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1.
高气压强电场电离过程中的离子浓度分布规律   总被引:9,自引:0,他引:9  
研究了高气压强电场电离区域的离子浓度分布的连续性方程,对电离区域的电离物的产生、消失和输运进行了研究。通过采用电离放电增加了输入能量密度、G值、电离占空比等,从而提高了离子产生率。通过外加电场和离子“雪崩”头部的本征电场的叠加作用,离子被束缚在放电通道中。对离子施加垂直电场方向的作用力,就能把电场中的等离子体成束输送出去。已经能够做到有效体积仅为1cm3的等离子体源,输运等离子体率达到1012cm-3.s-1。  相似文献   

2.
利用系综MonteCarlo法研究了2H ,4H 和6HSiC的电子输运特性.在模拟中考虑了对其输运过程有着重要影响的声学声子形变势散射、极化光学声子散射、谷间声子散射、电离杂质散射以及中性杂质散射.通过计算,获得了低场下这几种不同SiC多型电子迁移率同温度的关系,并以4H SiC为例,重点分析了中性杂质散射的影响.最后对高场下电子漂移速度的稳态和瞬态变化规律进行了研究.将模拟结果同已有的实验数据进行了比较,发现当阶跃电场强度为1 0×106V·cm-1时,4H Sic电子横向瞬态速度峰值接近3 3×107cm·s-1,6H Sic接近3 0×107cm·s-1.  相似文献   

3.
在太阳核心的条件下 ,7Be原子被完全电离 .所以 ,重新计算的7Be和8B太阳中微子流强分别约为 4 0 0× 1 0 9cm- 2 ·s- 1和 6 1 8× 1 0 6 cm- 2 ·s- 1,而标准太阳模型预言的7Be和8B太阳中微子流强则分别是 4 80× 1 0 9cm- 2 ·s- 1和 5 1 5×1 0 6 cm- 2 ·s- 1.这将进一步增大在SuperKamiokande太阳中微子实验上中微子流强的实验测量值与理论预计值之间的差异 .  相似文献   

4.
闪电放电通道等离子体成分及相关特性的研究   总被引:3,自引:0,他引:3  
以无狭缝摄谱仪获得了青海和西藏地区的云对地闪电回击过程的光谱,依据谱线波长和相对强度等信息,结合等离子体相关理论,得到了放电通道温度和电子密度;在此基础上,根据Saha方程、电荷守恒方程和粒子数守恒方程计算了闪电通道主要元素各级电离的离子数密度,进而得到通道质量密度、压强及平均电离度,并分析了不同强度闪电放电通道的电离度、粒子数密度及其分布特征.结果表明:回击通道接近于完全电离,一次电离离子占主要地位,且NⅡ离子数密度最高;不同强度的闪电放电通道中,NⅡ和OⅡ离子的相对浓度值变化不大;计算过程中考虑带电离子间库仑相互作用以后,原子电离能的计算值降低,中性原子以及一次电离离子数密度的计算值变小,高次电离离子数密度的计算值变大.  相似文献   

5.
HT-6M托卡马克装置杂质输运   总被引:1,自引:0,他引:1       下载免费PDF全文
徐伟  万宝年  谢纪康 《物理学报》2003,52(8):1970-1978
利用多道可见光谱探测系统和近紫外转镜系统测量了HT-6M托卡马克等离子体中杂质的时空分布.建立完备的杂质输运程序,数值模拟碳、氧杂质在欧姆放电时的输运行为,得出了杂质的扩散和对流系数、不同电离态杂质离子密度、辐射功率密度和有效电荷数的空间分布. 分析低混杂波电流驱动(LHCD)期间杂质行为,结果表明等离子体粒子约束、杂质约束和能 量约束提高,辐射功率和有效电荷数减小. 关键词: 托卡马克 杂质输运 扩散系数 对流系数  相似文献   

6.
高剂量的磷离子注入4H-SiC(0001)晶面,注入速率从1.0×1012到4.0×1012 P+ cm-2s-1变化,而注入剂量固定为2.0×1015 P+ cm-2。室温注入,1500oC的高温下退火。利用光荧光和拉曼谱分析注入产生的晶格损伤以及退火后的残余缺陷。通过霍耳测试来分析注入层的电学性质。基于上述测试结果,发现通过减小磷离子的注入速率,极大地减少了注入层的损伤及缺陷。考虑到室温注入以及相对较低的退火温度(1500 oC),在注入速率为1.0×1012 P+ cm-2s-1及施主浓度下为4.4×1019 cm-3的条件下,获得了非常低的方块电阻106 Ω/sq。  相似文献   

7.
获得了6-甲基吲哚的单色共振多光子电离和双色共振多光子电离光谱,发现了在电子激发态的较强的CH3的转动谱线.根据理论计算对观察到的激发态光谱进行了标识,确定了更准确的电离能为60967±5cm-1.  相似文献   

