Investigations of two-stage-pseudospark switches for high-currentapplications

To avoid the lowering of the holdoff voltage due to the electrode erosion in one stage high current pseudospark switches (PSS), a two stage PSS with no axial aperture in the intermediate electrode was tested. For investigations a pulse generator was used generating peak currents up to 120 kA at a maximum voltage of 30 kV with a period length of 5 μs of a weakly damped sine wave with 90% current reversal. In comparison with a one stage PSS the breakdown characteristic was shifted to higher pressure. With a free floating intermediate electrode, the device could not be triggered, however, with additional capacities of a few nF between the three electrodes the discharge was ignited. The discharge in the second gap is triggered by the pseudospark discharge in the cathode gap, discharging the auxiliary capacities. Simultaneously, observation of both gaps with fast shutter photography showed an independent movement of the discharges in the two gaps. In the cathode gap as current increases, the discharge moves away from the center to the plane electrode surface as has been observed in the one stage PSS. However, in the anode gap the discharge moves away from the center after a contraction to the center. The two discharges are transmitted to metal vapor arc type discharges as the erosion patterns prove. With this kind of a two stage PSS holdoff voltages exceeding 35 kV would be possible. The characteristic switch data, i.e., delay and jitter, are nearly equal to a one stage PSS     

脉冲锁模单脉冲选出同步电路

用国产雪崩管串驱动四电极触发管的高压开关从简易脉冲双锁模激光器中选出了稳定的亚毫微秒激光脉冲． 本文介绍了高压开关及同步电路的制作及实验情况。     

Low voltage firing characteristics of a triggered vacuum gap

The triggered vacuum gap is a normally nonconducting device in which a high-current metal-vapor arc can be established by a suitable pulse of current to a triggering electrode. While this gap is well suited to switching applications at high voltage, it has properties which make it useful at low voltage as well. The operation of the triggered vacuum gap has, therefore, been studied in the range 100 to 1000 volts. It was found that, although the gap could be triggered with currents as low as 0.02 amperes, consistent triggering with firing delays less than a microsecond required trigger pulses of 10 amperes or more. Little or no dependence of firing time on main gap voltage was observed. Below a few hundred volts, however, the probability of establishing a stable main discharge with a short duration trigger pulse falls off rapidly with decreasing gap voltage. The polarity of the main gap voltage and of the trigger pulse strongly influenced the firing characteristics of the gap in the range studied. These effects are discussed in detail.     

CO2激光诱导大气放电特性的研究

为了研究脉冲CO₂激光诱导空气放电的特性,建立了高压电容充放电实验平台,采用间距为8mm、半径为10mm的一对球形石墨电极,取得了放电电压和电流的实时数据,采用2阶振荡电路模型对放电电压和放电电流进行拟合得到了电极间激光诱导放电等离子体的阻抗,并对放电时间、放电延时及抖动做了统计。结果表明,激光诱导放电等离子体的阻抗很小,约1Ω~2Ω,拟合得到的放电等离子体阻抗随放电电压、放电电容、以及激光能量的增加而减小;放电延时随着实验条件的变化在2μs~10μs之间变化,放电延时以及延时抖动随着放电电压和激光能量的增加而降低,而受放电电容大小的影响不明显。由此高稳定性的激光脉冲和高压有助于激光诱导放电过程的稳定。     

The MAPS-40 burst-mode 40-kV megawatt average power hydrogen thyratron

A hydrogen thyratron capable of switching 40 kV and 40 kA in repetitive bursts at the 1-MW average power level is described. Major design problems were obtaining the necessary forward and inverse holdoff capability and controlling the thermal and mechanical effects of the several kilowatts of operating dissipation encountered at this power level. A conventional external anode, planar-electrode, ceramic-metal tube design was chosen to meet the design requirements, which include reliable, kickout-free operation following long periods of standby. Emission was provided by a large cathode specifically designed to handle ohmic heating due to the 1500 A of rms-equivalent pulse current, as well as the heat developed in the surrounding plasma. Massive auxiliary, control, and gradient grids were incorporated into a tightly baffled box-type grid structure of sufficient total aperture area to prevent quenching below 70-80 kA. Molybdenum wall shielding was employed to improve holdoff capability and prevent arc damage. Design and operating considerations are discussed and representative test results for the first 16 tubes are given, together with the results of special tests for high peak current, high average current, and high-voltage holdoff.     

