共查询到20条相似文献,搜索用时 343 毫秒
1.
N. A. Ratakhin V. F. Fedushchak A. A. Erfort N. V. Zharova N. A. Zhidkova S. A. Chaikovskii V. I. Oreshkin 《Russian Physics Journal》2007,50(2):193-198
Radiography of short-living objects using X-pinch radiation is a new perspective direction in diagnostics developed at the
P. N. Lebedev Institute of Physics. High spatial (up to a few tenth of a micrometer) and temporal resolutions (up to 0.1 ns)
achieved with the use of the X pinch is extremely interesting to the researches of transient processes and substances in extreme
states. The X pinch is produced by two or more crossed wires (with wire diameters up to 30 μm) exploded under the influence
of current running through them. Scanning radiation is generated in a dense high-temperature plasma (up to several kiloelectron
volts) arising in the region of wire crossing. Among the main requirements on the generator used to create the X pinch are
current amplitudes of 150–300 kA and rates of current increase of 1–2 kA/ns. Up to now, these current pulse parameters have
been provided only by bulky stationary generators weighing from 300 kg to several tons. In the present paper, a small-size
(weighing 70 kg) high-current pulse generator (with current amplitude exceeding 300 kA and pulse rise time of 200 ns) of soft
x-ray radiation from high-temperature X-pinch plasma is described.
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Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 87–92, February, 2007. 相似文献
2.
The fine structure of a soft (0.8–3 keV) X-ray emitting zone in a 280 kJ neutron optimized plasma focus is investigated. Distinct continuous filaments are registered during the pinch phase. Time-resolved X-ray measurements show that the filamentation exists to ≈ 20–50 ns after the maximum compression. A comparison of these observations with those performed previously with a 56 kJ plasma focus device is also presented. 相似文献
3.
为了获得填充泡沫的钨丝阵动态黑腔动力学演化图像, 研究钨等离子体与泡沫柱的相互作用形式, 在1 MA脉冲功率装置上设计了四分幅紫外探针光(266 nm)阴影成像系统, 该系统时间分辨为2.5 ns, 静态空间分辨优于70 μm, 径向阴影图像展示了从固体丝膨胀消融到先驱等离子体与泡沫相互作用, 从泡沫的箍缩到反弹膨胀的全过程. 图像显示了在长约50 ns时间内丝等离子体以雨的形式持续与泡沫相互作用, 在整个箍缩阶段并未观察到等离子体壳层结构. 定量分析表明泡沫柱的最小箍缩速度为1.0×106 cm/s, 最大箍缩速度为6.0×106 cm/s, 在轴上滞止的直径约为1 mm. 通过对数值模拟计算结果的讨论, 明确了在Z箍缩等离子体状态下阴 影成像结果主要反映了逆轫致吸收效应, 与径向功率波形的时间关联给出了钨等离子体主体与泡沫柱相互作用时刻的图像.
关键词:
动态黑腔
阴影像
箍缩速度 相似文献
4.
A. G. Rousskikh A. V. Shishlov A. S. Zhigalin V. I. Oreshkin S. A. Chaikovsky R. B. Baksht 《Technical Physics》2010,55(11):1619-1627
The results of the experiments on the formation of a plasma emitter with small spatial dimensions for pulsed radiography in
the soft X-ray spectral range are presented. Emitting hot plasma was formed as a result of compression of the plasma jet by
a current pulse with amplitude I
m
= 215 kA and rise time T
fr = 200 ns. For the jet formation, we used a plasma gun based on the arc discharge (I
m
= 8.5 kA and T
fr = 6 μs) initiated by breakdown over the surface of a dielectric in vacuum. The experiments were carried out with aluminum,
tin, copper, and iron plasma jets. A single emitter, i.e., point Z-pinch (PZ-pinch), was formed when an interelectrode gap of a high current generator of 1.3–1.5 mm was used. The smallest spatial dimensions
of the emitting region were obtained with the use of aluminum and tin. For a tin jet, the diameter of the emitting region
was 7 ± 2 μm and its height was 17 ± 2 μm. The emission pulse duration at half-height was 2–3 ns. The total emission yield
per pulse in the spectral range 1.56–1.90 keV was 30–50 mJ for the aluminum pinch and 10–30 mJ for the tin pinch. The developed
method makes it possible to carry out radiographic examination of microobjects (including biological ones) 1–1000 μm in thickness,
with spatial (10–20 μm) and time (2–3 ns) resolution. 相似文献
5.
