共查询到20条相似文献,搜索用时 15 毫秒
1.
We present an improved structure of the tapered magnetically insulated transmission fine oscillator (MILO). Simulation results show that this structure can obtain more microwave power with higher efficiency. Studies indicate that the distance between the load support legs and the last vane can affect the operation characteristics of this device. In the experiments, we obtain microwave with peak power of 2 GW, frequency of 2.63 GHz, and mode TMol. The beam to microwave power efficiency is 11%. 相似文献
2.
A new configuration of an axially-extracted vircator with three resonant cavities is put forward and optimized by simulation with the PIC code. The output power of over 1 GW is obtained at around 4.1 GHz in the experiment, in agreement well with the PIC simulation results. The beam to wave power conversion efficiency is more than 6.6%. 相似文献
3.
Effects of Ion-to-Electron Mass Ratio on Electron Dynamics in Collisionless Magnetic Reconnection 总被引:3,自引:0,他引:3 下载免费PDF全文
A 2 1/2-dimensional electromagnetic particle-in-cell (PIC) simulation code is used to investigate electron behaviour in collisionless magnetic reconnectfon. The results show that the ion/electron mass ratio (mi/me) almost has no impact on the reconnection rate, however it can significantly affect electron behaviour in the diffusion region. For the case with larger mass ratio, the width of electron current sheet becomes smaller and the outflow region along the separatrix is smaller, hence the peak of the electron outflow speed is essentially larger. Density cavities and the parallel electric field E// along the separatrix can be found in the case with larger mass ratio, which may have significant influences on the acceleration and heating of the electrons near the X point. 相似文献
4.
Jinglong Tang Ling Xiong Jianyu Wang Jiage Li Tingfei Xi 《Applied Surface Science》2008,255(2):502-504
Nanosilver has been widely used in medical biology; however, the distribution and interaction of nanosilver with cells is still unclear. There have been some reports demonstrating that nanoparticles can cross the blood-brain barrier (BBB). The present study investigated the accumulation of silver nanoparticles in the brain, and the effects of silver nanoparticles on BBB. Nanosilver and microsilver (62.8 mg/kg) particles were subcutaneously injected into rats. The rats were sacrificed at predetermined time points and the brains were obtained for ultrastructural observation and silver level detection. The results showed that silver nanoparticles could traverse the BBB and move into the brain in the form of particle. The silver nanoparticles can induce neuronal degeneration and necrosis by accumulating in the brain over a long period of time. 相似文献
5.
S. I. Lashkul V. N. Budnikov A. D. Gurchenko E. Z. Gusakov V. V. Dyachenko L. A. Esipov E. R. Its M. Yu. Kantor D. V. Kouprienko K. M. Novik A. Yu. Popov V. L. Selenin A. Yu. Stepanov V. B. Yermolajev S. V. Shatalin E. O. Vekshina 《Czechoslovak Journal of Physics》2002,52(10):1149-1159
Experiments at the FT-2 tokamak had demonstrated effective plasma LH heating, which was accounted for by both direct absorption
of RF power and plasma transport suppression. The improved core confinement accompanied by Internal Transport Barrier (ITB)
formation was observed. The RF pulse switch off is followed by triggering of LH transition and the External Transport Barrier
(ETB) formation near the last closed flux surface. The present paper is devoted to a much more detailed study of the radial
electric fieldE
r behaviour in the region of ITB and ETB and its influence on the tokamak microturbulence in these regions. The new experimental
data were obtained by spatial spectroscopic technique using additional pulse helium puffing in hydrogen plasma. Simultaneously
microscale plasma oscillations in the frequency band (0.01–2) MHz are observed with local enhanced microwave scattering diagnostics
and by x-mode fluctuation reflectometry. Experiments demonstrate that the improved confinement is associated with the modification
of microturbulence by the shear of theE×B poloidal velocity. This conclusion is also confirmed by the data obtained by Langmuir probes in the edge plasma.