Development of a 100-kV multimegawatt repetition rate gas switch

A 100-kV gas switch has been developed and tested which is capable of controlling 5-MW average power when operated up to 250- pps repetition rate. Recovery of the switch voltage holdoff capability after each discharge was accomplished by providing both a 1-ms grace period during which no voltage is reapplied, and by continuously purging the switch with 40-psig pressurized air at flow rates up to 60 SCFM. The switch was tested using a simulation technique in which the switch was subjected to the same repetitive peak voltage and current as it would in controlling several megawatts of average power. Limits of switch performance as a function of air flow rate and peak voltage have been established.     

精密长延迟纳秒高压脉冲源

介绍一种为大电流开关点火的精密长延迟纳秒高压脉冲源的研制。采取低压固体电路与大小氢闸管电路的合理配置，较好地解决了精密长延迟和高压脉冲输出时低延迟时间晃动的难点。该源具有延迟时间晃动小和可调的精密长时间延迟、上升时间小和幅度大的脉冲输出、抗强脉冲干扰等特性。     

Life extension of thyratrons in short-pulse circuits with use ofsaturable magnetic sharpeners

The design of magnetic pulse sharpening circuits for thyratron switching applications is presented. It is useful to add a saturating magnetic switch in series with the tube. Addition of the magnetic device reduces anode dissipation, hence reducing thyratron cooling requirements. The saturating magnetic switch allows the anode voltage to collapse while delaying the forward current, thus reducing the electron energy to a level below that which results in erosion. The complex interrelated issues of material selection, electrical parameters, core reset, and mechanical engineering are considered for the development of an integrated point design. Test results are presented, and life extension to >10¹⁰ shots is discussed     

Triggered vacuum gaps

Characteristics of a sealed vacuum gap are described and the difficulties encountered in applying this gap as an overvoltage protection device are discussed. It is shown how these difficulties can be ameliorated by the use of gas-free electrode materials and by triggering the gap when breakdown is required. Several methods of triggering are discussed and some practical triggering devices are described that inject minute quantities of ionized hydrogen into the gap. The hydrogen is eventually recovered by the use of a titanium hydride getter. It is shown that breakdown of the gap can be accomplished in less than one-tenth microsecond by first producing a glow discharge that is rapidly transformed into a metal-vapor arc. Properties of the metal-vapor arc are described which have an effect on the characteristics of the vacuum gap. A number of practical sealed-off triggered vacuum gaps are illustrated. These are used to carry microsecond capacitor discharge currents and 60-cycle power line currents for ½ cycle. The operating voltage range is from a few hundred volts to 100 kV. The advantages of vacuum gaps over gas-filled gaps are given and a number of overvoltage protection and switching applications are listed.     

A reverse-voltage protection circuit for MOSFET power switches

When MOSFET is used as a power switch, it is essential to prevent reverse current flow through the parasitic body diodes under reverse voltage condition. A new built-in reverse voltage protection circuit for MOSFETs has been developed. In this design, an area-efficient circuit is used to automatically select the proper well bias voltage to prevent reverse current under the reverse-voltage condition. This built-in reverse protection circuit has been successfully implemented in a high-side power switch application using a 0.6-μm CMOS process. The die area of the protection circuit is only 2.63% of that of a MOSFET. The latch-up immunity is greater than +12 V and -10 V in voltage triggering mode, and greater than ±500 mA in current triggering mode. The protection circuit is not in series with the MOSFET switch, so that the full output swing and high power efficiency are achieved     

