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1.
根据等效放电回路,火花电阻公式以及巴邢定律,推导出了高压纳秒脉冲参量与储能电容,放电等管内气压以及管内电极间距之间关系的解析式。公式与实验能较好地吻吻合。 相似文献
2.
对带有圆形埋藏裂纹金属构件在脉冲放电瞬间的应变能密度进行了理论分析。在求解过程中,以张开型裂纹为例,应用了热传导、非定常热应力及汉克尔变换等理论知识,得出了含埋藏圆片裂纹在脉冲放电瞬间的温度场理论公式、热应力场公式和应变能密度公式。由热应力场公式和应变能密度公式可知,放电瞬间电磁热在裂纹尖端形成热压应力场,热压应力对金属构件做负功,减小了拉应力对构件的破坏程度,放电后构件的应变能密度降低了。以Cr12MoV模具钢中埋藏圆裂纹止裂为例,具体计算了脉冲放电前后不同拉应力作用下的应变能密度变化情况,为空间裂纹电磁热止裂技术的实际应用提供了理论基础。 相似文献
3.
为研究水下等离子体声源放电系统的声效率问题,系统地分析了水下等离子体电晕放电和电弧放电两种放电方式的微观机理以及等离子体声源放电系统各部分之间的能量转换流程,建立了一套完整的系统声效率计算模型,同时设计了水下等离子体脉冲放电试验系统.通过比较和分析水下脉冲电晕放电和水下脉冲电弧放电的声效率发现,系统中电弧放电的声效率明显高于电晕放电.通过水下高压脉冲放电试验,详细分析了水下等离子体放电系统中关键部件对系统声效率的影响.分析结果表明:关键部件的设计和参数的优化配置对整个系统的声效率有重要影响;通过声效率的分析,能够准确评估水下等离子体声源的设计合理性. 相似文献
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为研究水中亚毫秒脉冲放电过程液相温度的变化,构建了适用于水中脉冲放电的纹影观测系统,提出了水中脉冲放电过程温度诊断系统的影响因素及标定方法,获得了水中脉冲放电过程温度场的径向分布。与有限元仿真对比分析表明,当径向距离小于0.9 mm时,纹影诊断温度相对于仿真结果的偏差小于8%,为水中脉冲放电机理研究提供了技术基础。 相似文献
6.
对气液串联放电反应器中悬浮活性炭对降解有机污染物的影响及联合处理过程中活性炭的作用进行了研究。结果表明:46kV脉冲流光放电与5g/L水洗活性炭联合处理具有协同效应,甲基橙的降解率提高22%;与5g/L吸附饱和的活性炭联合处理,比单独脉冲放电处理降解率提高12.25%,说明活性炭在联合处理中不仅有吸附能力,而且还具有催化作用。在上述两种条件下分别加入5ml/L H2O2,对·OH的产生具有协同效应,不但提高了O3和UV的利用率,而且还有利于活性炭的再生。 相似文献
7.
复合高功率脉冲磁控溅射放电等离子体特性 总被引:2,自引:0,他引:2
高功率脉冲磁控溅射具有高的金属离化率,在薄膜制备表现出巨大的优势,成为当前磁控溅射技术领域一个新的发展趋势。高功率脉冲磁控溅射的放电特性、等离子体特性等微观参数对薄膜质量控制具有决定性作用,分析宏观参数如何影响微观参数,有利于提高薄膜质量,稳定工艺。因此,本文研究了脉冲与直流电源并联模式的复合高功率脉冲磁控溅射过程中,脉冲电压(400~800 V)对Ti、Cr靶在Ar气氛中的放电特性、等离子体参数(等离子体电势、电子温度、电子密度)、基体电流的影响。结果表明:复合高功率脉冲磁控溅射Ti、Cr靶放电过程中,脉冲电压的增加有利于脉冲作用期间的靶电压、靶电流、基体电流增加;当Ti靶脉冲电压为600 V或Cr靶脉冲电压为700 V时,电子密度出现较大值。Cr靶与Ti靶放电相比,前者的靶电流、基体电流、等离子体电势、电子温度比后者更高,而电子密度却更低。 相似文献
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以冷阴极等离子体交叉场调制开关为研究对象,将系统内放电过程中形成的等离子体视为电子与正离子构成的双流体,引入扩散系数与迁移率来表征电子流与离子流的运动,用离子产率来表征与流体密切相关的离子密度随放电时间的进行而发生的变化,耦合泊松方程来描述等离子体与外电场的相互影响,同时,将气体间隙的脉冲放电合理的与直流放电等效,并确定外电路各量之间的函数关系,利用Comsol软件对调制开关的导通过程进行了数值模拟,所得结果与实测结果吻合,证明了模拟脉冲放电中管内阻抗随时间的变化关系是准确的,从而说明本文所采用的模拟方法对气体放电器件的研制具有积极的指导意义。 相似文献
10.