8.
用脉冲直流放电产生Xe原子亚稳态5p56s[3/2]2和5p56s′[1/2]0.在单光子28000-42000cm-1能量范围内,结合飞行时间质谱技术获得Xe原子共振增强激发光谱.光谱分析表明,所有谱线来源于Xe原子5p56s[3/2]2和5p56s′[1/2]0两个亚稳态吸收单个光子向偶宇称np′、nf′自电离Rydberg态序列的跃迁.实验观测到许多新的自电离能级,并获得更精确和系统的能级位置和量子亏损值数据.  相似文献   

9.
用脉冲直流放电产生Xe原子亚稳态5p56s[3/2]2和5p56s′[1/2]0.在单光子28000-42000cm-1能量范围内,结合飞行时间质谱技术获得Xe原子共振增强激发光谱.光谱分析表明,所有谱线来源于Xe原子5p56s[3/2]2和5p56s′[1/2]0两个亚稳态吸收单个光子向偶宇称np′、nf′自电离Rydberg态序列的跃迁.实验观测到许多新的自电离能级,并获得更精确和系统的能级位置和量子亏损值数据.  相似文献   

10.
在 76 4 0 0~ 796 5 0cm-1的能量范围内测量了三氯乙烯的真空紫外脉冲场电离 光电子 (VUV PFI PE)谱 .根据量子化学理论计算的频率以及Franck Condon因子 ,对VUV PFI PE谱的振动谱带进行了标定 ,确认了11个三氯乙烯阳离子的振动频率 ,分别为 :ν1+ =14 8cm-1,ν2 + =180cm-1,ν3 + =2 86cm-1,ν4+ =4 0 2cm-1,ν5+=4 72cm-1,ν6+ =6 6 0cm-1,ν7+ =875cm-1,ν8+ =990cm-1,ν9+ =10 38cm-1,ν10 + =12 6 7cm-1,ν11+ =14 0 8cm-1.这些测量和新近用真空紫外 红外光诱导电离确定的ν12 + =30 73cm-1一起 ,提供了三氯乙烯阳离子电子基态的所有 12个振动频率的实验值 .通过对VUV PFI PE谱 (0 ,0 )跃迁带的光谱拟合 ,确定了三氯乙烯的电离能为(76 4 4 1.7± 2 .0 )cm-1((9.4 776± 0 .0 0 0 2 )eV) .  相似文献   

11.
研制了一套等效噪声吸收可达3×10-9cm-1的连续波光腔衰荡光谱装置。用该装置对介质阻挡放电等离子体中的OH自由基和水进行了原位定量测量,考察了OH自由基数密度随气压和放电电压以及放电频率的变化情况。实验结果表明,在(2.13~22.0)Χ103Pa范围内,随着气压增加,OH自由基数密度在气压较低时增加;而在较高气压时由于H2O的解离吸附作用使得体系中电子密度减小,OH自由基数密度随之减小。随放电电压和放电频率增加介质阻挡放电等离子体中电子密度和电子能量增加而导致OH数密度增加。  相似文献   

12.
Minimization of energy consumed in plasma generation is critical for applications, in which a large volume of plasmas is needed. We suggest that a high electron density atmospheric pressure plasmas can be generated by pulsed discharges in potassium seeded argon at an elevated temperature with a very small power input. The ionization efficiency and power budget of pulsed discharges in such plasmas are analytically studied. The results show that ionization efficiency of argon, especially at small reduced electric field E/N (the ratio of the electric field to the gas number density), is improved effectively in the presence of small amount of potassium additives. Power input of pulsed discharge to sustain a prescribed average level of ionization in potassium seeded argon is three orders of magnitude lower than that in pure argon. Further, unlike in pure argon, it is found that very short high-voltage pulses with very high repetition rates are unnecessary in potassium seeded argon. A pulse with lOOns of pulse duration, 5kHz of repetition rate, and 2Td (1 Td = 1 × 10^-21 Vm^2) of E/N is enough to sustain an electron density of 10^19 m^-3 in 1 arm 1500K Ar+0.1% K mixture, with a very small power input of about 0.08 × 10^4 W/m^3.  相似文献   

13.
14.
Monte Carlo simulation and Boltzmann equation solutions have been used to study the electron kinetics. All electronic excitation of SF6 is assumed to be dissociative in analogy with the known product channels in ionization and multiphoton dissociation. The electric-field-to-gas-density ratios are high (E/n ? 1000 Td, where 1 Td (Townsend) = 1 × 10-17 V . cm2) in low-pressure (p < 0.3 torr) radiofrequency (RF) discharges. At these high E/n values, the electron energy relaxation time is much shorter than the 74-ns period at 13.56 MHz. Furthermore, the time scale of the chemical kinetics is much longer than the period of the applied RF voltage. Therefore the electron energy distribution can "track" the time-varying electric field, and time- and space-averaged rate coefficients can be used in chemical kinetics models. A rate equation model has been used to study the chemical kinetic processes. Electron-impact dissociation and ionization are the dominant sources of chemically active species. An electron density of 1 × 108 cm-3 is estimated from the known average values of E/n and the discharge input power. Two limiting cases are studied for the positive and negative ion diffusion losses: a) trapped negative ions and positive ion loss at the ambipolar diffusion rate; and b) positive and negative ion losses at the free diffusion rates. Neutral particle diffusion losses are estimated by using an effective diffusion length which takes surface reflection into account and increases as the surface reflection probability increases.  相似文献   