Presented at 5th Workshop “Role of Electric Fields in Plasma Confinement and Exhaust”, Montreux, Switzerland, June 23–24,
2002”.
The study was performed with the support of the Ministry of General and Professional Education of RF (TOO-7.4-2797), INTAS-01-2056
and the RFBR Grants 00-02-16927, 01-02-17926 and 02-02-17684. 相似文献
6.
Zernicke polynomials method was first used in HT-7 tomography. Combining the characteristics of the soft X-ray imaging system in HT-7 tokamak, some of the technical consideration in applicating the tomography method are reported in this Letter. Through analyzing experimental soft X-ray data of a typical discharge with m=1 mode superimposed on sawtooth, it is shown that in the mid-mode and precursor phases, the central magnetic surface structure is composed of a hot core and a small magnetic island. In the crash phase, the hot core is obviously pushed outside and evolves into a crescent. The magnetic island is large. In addition, we compared the reconstructions obtained with Zernicke polynomials method and the Fourier-Bessel expansion method. The comparison result shows that as the magnetic island is large, Zernicke polynomials method seems more suitable to reconstruct the central plasma emissivity distribution on HT-7 tokamak. At last, through analyzing the oscillation amplitude and island size of the m=1 mode superimposed on sawtooth, it is thought that the large oscillation amplitude is due to large pressure gradient at the vicinity of inversion surface. 相似文献
7.
8.
A Power Interruption Technique for Investigation of Temperature Difference in Stabilized Low Direct-Current Arc Burning in Pure Argon on Atmospheric Pressure 下载免费PDF全文
M. M. Kuzmanovic J. J. Savovic D. P. Rankovic M. Stoiljkovic A. Antic Jovanovic M.S. Pavlovic M. Marinkovic 《中国物理快报》2008,25(4):1376-1379
Plasma of argon stabilized arc column, in a current range 3-11 A, is investigated using emission spectrometric diagnostic techniques. Temperatures are evaluated using several methods: argon line to adjacent recombinational continuum intensity ratio, absolute emissivity of argon line, measurement of electron number density, and power interruption. Electron number density is evaluated from absolute emissivity of recombinational continuum. The difference between electron Te and heavy particle Th temperature ranged from 4500 K for 3 A to 2300 K for 11A arc current. By comparing the present with the previously obtained results, using the same arc device but with the introduction of water aerosol, it is concluded that water aerosol reduces the difference Te - Th and brings plasma closer to the partial thermodynamic equilibrium state. 相似文献
9.
Theoretical and Experimental Study of Scattering of a Plane Wave by an Inhomogeneous Plasma Sphere 下载免费PDF全文
Scattering of electromagnetic waves by an inhomogeneous plasma sphere has been studied theoretically and experimentally. The offset angles of electromagnetic waves caused by the plasma sphere have been observed experimentally. The effects of the electromagnetic wave frequency and plasma density on the offset angle are discussed. The plasma density is estimated with the offset angle. 相似文献
10.
We fabricate the hybrid films of colloidal CdSe/ZnS quantum dots (QDs) and poly(9-vinylcarbazole) (PVK) sandwiched between two electrodes. The voltage and temperature dependences of the electroluminescence (EL) are measured. The quantum-confined Stark effect of colloidal QDs is clearly observed. To explore the mechanism in the QD EL, hybrid films are fabricated with different concentrations of colloidal QDs. Electrons and holes are proposed to be separately transported in QDs and PVK, respectively. 相似文献
11.
大多数电容储能型脉冲功率装置的共同特点是采用了气体开关, 由于气体绝缘恢复的限制和电极的烧蚀, 使得其重复频率都不太高, 而且寿命有限. 而目前广泛研究的磁脉冲压缩技术在脉冲功率系统的长寿命、高平均功率和高重复频率运行方面具有很大的应用前景. 通过对BOOST电路、LC谐振电路和磁脉冲压缩电路详细的理论分析和计算机模拟, 设计了由BOOST电路, LC谐振电路, 脉冲变压器, 磁压缩系统, 负载五大部分组成的脉冲发生器电路系统模型, 使用Pspice软件对系统进行了模拟、优化, 得到了电压幅值为55kV, 脉宽为500ns的输出脉冲. 相似文献
12.
