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101.
Plasma waves are oscillations of electron density in time and space, and in deep submicron field effect transistors, typical plasma frequencies, ωp, lie in the terahertz (THz) range and do not involve any quantum transitions. Hence, using plasma wave excitation for detection and/or generation of THz oscillations is a very promising approach. In this paper, the investigation of plasma wave interaction between the plasma waves propagating in a short-channel High-Electron-Mobility Transistor (HEMT) and the radiated electromagnetic waves was carried out. Experimentally, we have demonstrated the detection of the terahertz (THz) radiation by an AlGaAs/GaAs HEMT up to third harmonic at room temperature and their resonant responses show very good agreement with the calculated results. 相似文献
102.
Spinel cobalt ferrite, CoFe2−xMxO4 has been synthesized by substitution of the combination of metallic elements M=Zr–Mg by the microemulsion method using polyethylene glycol as a surfactant. Powder X-ray diffraction analysis reveals that the substitution results in shrinkage of the unit cell of cobalt ferrite due to higher binding energy of the synthesized samples. The energy-dispersive X-ray fluorescence analysis confirms the stoichiometric ratios of the elements present. The thermogravimetric analysis shows that the minimum temperature required for the synthesis of these substituted compounds is 700 °C. A two-point probe method was employed for the measurement of the electrical resistivity in a temperature range of 293±5 to 673±5 K. It appears that there is a decrease in the number of Fe2+/Fe3+ pairs at the octahedral sites due to the substitution and corresponding migration of some of the Fe3+ ions to tetrahedral sites, consequently increasing the resistivity and the activation energy of hopping of electron at the octahedral sites. The susceptibility data also suggest migration of Fe3+ to tetrahedral site in the initial stage, which results in an increase in A–B interactions leading to large increase in the blocking temperature (TB) as observed in samples having dopant content x=0.1. 相似文献
103.
讨论了静态非均匀磁场中的磁场旋度对带电粒子引导中心漂移的影响。运用三维矢量分析的方法,将带电粒子垂直于磁场运动所引起的磁场漂移分为两项,分别由磁场的曲率和磁场的旋度决定。给出了螺旋状环形磁场中由磁场旋度引起的磁场漂移的近似表达式,讨论了该漂移成分对于该磁场中通行粒子轨道和捕获粒子轨道的可能影响。结果表明,带电粒子垂直于磁场运动所引起的磁场漂移主要由磁场的曲率决定,而磁场旋度对该漂移的影响比较微弱。 相似文献
104.
105.
A theoretical investigation on amplification of electrostatic ion acoustic wave in magnetically confined plasma has been presented in this paper. This investigation considers nonlinear wave–particle interaction process, called plasma maser effect, in presence of drift wave turbulence supported by magnetically confined inhomogeneous plasma. The role of associated nonlinear dissipative force in this effect in a confined plasma has been analyzed. The nonlinear force, which arises as a result of resonant interaction between electrons and modulated fields, is shown to drive the instability. Using the ion fluid equation and the ion equation of continuity, the nonlinear dispersion relation of a test ion acoustic wave has been derived, and the growth rate of ion acoustic wave in presence of low frequency drift wave turbulence has been estimated using Helimak data. 相似文献
106.
In order to set up the precision limit that can be reached with laser-induced breakdown spectrometry microprobe, a steel sample was scanned by using a 6-µm diameter spot. Besides being close to the limit of the technique, such a spot diameter resulted in a small plasma size that minimized self-absorption effects. To minimize shot noise, Cr and Fe were used as test elements because of their high contents. Scan consisted of 25 successive matrices formed by 5 × 6 shots, i.e. a total of 750 shots. Results were studied as a whole, as well as between matrices and within matrices, to search for inhomogeneity, outliers and drift. Except a few outliers, the main contribution in the experimental RSD was the drift either within a matrix or between matrices. Drift attributed to laser warm up could be compensated for either by using a polynomial fitting or by using the other element. %RSD significantly below 2 were then obtained demonstrating that there is no penalty in terms of precision to perform laser microprobe using a series of single shots. 相似文献
107.
《Analytical letters》2012,45(9):1310-1320
Abstract The drift tube temperature of an evaporative light-scattering detector for inorganic anions and cations response has been evaluated. The results of the detector are independent of temperature in the range studied (40–80°C) for cations, sulfate, and phosphate, but the responses for chloride and nitrate decrease when tube temperature increases. We also studied the effect of nebulizing gas temperature on the response of the evaporative light-scattering detector and noted a 200% improvement of the intensity of the signal. 相似文献
108.
The following degenerate parabolic system modelling chemotaxis is considered:
(KS) 相似文献