在小型消声水池中,同步测量水下等离子体脉冲声源的放电特性和声特性,实验分析研究了其在单电极和多电极下负载注入峰值功率和放电能量对声特性的影响。结果表明,在相同的电极数和间距下,直达波脉冲声源级仅与负载注入峰值功率有关,气泡脉冲声源级和气泡周期则主要受放电能量影响,多电极放电通过减小单根电极放的电能量来减小气泡脉冲声源级和气泡周期。此外,在相同的充电电压下,减小充电电容对电极数的比,可以增大直达波脉冲声源级并压制气泡脉冲;负载注入峰值功率对放电能量的比对声特性的影响也呈现出类似规律。实测及其分析结果可为进一步优化水下等离子体脉冲声源的声特性提供参考。 相似文献
11.
A study of sub-microsecond high voltage pulse excited glow discharges in atmospheric helium is carried out here. The discharge is generated between the powered copper electrode and ground electrode covered with a ceramic sheet. The electrical and optical characteristics of two discharge events in each voltage pulse in terms of discharge current amplitude, current pulse duration, time instant at current peak and accumulated charge in discharge are investigated on voltage pulse duration and pulse voltage magnitude. The time-resolved imaging with 5 ns exposure time is used to demonstration the spatio-temporal evolution of discharge. It is found that the first discharge depends markedly on pulse voltage magnitude and space charge accumulation on ceramic sheet surface plays an important role on ignition of second discharge. 相似文献
12.
冷阴极真空规应用时有较大的抽气作用,而且放电产生的热量和离子溅射对电极表面的污损也使其正常操作受到一定影响。为此,本文设计了一种智能脉冲高压电路,对一种反磁控冷阴极真空规(IMG)的脉冲放电测量模式、恒流放电测量模式及不同压强下的伏安特性等问题进行了实验研究。指出将低压强下的直流放电模式和较高压强时的脉冲放电模式结合起来是反磁控冷阴极真空规的一种较为合理的应用方法。 相似文献
13.
Tao Shao Cheng ZhangYang Yu Zheng NiuHui Jiang Jiayu XuWenfeng Li Ping Yan Yuanxiang Zhou 《Vacuum》2012,86(7):876-880
Dielectric barrier discharge driven by repetitive nanosecond pulses can offer highly efficient non-thermal plasma at atmospheric pressure and is widely used for plasma applications. In this paper, the discharge is generated using a compact pulsed power generator based on one-stage magnetic compression. The output pulse can be up to 30 kV with a rise time of about 40 ns and a full width at half maximum of 70 ns. The electrical characteristics of the discharge parameters are studied by the measurement of voltage and current waveforms. The effects of applied voltage amplitude, voltage polarity, pulse repetition frequency, and barrier dielectric on discharge characteristics are investigated, respectively. The experimental results show that the discharge current, discharge power and electron density increase with the increase of the applied voltage, and the pulse repetition frequency has a slight effect on the electrical parameters. Moreover, the discharge current is influenced by the dielectric barrier, but it is not varied with the polarity of applied pulses. 相似文献
14.
In this paper, the temporal nonlinear behaviors of pulsed dielectric barrier discharge in atmospheric helium are studied numerically by a one-dimensional fluid model. The results show that the common single-period pulsed discharge with two current pulses per single voltage pulse can take place over a broad parameter range. The rising and falling times of the voltage pulse can affect the discharge characteristics greatly. When the discharge is ignited by a pulse voltage with long rising and falling times, a single-period pulsed discharge with multiple current peaks can be observed. Under appropriate rising and falling times of the voltage pulse, a stable period-two discharge can occur over wide frequency and voltage ranges. Also this period-two discharge can exhibit different current and voltage characteristics with changing the duty cycle. With other parameters fixed, the pulsed DBD could be driven to chaos through period-doubling route by increasing either the falling time or the frequency of voltage pulse. 相似文献
15.
