Compact megawatt average power burst pulse generator

A compact, lightweight, burst mode pulse generator has been designed and evaluated at a megawatt of average power. The modulator occupies a volume of 0.81 m³and weighs 225 kg. The recently developed MAPS-40 thyratron [1] and two high-energy density pulse-forming networks [2] (PFN) are used as the switch and energy store. A solid-state end-of-line clipper circuit is included and was found to be essential at high average power loadings. The modulator has been evaluated using a copper sulphate load at 40-kV peak voltage, 40-kA peak current, 10-µs pulsewidth, 40-kA/µs rise time,and 50 A of average current at a repetition rate of 125 Hz. Repeated burst on times of 5 s in a 35-s time period have been demonstrated.     

100-kV Hydrogen thyratron without gradient grids

A high-power hydrogen thyratron grid-anode structure has been developed using a 5949 thyratron cathode assembly. One such device was operated for 10 h at 2000 A, 32 kV, at 1400 pps with a pulse width of 0.3 µs. Another was operated for periods up to 220 h at 1000 A, 100 kV, at a duty cycle of 0.00004. The duty cycle is presently limited by our test modulator circuit. Trigger requirements are 2 kV at 50 Ω with a 2.5-µs duration. The jitter was nil when measured with a Tektronix 517 oscilloscope using a sweep speed of 50 ns/cm. The anode delay time is in the range of 1/4 to 1/2/ µs. The grid-anode geometry is designed for a minimum anode-grid capacity, thus providing a tube with a higher repetition rate capability. The field emission limit up to 100 kV is not evident in the normal sense in this geometry.     

Operation of a 300-kV, 100-Hz, 30-kW average power pulser

Applications for efficient and reliable pulse power systems with long lifetimes (>10⁸shots) are foreseen for electron-beam generators, ion-beam accelerators, and lasers leading eventually to inertially confined fusion reactors. These systems will have to be capable of continuous operation for sustained periods without requiring major maintenance or repair. High operating efficiency will be required not only to minimize power consumption but also to avoid heat buildup and consequent damage to components. The system described in this paper represents an initial effort to develop an efficient energy-handling high-voltage pulser to study the problems of long-life components.     

The plasma-heated thyratron

An instant-starting hydrogen thyratron is described which incorporates a cathode requiring no warmup time, no standby power, and no separate heater power supply. Starting cold, time jitter is less than 1 ns; anode delay time is less than200 ns; and the 0-30-s anode delay time drift is less than 100 ns. The cathode is a self-heating design made of impregnated tungsten. Even when cold, it provides sufficient emission capability to trigger readily and to prevent arcing. During operation, it attains full operating temperature via plasma-heating effects and its own resistive dissipation; after shutdown, it remains active, in readiness for the next cold start, a cycle which can be repeated as often as desired. Thyratrons made with the new cathode display operating behavior and life comparable to conventional hydrogen thyratrons of equivalent size.     

Dynamic avalanche in 3.3-kV Si power diodes

Measurements of the safe reverse recovery limit were performed for 3.3-kV Si power diodes using a novel optical experimental technique. In this experiment, influence of the junction termination is effectively eliminated by optical generation of a laterally-localized carrier plasma. The turn-off failures observed in measurements at two temperatures showed no temperature dependence and could not be reproduced in ordinary one-dimensional (1-D) or two-dimensional (2-D) device simulations. To simulate the stability of the current density toward current filamentation, two 1-D diodes with an area ratio 1:19 and a 10% difference in initial carrier plasma level, were simulated in parallel. This resulted in a strongly inhomogeneous current distribution, and a rapid reverse voltage fall resembling the measured turn-off failures. Inhomogeneous current distribution in these simulations appears as the current decay ceases due to impact ionization, in qualitative agreement with a current instability condition proposed by Wachutka [1991]     