Experimental Investigation of Integrated Optical Intensive Impulse Electric Field Sensors 总被引:1,自引:0,他引:1 下载免费PDF全文
We design and fabricate an integrated optical electric field sensor with segmented electrode for intensive impulse electric field measurement. The integrated optical sensor is based on a Mach-Zehnder interferometer with segmented electrodes. The output/input character of the sensing system is analysed and measured. The maximal detectable electric field range (-75 kV/m to 245kV/m) is obtained by analysing the results. As a result, the integrated optics electric field sensing system is suitable for transient intensive electric field measurement investigation. 相似文献
13.
The impact of particle defects in the free propagation region on the performance of an etched diffraction grating demultiplexer is analyzed in the present paper. Numerical simulations using a method of moment and a Green function method show that particle defects with some special sizes can result in a strong resonance with the incident wavelength and will produce a large scattering loss. 相似文献
14.
15.
Dust lattice waves of a one-dimensional plasma crystal chain with an external magnetic field are investigated. When the magnetic field is in the vertical direction (θ- 0), perpendicular to the chain, the vertical transverse mode is not affected, while the horizontal transverse mode is coupled with the longitudinal mode. In the high frequency range, we obtain an ‘upper-hybrid' dust lattice mode and in the low frequency range, we obtain a 'lower-hybrid' dust lattice mode. Between the two modes, a 'gap' is formed. When the magnetic field is oriented to the chain (0 = π/2), the longitudinal mode is not affected while both the horizontal and vertical transverse modes are shifted due to the effect of the magnetic field. 相似文献
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18.
Xianbin Yu Xianmin Zhang Kangsheng Chen 《International Journal of Infrared and Millimeter Waves》2005,26(5):763-770
The filter frequency response and signal-to-noise ratio (SNR) capacity of fiber Bragg grating resonator based photonic microwave filter are investigated experimentally by using two lasers with different linewidths as optical sources. The effects of optical source on the photonic microwave filter performance are analyzed. The results show that when the laser linewidth is less than the filter free spectral range (FSR), the filter response is fluctuating and the SNR capacity decreases about 10dB. 相似文献
19.
M. Sharif S. Hussain M. Zakaullah A. Waheed 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,38(2):337-341
A 1.8 kJ Mather-type plasma focus (PF) for argon and hydrogen
filling is examined. Two anode configurations are used. One is tapered
towards the anode face, and the other is cylindrical but the face is cut at
different angles. At optimum conditions, the system is found to emit Cu–Kα
X-rays of about 1.6±0.1 J/sr in the side-on direction for argon
filling, which
is about 32% of the total X-ray emission. In 4π-geometry, maximum
total X-ray
yield and wall plug efficiency found are 26.4±1.3 J and 1.5±
0.1%
respectively. The modified geometry may help to use the PF as a radiation
source for X-ray diffraction. 相似文献
20.
Effect of Discharge Voltage on an Ion Sheath Formed at a Grid in a Multi-Dipole Discharge Plasma 下载免费PDF全文
M. K. Mishra A. Phukan 《中国物理快报》2008,25(3):1011-1014
It is experimentally demonstrated that a relatively strong ion-rich sheath formed at a fixed negative bias of the grid can be changed to a rather weak ion sheath (sheath potential weakly retards electrons) only by increasing the discharge voltage in the system. At sufficiently high negative grid bias, an increase of discharge voltage enhances the ion collection current at the grid. An explanation is put forward in support of this experimental observation. A slight density enhancement with a fall in plasma electron temperature is also observed with the increasing negative grid bias. 相似文献