This paper reports the registered extinction curves of the longitudinal combined discharge in nitrogen when rf and dc voltages were applied to the same electrodes. The application of dc voltage is shown first to lead to an increase in the rf discharge extinction voltage; at the same time, the “cathode” sheath thickness increases and the number of charged particles in the plasma volume decreases. The discharge extinction curve first shifts to the range of higher rf voltage and gas pressure values, and the region of multi-valued dependence of the rf extinction voltage on gas pressure vanishes. At larger dc voltage values, when the “cathode” sheath breakdown occurs, the rf discharge extinction voltage decreases and approaches zero at the dc extinction voltage for the dc self-sustained discharge. 相似文献
16.
Conventionally, Marx generators are used for the production of short duration, high voltage pulses but since many discharge
gap switches are utilized for stepping up the voltage, there are many disadvantages. Here, an alternative and much simpler
technique for the multiplication of nanosecond high voltage pulses has been presented in which multiplication takes place
by switching single spark gap providing voltage gain of ‘nxV’ wheren is the subsequent number of stages. Stepped up high voltage pulse with fixed voltage gain of defined shape with fast rise
time and good flat top is produced without using additional pulse-forming network. Its operation has been made repetitive
by switching single spark gap. Multipurpose use, low cost, small size, light weight (weighing less than 50 kg) and portability
are the additional benefits of the system. The reported nanosecond pulser has been made by cascading three stages of Blumlein.
To cross check its performance the parasitic impedance of the system has been evaluated to realize its adverse effect on the
voltage gain and pulse shape. Also its operation has been simulated by PSPICE circuit simulator program and good agreement
has been obtained between simulated and experimental results. Applications of this pulse generator include X-ray generation,
breakdown tests, ion implantation, streamer discharge studies and ultra wideband generation, among others. 相似文献
17.
Ashurbekov N. A. Iminov K. O. Kobzev O. V. Kobzeva V. S. 《Technical Physics Letters》2010,36(8):766-769
The spatial structure of optical emission from a transverse nanosecond pulsed electric discharge with a hollow (slit) cathode
has been experimentally studied. A regular periodic plasma structure has been observed during nanosecond pulsed discharge
in helium at medium pressures. Conditions of the plasma structure formation with respect to the discharge voltage and current
are determined. It is shown that the observed plasma structure differs from the known types of striations. 相似文献
18.
I. D. Kostyrya V. M. Orlovskii V. F. Tarasenko A. N. Tkachev S. I. Yakovlenko 《Technical Physics Letters》2005,31(6):457-460
The phenomenon of electric breakdown in air at atmospheric pressure without additional preionization was studied by experimental
and theoretical methods. Using voltage pulses of different polarity with subnanosecond leading front and nanosecond width,
volume discharge can be obtained under such conditions between electrodes of various configurations, in particular, between
two point electrodes. The development of an ionization wave in nitrogen is described within the framework of a diffusion-drift
approximation in a spherical geometry. The fact that the qualitative character of discharge is independent of the voltage
pulse polarity is explained by the multiplication of background electrons in the high-density gas. 相似文献
19.
30kV高压脉冲电源及其废水降解电离试验 总被引:4,自引:0,他引:4
根据高压间隙放电的特性,设计了一种频率可调的高压脉冲电源.试验表明,高压脉冲电源输出电压可达30kV,频率范围为10~200Hz,应用于难降解有机废水的高压电离处理及与臭氧协同处理中,取得了较好的效果. 相似文献
20.
The laser ablation fast pulse discharge plasma spectroscopy (LA-FPDPS) technique has demonstrated its validity to enhance the optical emission of laser-induced plasma. It has the potential to improve the performance of traditional LIBS measurement. Very recently, LA-FPDPS with a nanosecond pulse discharge circuit has been developed, which has a better capability to enhance the optical emission intensity of laser plasma compared with that using a microsecond pulse discharge circuit. In this paper, the effect of the discharge capacitance and discharge voltage on the optical emission of soil plasma generated by LA-FPDPS with a nanosecond pulse discharge circuit is evaluated in detail. In addition, the stability of the time delay between the laser firing and discharge, and between the discharge and optical emission, has been carefully investigated. 相似文献