能够产生连续电弧的1kV电源

设计一种能够产生连续电弧的高压开关电源可能是具有挑战性的.这种小巧高效的开关电源在输出功率为20W时可输出1kV电压,并能耐受连续电弧(即短路)(图1).它使用标准的市售元件.使用R1将开关稳压控制器LTC1871设定在120kHz的额定工作频率.该电路像间断式回扫电路一样工作,在C1上产生333V电压.二极管/电容器电荷泵倍增器把该电压升高到三倍,在输出端产生1000V电压.图2示出了该电路产生的开关波形.当初级开关Q1导通时,输出整流器被反向偏置,能量存储于变压器T1中.当Q1截止时,能量传输到次级线圈,C2和C3通过整流器提高输出电压.初级电压升高,并通过变压器和整流器D1箝位为C1上的电压.变压器耦合良好,所以漏电感几乎不会造成电压尖脉冲.跨接在初级线圈上的小型RC阻尼器可衰减阻尼振荡,并降低EMI(电磁干扰).     

High average power harmonic generation

High average power frequency conversion using solid-state nonlinear materials is discussed. Recent laboratory experience and new developments in design concepts show that current technology, a few tens of watts, may be extended by several orders of magnitude. For example, using KD*P, efficient doubling (> 70 percent) of Nd:YAG at average powers approaching 100 KW is possible; for doubling to the blue or UV regions the average power may approach 1 MW. Configurations using segmented apertures permit essentially unlimited scaling of average power. High average power is achieved by configuring the nonlinear material as a set of thin plates with a large ratio of surface area to volume, and cooling the exposed surfaces with a flowing gas. The design and material fabrication of such a harmonic generator is well within current technology.     

Development of a 2.6-kV light-triggered thyristor for electric power systems

The status of a present Electric Power Research Institute, Inc. (EPRI) funded research program on a directly light-triggered thyristor for high-voltage direct current (HVDC) application is reviewed. An existing 53-mm, 2600-V, 1000-A electrically fired device was suitably modified to be turned on with an incident photopulse of 30 nJ, the basic problem being the retension of a 2000-V/µsdV/dtcapability. Design tradeoffs betweendV/dtand gate sensitivity are discussed as well asdi/dtproblems encountered in turning on a 2-in device with such a small gate signal. Special experiments and design and analysis computer programs have helped in assessing temperature excursion during turn-on and led to improved design with adi/dtcapability approaching that of the original electrically gated device.     

Effect of hydrogen on the average output power of the UV Cu/sup +/ Ne-CuBr laser

The effect of different additives-air, synthetic air, N/sub 2/, O/sub 2/, CO/sub 2/, He, Ar, Xe, and H/sub 2/, to the neon buffer gas on the average output power of a UV Cu/sup +/ Ne-CuBr is investigated. It is found that the addition of small amounts of hydrogen, 0.02-0.04 torr, leads to an increase by more than twice of the average output power for simultaneous laser oscillation at the five Cu/sup +/ lines-248.6, 252.9, 259.7, 260.0, and 270.3 nm.     

The TDMA burst-mode link analyser with least-squares algorithm

The burst-mode link analyser with the decompositional least-squares algorithm (BMLA/LS) is an attractive and novel computational approach for impulse response measurement and equalization of a QPSK/TDMA satellite communication channel. Analysis and simulation confirms it to be superior to the current BMLA/radar approach. This paper presents a brief and systematic introduction to the methodology of the subject, and to software simulation, system design and hardware implementation.     

dBm average optical output power operation of small-chirp 40-gbps electroabsorption Modulator with tensile-strained asymmetric quantum-well absorption Layer

A small-chirp 40-Gbps electroabsorption modulator (EAM) with high optical output power capability has been developed for the first time. An optimized tensile-strained asymmetric quantum-well structure is employed as the absorption layer of the EAM so that small chirp and reduction of the lifetime of the photogenerated holes for high optical output power tolerance is obtained. Deteriorations of frequency response and chirp due to carrier pileup under high optical output power conditions were prevented by enhancing carrier sweepout, which was experimentally confirmed as a hole lifetime as short as 35 ps under high optical output power conditions. As a result, good frequency response (bandwidth > 30 GHz) and small chirp (/spl alpha/<1) were obtained under the condition of the zero bias voltage and +4.5 dBm continuous-wave (CW) optical output power (P/sub out,CW/). Clear eye opening and high dynamic extinction ratio under 40-Gbps non-return-to-zero modulation persisted to a high average output power (P/sub out,ave/) condition of P/sub out,ave/=+1.0 dBm.     