基于功率MOS型场效应管的4 kV纳秒脉冲源

为了用固体开关器件替代国外氢闸流管,开展了大功率高速高压半导体固体开关及与其相配的高速高压组合电路研究。利用功率MOS型场效应管的开关原理,提出了对功率MOS型场效应管的栅极"过"驱动技术,提高了功率MOS型场效应管的开关速度,研制出基于功率MOS型场效应管的输出脉冲幅度大于4 kV,前沿小于10 ns,脉冲宽度大于100 ns的高压快脉冲驱动源。     

金属蒸气激光脉冲放电电路的模拟比较

通过对脉冲放电金属蒸气激光放电管等离子体电阻和闸流管的开关特性的实验测量和数学拟合,给出了两者阻抗随时间变化的指数关系式,进而模拟并测量了谐振倍压电路和Blumlein电路的放电脉冲波形以及闸流管开关时间对放电特性的影响,得到了和实测波形相一致的理论模拟结果。表明,这种模拟方法对激光器实现高效脉冲放电起到辅助设计的作用。     

±60 kV三电极场畸变气体开关静态特性研究

在高功率脉冲Marx发生器中,气体开关具有连接储能器件与负载作用。文中为一种高能量输出、高频Marx发生器,设计了一种三电极场畸变气体开关。开关电极采用同轴结构,具有体积小、放电电流大和工作电压范围宽等优点;通过实验对不同气压和电极间距下场畸变气体开关电极静态特性进行了测试,实验结果表明,场畸变气体开关自击穿电压随SF6气压的增长从线性增长到非线性增长;工作电压范围随场畸变气体开关两主电极之间距离的增大而增大,最终趋于平缓;击穿电流和电压的分散性都随着工作气压的增大而增大。     

Double-ended hydrogen thyratrons for crowbar protection of high-power TWT systems

The doubt-ended multigap ceramic thyratron is a versatile switch for crowbar applications. It will provide protection over a very wide range of HT voltages and will operate within a submicrosecond time delay. Since the tube operates in a normal nondestructive "thyratron mode" it will fire reliably for many millions of shots. Practical crowbar conditions can be complex, in particular with floating-deck modulators where stray capacitance and inductance can cause the HT voltage to ring and sometimes completely reverse. In the event of voltage reversal, the double-ended thyratron conducts smoothly in the reverse direction as the circuit requires. The paper describes a new range of compact double-ended thyratrons specifically designed for crowbar use up to 100 kV with an auxiliary power consumption of only 75 W. A dynamic test arrangement is described which demonstrates the tube's capability of discharging 0.75µF charged to 60 kV, the current rising to 5000 A at a rate of 50 kA/µs, with an anode delay time of 200 ns. The test equipment simulates either grounded cathode or floating-deck operation under conditions where a flash arc fault occurs. The efficiency of the protection is evaluated by monitoring the "let-through current" (i), charge (it), and energy (i_{2}t). Coincidence counters register faulty operations. A compact auxiliary supply module makes these tubes especially attractive to aerospace systems engineers.     

一体化油绝缘循环冷却系统在铜蒸汽激光器上的应用

研制了集合铜蒸汽激光器功率电容、电感、磁开关与闸流管的集成油绝缘循环冷却系统 ,以改进原铜蒸汽激光器系统中功率元件分离和冷却方式复杂所造成的系统长期运行的不稳定性。改进后的系统工作状态良好 ,解决了铜蒸汽激光器小型化与系统绝缘冷却之间的空间矛盾 ,克服了在阳极水冷过程中由于高压电解腐蚀造成管节处堵塞的缺点。     