利用“阳”加速器对平行面多金属钨丝(直径17 μm,丝间距1 mm,丝数3根或5根)负载进行了Z箍缩聚爆实验研究。在峰值为350 kA,上升沿约80 ns的电流作用下,使用针孔成像技术和X射线诊断技术,获得多钨丝等离子体融合图像及相应的软X射线辐射信号。对金属丝聚爆过程中负载电流变化对实验影响进行了分析,并探讨了引起聚爆过程中的等离子体柱腊肠型不稳定性、扭曲型不稳定性和“热点”及其周围弥散斑等现象的原因。 相似文献
6.
We present here a very small transportable dense plasma focus with 125 J of energy able to be used mainly as an intense fast neutron source. The aim of this work was to design, construct and experimentally study a very compact nuclear fusion apparatus, at the lower energy limit, useful for multiple applications, such as soil humidity measurements, inspection of several materials metallic inclusions, medical neutron-therapies, etc. Besides, the possibility of using the same device as X-rays emitter has been explored. In a narrow range of deuterium filling pressure around 1 mbar, peaked Rogowski dips are observed. Correspondingly, strong neutron and hard X-ray pulses are measured. The neutron pulses last, in average, 50 ns, being about 106 the amount of neutrons per pulse. The performance of this device has shown to be higher than any other plasma focus apparatus, compar ed on the empirical scaling law of neutron yield vs. pinch current.Received: 29 April 2003, Published online: 5 August 2003PACS:
52.58.Lq Z-pinches, plasma focus and other pinch devices - 52.70.Ds Electric and magnetic measurements - 52.70.Nc Particle measurements 相似文献
7.
以"阳"加速器(1 MA,80 ns)驱动的Z箍缩等离子体为X射线源研究X射线加载下金属表面出现的电荷分离现象,Z箍缩负载为16根直径5μm的钨丝组成的丝阵,丝阵半径3 mm。强度107W/cm2、半高宽30 ns的软X射线脉冲通过直径5 mm的限光孔辐照半径30 mm、厚3 mm的铜盘中心,在金属表面产生了脉宽相近,幅值kV的电势。测量了该电势沿金属表面的分布,观测到微弱的调制现象。电势的极性表明电子主要沿金属表面运动而不是垂直表面运动,这表明热电效应是造成电荷分离的主要机制。入射X射线强度较弱时,电子的个体行为——光电效应、康普顿效应占主导;当入射强度较大时,弱关联的集体行为——热效应占主导;进一步增大入射X射线强度将出现强关联的集体行为——电荷密度调制状态。 相似文献
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9.
S. I. Tkachenko V. M. Romanova A. R. Mingaleev A. E. Ter-Oganesyan T. A. Shelkovenko S. A. Pikuz 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(2):335-341
Experimental results on electrical explosion of wires in vacuum with current density A/m2, current rise rate (dI/dt) ~ 50 A/ns and current pulse with amplitude ∼10 kA are presented. The structure of the discharge
channels in vacuum has been studied using laser shadow and schlieren imaging with 7 ns frames, UV pinhole images with 5 ns
frames and X pinch X-ray backlighting. The information on the dense core material and the conducting plasma distributions
was obtained in our experiments by analyzing and comparing the results obtained from all diagnostics. 相似文献
10.
