少矿井光源对矿井电火花图像识别的干扰,提出了一种高采样频率的矿井电火花图像识别及抗干扰方法:依据电火花的最长持续发光时间和闪光光源的最短持续发光时间,计算摄像机的采样频率,保证每次电火花出现时,电火花图像只出现在1帧图像上,且矿井光源存在时,干扰光源图像至少出现在连续2帧图像上;计算每帧图像的像素灰度和,若当前帧图像的像素灰度和与前后相邻帧图像的像素灰度和的差值均大于设定的阈值,则发出矿井电火花报警信号。试验结果表明:在无干扰光源条件下,该方法可准确识别矿井电火花图像,准确率达100%;在有日光灯、白炽灯等常亮光源干扰条件下,电火花与日光灯混合图像中电火花识别准确率达99.40%,电火花与白炽灯混合图像中电火花识别准确率达99.67%;在有闪光光源干扰条件下,电火花与闪光灯混合图像中电火花识别准确率达100%。

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.

基于海底沉积层厚度分析的人工鱼礁选址初步研究

人工鱼礁的建设可优化海域生态环境、养护生物资源,促进海洋持续健康发展。人工鱼礁选址是人工鱼礁建设的首要环节,开展人工鱼礁建设工作前必须对人工鱼礁进行科学选址。以大连市长海县大长山岛东北部海域人工鱼礁选址工作为例,使用“SIGPULSEM2电火花震源单道地震”对海域沉积层厚度进行勘测,根据海域各地层沉积厚度分布,结果表明,海域北侧沉积厚度大,不宜进行人工鱼礁建设,海域南侧沉积厚度小,适宜进行人工鱼礁建设。通过潜水调查方式对人工鱼礁海底投放情况进行跟踪调查,验证人工鱼礁建设可依据沉积层厚度进行最适选址。

煤田地震勘探的震源参数试验研究

煤田地震勘探探测环境复杂及受周围干扰因素的影响,导致震源使用受到限制,从而制约煤田勘探数据采集的准确性。选取典型的炸药震源、车载可控震源及电火花震源为例,分析震源激发条件、适用条件等,进行激发井深(6m, 8m, 10m, 12m, 14m, 16m)、震动叠加次数(1次,2次,3次,4次,5次,6次)等试验,优化震源参数,并通过应用实例对比分析试验效果。结果表明:炸药震源对于浅部地层信息反应较少,对深部地层敏感度更高;车载可控震源对于浅部地层和深部地层都有很好的勘探效果,综合效果好,但有时会受制于浅层低速层散射影响;电火花震源对于浅部地层信息反应较少,对较深地层敏感度更高,但是受其激发能量限制,对于深部地层勘探效果相对较差。

模拟退火法地表一致性剩余静校正在海洋电火花数据中的应用

近年来由于电火花震源技术的不断成熟,在海洋地震勘探中的应用越来越多,尤其是在海洋浅层地质勘探、井场调查等勘探项目中;相对于气枪震源,电火花震源采集时电缆沉放深度较浅,电缆深度受海浪影响起伏较大,同时纵向分辨率较高,地震数据对电缆沉放深度较为敏感,使得地震信号受电缆起伏、海浪等影响同相轴存在无规则抖动现象,这种抖动在叠加剖面上表现为同相轴连续性差,会影响地震资料解释的精度。本次研究分析了电火花地震数据静校正问题产生的原因,介绍了模拟退火法地表一致性剩余静校正的方法原理,并通过理论模型验证了该方法的可靠性,最后在电火花高分辨率浅层地质调查数据进行实际应用,较好地解决了数据中的静校正问题,静校正后电火花地震数据的层位连续性更强,并且真实的地质特征得到有效恢复。

电火花震源在煤矿采区三维地震勘探中的应用

电火花震源是一种典型的非炸药地震勘探震源,多用于海洋地震勘探中,具有安全、绿色、环保等优点。以往由于电火花震源体积笨重,施工效率低,在煤矿采区三维地震勘探中应用极少。随着技术进步,电火花震源实现了轻量化、智能化,能够适应各种地质工况的需求。山东省滕县煤田一采区三维地震勘探区地表村庄等障碍物较多,表层地震地质条件较为复杂,炸药震源激发离房屋近对建筑物破坏性大,偏移距过大又会造成地震剖面开天窗,目的层反射波不连续。经过调查对比分析,本次三维地震野外数据采用电火花震源激发,生产前进行了井深与电火花能量试验,确定了激发参数。结果所获单炮记录与地震剖面信噪比高、目的层反射波同相轴连续性好,能够满足煤矿采区三维地震精细勘探,取得了较好的应用效果。电火花震源可以作为一种补充震源,在煤矿采区复杂地表条件地震勘探中推广应用。

Data processing of the Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system and application to South China Sea data

The Kuiyang-ST2000 deep-towed high-resolution multichannel seismic system was designed by the First Institute of Oceanography,Ministry of Natural Resources(FIO,MNR).The system is mainly composed of a plasma spark source(source level:216 dB,main frequency:750 Hz,frequency bandwidth:150-1200 Hz)and a towed hydrophone streamer with 48 channels.Because the source and the towed hydrophone streamer are constantly moving according to the towing configuration,the accurate positioning of the towing hydrophone array and the moveout correction of deep-towed multichannel seismic data processing before imaging are challenging.Initially,according to the characteristics of the system and the towing streamer shape in deep water,travel-time positioning method was used to construct the hydrophone streamer shape,and the results were corrected by using the polynomial curve fitting method.Then,a new data-processing workflow for Kuiyang-ST2000 system data was introduced,mainly including float datum setting,residual static correction,phase-based moveout correction,which allows the imaging algorithms of conventional marine seismic data processing to extend to deep-towed seismic data.We successfully applied the Kuiyang-ST2000 system and methodology of data processing to a gas hydrate survey of the Qiongdongnan and Shenhu areas in the South China Sea,and the results show that the profile has very high vertical and lateral resolutions(0.5 m and 8 m,respectively),which can provide full and accurate details of gas hydrate-related and geohazard sedimentary and structural features in the South China Sea.

可控冲击波震源在地震勘探中的试验

近年来,国家对安全生产和环境保护的新要求越来越严格,尤其是炸药震源的使用限制条件越来越多。在安全生产形势严峻,火工品使用受限,现有的其他类型震源又无法满足地震勘探施工要求的区域,很大程度上限制了地震勘探方法的应用。可控冲击波技术是以脉冲功率技术为基础的新技术,该技术具有幅值和冲量可控,作业区域不受限制,可重复使用的特点。本文对可控冲击波技术及其发展历程进行简要介绍,并将现有可控冲击波设备改进后作为震源进行了激发地震波试验,对获取的地震资料进行定量分析,结果表明可控冲击波技术可以应用到地震勘探领域,同时提出了当前可控冲击波设备需要改进的技术问题。