An optically-coupled high-voltage p-n-p-n crosspoint array

A solid-state crosspoint array compatible with electromechanical switches has been developed in order to realize high-performance telephone exchange networks. The optically-coupled high breakover voltage crosspoint array discussed in this paper has achieved complete isolation of the speech path from the triggering circuit while it can be triggered directly by a transistor-transistor logic (TTL) level signal from the control circuit. The crosspoint array has a unique photo-coupling structure which allows four p-n-p-n elements to be triggered effectively by only one LED, maintaining up to 200 V/0.1 /spl mu/s dv/dt characteristics. It provides breakover voltage of up to 450 V, gate trigger LED current less than 20 mA, ON-state resistance within 4.5 /spl Omega/ and OFF-state capacitance less than 7 pF. The matrix arrangement is a 1/spl times/4 configuration; it is composed of a two wire bidirectional circuit and packaged in a 16-pin ceramic DIP. These device characteristics make possible the realization of solid-state crosspoint array practically compatible with the conventional electromechanical switch, particularly meeting requirements of miniaturization, low-power dissipation, and inexpensive construction. Accordingly, direct interface with conventional telephone sets is possible.     

The influence of arc chamber wall material on arc gap dielectricrecovery voltage

The dielectric breakdown strength of an arcing contact gap after current zero was compared when using alumina, polyamide 6/6 (PA 6/6), and polyoxymethylene (POM) arc chamber wall materials. Plasma characteristics were obtained for each material by applying a reverse recovery voltage across the open contacts at a predetermined delay time after current zero. Ablation from each type of chamber wall material produced different plasma compositions each with different recovery voltage, arc voltage, and pressure characteristics. Tests were performed for an arcing current of 12 kA_p, for one half-cycle using symmetric AgW contacts. A thermal breakdown model along with an exponential curve fit to the measured results were used to obtain the initial holdoff voltage and plasma time constant for each material. PA 6/6 and POM had similar time constants with PA 6/6 having slightly better performance. Two types of breakdown mechanisms were identified-thermal and dielectric     

不同激光二极管能量触发下GaAs 光导开关研究

GaAs 光导开关在较高的场强下可工作于雪崩模式,为此设计了异面体结构的GaAs 光导开关以提高开关场强。 设计的开关芯片厚度为2mm,电极间隙为3mm,利用半导体激光二极管对开关进行了触发实验。当开关充电电压超过 8kV 后,开关输出脉冲幅度显著增强,输出脉冲前沿快于光脉冲,开关开始了雪崩工作模式,且随着开关电场不断增加, 开关输出电压幅值也线性增加。在不同触发能量下,开关输出电压幅值和波形基本没有改变,但在较高的触发能量和高 的偏置电场下,开关抖动较小,实验中开关获得的最小抖动约500ps。     

类火花开关管

类火花放电是５０ 年代末期发现的一处低气压气体放电现象。利用这种放电现象制成的一种真空电子器件即类火花开关管，具有耐压高、功率大、电流上升速度快和重复频率高等特点。这种开关管可以替代闸流管、触发管、真空开关管和引燃管等器件，在高功率脉冲装置中应用，其效果良好。文中叙述了类火花放电的过程和特征、类火花开关管的特点、触发方式、种类及其结构特点，最后指出了类火花开关管的应用及其发展前景     

半导体激光二极管触发GaAs光导开关

半导体激光二极管触发下砷化镓（GaAs）光导开关工作于雪崩模式,为此设计了异面体结构的GaAs 光导开关以提高开关场强.设计的开关芯片厚度为2 mm,电极间隙为3 mm,利用半导体激光二极管对开关进行触发实验.当开关充电电压超过8 kV 后,开关输出脉冲幅度显著增强,输出脉冲前沿快于光脉冲,开关开始雪崩工作模式.随着开关电场不断增加,开关输出电压幅值也线性增加,但开关输出波形没有改变.对开关抖动进行测试,其测试结果显示开关偏压对抖动影响很大,随着开关偏压增加,开关抖动减小,当开关偏压升至15 kV 时,开关获得最小抖动约500 ps.