The 1.6-kV AlGaN/GaN HFETs

The breakdown voltages in unpassivated nonfield-plated AlGaN/GaN HFETs on sapphire substrates were studied. These studies reveal that the breakdown is limited by the surface flashover rather than by the AlGaN/GaN channel. After elimination of the surface flashover in air, the breakdown voltage scaled linearly with the gate–drain spacing reaching 1.6 kV at 20$muhboxm$. The corresponding static ON-resistance was as low as 3.4$hboxmOmega cdot hboxcm^2$. This translates to a power device figure-of-merit$V_ BR^2/R_ ON = hbox7.5times hbox10^8 hboxV^2 cdot Omega^-1 hboxcm^-2$, which, to date, is among the best reported values for an AlGaN/GaN HFET.     

High average power dissipation in helix tubes

By precisely shrinking the glass envelope around the helix to a controlled depth, thus providing an exceptionally low thermal impedance to the outside of the envelope, and passing a suitable coolant over the envelope, it has been found that the power dissipation capability of helix circuits can be extended by more than one order of magnitude. A qualitative analysis indicates that the heat transfer characteristics should be as good as the experimental results indicate.     

A reliable high average power dye laser

A pulsed dye laser using commercial xenon flashlamps in a novel pump geometry and using thyristors for switching having an average laser output power capability of 100 W is described.     

A 2-kW average power X-band receiver protector

A 2-kW average power receiver protector with a 5000-h operating life has been developed. The design is of the gas plasma diode hybrid type which heretofore could provide only one-tenth the power handling for equivalent operating life. Predicted life is based on experimentally obtained molecular sorption coefficients performed at 2-kW average power inXband. The device has been developed for use as a receiver protector in a high-resolution radar to be used at Lincoln Laboratory. This radar will transmit 200-kW average power atXband and consequently requires a high average power receiver protector.     

高平均功率电能激光器研究进展

高平均功率电能激光器在工业加工和定向能量传输、国防军事、激光钻油井等领域具有重要的应用前景.而且有效率高、结构紧凑灵活、热管理方便、后勤保障容易等优点.广泛关注了近几年来国外高平均功率电能激光器的研究进展,包括固体激光器、光纤激光器、液体激光器、自由电子激光器、碱金属蒸汽激光器、二氧化碳激光器及基于固体和光纤、半导体激光器的相干合成、非相干合成、光谱合成.在介绍了各种激光器工作原理和关键技术的基础上,详细分析了高平均功率电能激光器面临的技术挑战及未来的发展趋势.     

高平均功率太赫兹自由电子激光装置设计

为满足材料和生物医学等研究需要,中国工程物理研究院(中物院)提出了高平均功率太赫兹自由电子激光(THz FEL)用户装置研制项目。该装置采用准连续波运行的工作模式,太赫兹平均功率约为10 W。通过调节电子束能量和摇摆器的磁场强度,装置输出波长可在100μm(3 THz)~300μm(1 THz)进行调节,以满足不同用户的研究需要。装置主要包括电子源、主加速器、混合型摇摆器、激光谐振腔、太赫兹传输与探测系统等。装置将使用直流高压光阴极注入器作为电子源,主加速器为超导加速器,超导加速器后的电子束能量约8 MeV。该装置将建立成为一个用户装置。     

A 280-W average power Cu-Ne-HBr laser amplifier

A large-volume (19.5 L) laser tube has been built for the study of extrapolating power from the Cu-Ne-HBr laser medium. A high-power (50 kW) all-solid-state power supply has been also developed for this purpose. Results show a record optical power of 216 W extracted from this type of laser when used as an oscillator and 280 W as an amplifier