Gyrokinetic simulations of small-scale turbulent transport in a closed magnetic field-line plasma geometry are presented. The simulations are potentially applicable to dipolar systems such as the levitated dipole experiment (LDX) [J. Kesner, Plasma Phys. Rep. 23, 742 (1997).] and planetary magnetospheres, as well as simpler systems such as the Z pinch. We report here for the first time the existence of a robust particle (and weaker temperature) pinch regime, in which the particles are transported up the density gradient. The particle pinch is driven by non-MHD entropy-mode turbulence at k(⊥) ρ(i) ~ 1 and particle pinch appears at larger η ≡ L(n)/L(T) ? 0.7, consistent with quasilinear theory. Our results suggest that entropy-mode transport will drive the LDX plasma profiles toward a state with η ~ 0.7 and pressure gradients that are near marginal ideal MHD interchange-mode stability. 相似文献
11.
“阳”加速器Z-Pinch实验中负载方案的分析 总被引:8,自引:6,他引:2
对“阳”加速器(1.2MV,1.5MA,120ns)上开展Z箍缩(Z-Pinch)内爆等离子体实验产生强X光源的负载设计进行了基本的物理分析,在此基础上给出负载的结构尺寸、气体种类、密度和相关的参数。这些结果对物理问题的分析是有帮助的. 相似文献
12.
《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2009,37(11):2191-2196
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丝阵负载内爆动力学行为基本可以分为以下四个过程:1)丝的烧蚀;2)壳层的形成;3)内爆;4)滞止.利用所研制的可见光分幅相机和X射线分幅相机在"强光一号"加速器上对多种型号的丝阵负载Z箍缩内爆动力学行为进行了实验研究,获得了从早期单丝烧蚀到等离子体柱崩毁全过程图像,并对实验结果进行了分析,主要研究成果如下:1)发现存在较长时间的丝烧蚀过程,且单丝烧蚀在轴向上并不均匀;实验得到的内爆轨迹与唯像模型计算结果较为一致.2)不论早期的可见光图像还是中后期的软X射线图像都存在明显的阴极发射,内爆后期在阴极附近存在明
关键词:
丝阵
内爆动力学
Z箍缩
脉冲功率技术 相似文献
17.
In this study the electron density of z‐pinch plasmas driven at relatively low currents (ca. 2‐5 kA) was determined using only emission spectroscopy. The suitability of a hollow‐cathode‐triggered z‐pinch plasma as an absorption medium for laser radiation was investigated. The temporal and spatial behaviors of electron temperature and density profiles were estimated using magnetohydrodynamic (MHD) simulations to evaluate the experimental results. Temperature measurements were performed according to the Boltzmann plot method in the visible spectrum range, using the fact that, in low‐current z‐pinch plasma, a local thermodynamic equilibrium prevails for states at high principal quantum numbers (partial local thermodynamic equilibrium). In this case, the Saha equation can be used to determine the electron density. The results demonstrate that this method of determining the electron temperature and density of z‐pinch plasmas is only applicable during the pinching phase. However, in this case the experimentally determined values are in fairly good agreement with the values determined using the MHD model. A user‐oriented 1‐D radiation MHD code was used to simulate the dynamic evolution of the plasma. The experimentally determined maximum electron temperature of approximately 12 eV is in fairly good agreement with the simulated value. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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P. I. Zubkov 《Technical Physics》1999,44(5):501-505
A dynamic model for plasma opening switches is proposed. The basis of the model is the appearance and development of force
instabilities (pinch and sausage) in a spatially nonuniform plasma accelerated by a magnetic field as a driver piston. The
proposed model does not require the invocation of subtle effects in the pinch collapse phase and makes it possible, without
going beyond the framework of magnetohydrodynamics, to explain the principal operating features of plasma opening switches
and to obtain quantitative estimates consistent with experiment.
Zh. Tekh. Fiz. 69, 25–29 (May 1999) 相似文献