15.
随着我国电力技术的迅猛发展,因电弧/电晕放电造成高压设备损坏、高压线传输损耗的问题愈加引起重视。完成了电弧/电晕目标在200~1 000 nm的光谱特性测量,发现电弧电晕光谱强度分布主要集中在200~400 nm紫外波段。提出了使用紫外面阵成像技术用于探测研究电弧/电晕的方法,通过一套自制的紫外面阵成像系统,成功实现了对高压电弧/电晕目标进行的实验室内紫外成像,以及氙灯积分球辐射定标与目标反演。实验结果表明,该套紫外面阵成像系统可用于对电弧电晕放电进行实时检测。该研究验证了电弧/电晕的紫外辐射特性,在距离2 m处得到反演后的6 kV电弧的紫外240~280 nm波段的辐照度为3.39×10-5 W·cm-2,为深入开展电弧/电晕的紫外特性研究提供强有力的依据。  相似文献   

16.
圆筒状DBD放电特性模拟研究   总被引:1,自引:0,他引:1  
用XOOPIC软件对同轴圆筒状反应装置DBD放电特性进行了二维模拟研究。在频率为20kHz、正弦电压幅值为5kV的大气压氩气放电中,再现了微放电通道形成和发展过程,其微放电的寿命约为4ns。获得了电子、离子、介质表面电荷密度和电场强度随空间和时间的分布,发现在高压线圈的位置附近电子、离子和介质表面电荷密度存在极值。与典型平板介质阻挡放电相比,微放电中的电子密度、场强增加2~3个数量级。  相似文献   

17.
A performance analysis is presented for the hydrogen dissociator used in hydrogen masers to provide a beam of atomic hydrogen. An analysis of the discharge characteristics yields relations for electron temperature as a function of vessel size and gas pressure and for plasma density as a function of power input. Also a relation between ion impact energy at the wall and electron temperature is derived. For a typical dissociator (2" diameter, 0.1 Torr hydrogen pressure, and 4 watt input power) these relationships yield an electron temperature of 39,000°K, a plasma density of 1011 cm-3 and an ion impact energy of 20 volts. The dissociation rate is calculated using published cross-sections. Assuming a recombination rate of 4 × 10-3, the analysis yields an atomic hydrogen density of about 1014 cm-3, a degree of dissociation of 2%, and an atomic beam flux of 1.3 × 1018 cm-2 × sec-1 for the example quoted. This beam flux is in good agreement with estimated values for hydrogen masers. A coefficient for performance ? is derived for the hydrogen dissociator, defined as the ratio of atomic beam flux to discharge power consumption. It is shown that ? is a function of the electron temperature and has a maximum at 87,000°K. It is concluded from this analysis that the discharge in presently used hydrogen dissociators is well optimized given the pressure constraints of the system.  相似文献   

18.
开发了氮空心阴极放电PIC/MC二维自洽模型。研究了N2传统空心阴极向微空心阴极放电转变过程中电势和电场的变化。结果表明,不同尺寸的空心阴极放电的电势及电场分布规律几乎类似,但空心阴极孔径减小且气压增加时,电场近似线性增加;典型微空心阴极电场比传统空心阴极放电电场约大3个量级;微空心阴极放电产生的电子,氮分子离子和氮原子离子的密度比传统空心阴极放电约大3个量级,且微空心阴极放电中,N2+密度比N+密度大8倍以上。  相似文献   

19.
Exact partial solutions are found for the electric field distribution in the outer region of a stationary unipolar corona discharge from an ideal conical needle in the space-charge-limited current mode with allowance for the electric field dependence of the ion mobility. It is assumed that only the very tip of the cone is responsible for the discharge, i.e., that the ionization zone is a point. The solutions are obtained by joining the spherically symmetric potential distribution in the drift space and the self-similar potential distribution in the space-charge-free region. Such solutions are outside the framework of the conventional Deutsch approximation, according to which the space charge insignificantly influences the shape of equipotential surfaces and electric lines of force. The dependence is derived of the corona discharge saturation current on the apex angle of the conical electrode and applied potential difference. A simple analytical model is suggested that describes drift in the point-plane electrode geometry under saturation as a superposition of two exact solutions for the field potential. In terms of this model, the angular distribution of the current density over the massive plane electrode is derived, which agrees well with Warburg??s empirical law.  相似文献   

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