共查询到20条相似文献,搜索用时 10 毫秒
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K. Kawahta T. Tetsuka J. Fujita M. Nagatsu H. Ohnishi S. Okajima T. Iwasaki 《Journal of Infrared, Millimeter and Terahertz Waves》1988,9(7):655-665
A 4-channel HCN laser scattering system has been developed and applied to the JIPP T-IIU tokamak. Main aim of this system is to study microturbulence excited in the plasma, especially in the high power ICRF heating experiment. The observed density fluctuations are in a frequency range of the electron diamagnetic drift wave and have broad frequency spectra. The main part of the wavenumber is found to satisfy the condition of \(k_ \bot \rho _i \lesssim 1\) . In the heating experiments, deterioration of the energy confinement time is observed, and the density fluctuation level increases with the increase of the heating power. 相似文献
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Electron density measurements are periormed on HT-6M tokamak using a 7 channel Far-Infrared HCN laser interferometer. From the measured line integrals--7 channel phase shifts the electron density profile is reconstructed by a fit procedure. Results were tested by comparison to Abel inverted. Some recent interesting experimental results were reported. 相似文献
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The statistics of the frequency of the bandpass filtered beat signal between a DFB-laser and an external cavity laser were measured. The distribution of frequency fluctuations from the centre frequency is shown to be very close to Gaussian, with the variance given by the product of beat signal linewidth and IF-filter bandwidth 相似文献
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Qiu Bingshen Luo Xizhang Zheng Xingshi Luo Yongjang 《Journal of Infrared, Millimeter and Terahertz Waves》1988,9(10):923-932
The influences on HCN laser frequency by the parameters of the laser have been discussed theoretically and experimentally. The frequency variations of the HCN laser versus discharge current and gas pressure have been measured to be 2.9 kHz/mA and 8.1 kHz/mtorr respectively. The experimental results have been explained theoretically. 相似文献
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O. Dumbrajs J. A. Heikkinen K. Sarparanta S. K. Sipilä K. Novik A. Piliya 《Journal of Infrared, Millimeter and Terahertz Waves》1995,16(1):307-315
The enhanced scattering diagnostics method based on the scattering of microwaves close to the upper hybrid resonance in the plasma has a high sensitivity and spatial resolution and makes it possible to observe the plasma density fluctuations with characteristic scale-lengths much smaller than the wavelength of the probing radiation in vacuum. Good spatial resolution for spatial positioning of the scattering volume by fast tuning of the source frequency ±5% around the reference frequency in the range 100–300 GHz at high power makes this diagnostic method particularly suitable for fluctuation and high energy particle measurements in tokamak plasmas with relatively flat density and temperature profiles. 相似文献
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激光薄膜的总积分散射测量 总被引:1,自引:1,他引:0
本文提出一种测量激光薄膜总积分散射的方法,并推导出其测量公式。给出了用光调制弱信号同步锁相技术的一些实验结果,装置的检测灵敏度优于10~(-5)。 相似文献
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We describe a method for measuring the frequency fluctuation spectrum of a laser oscillator, especially the weak noise contributions in the wings of the spectrum, and apply this method to confirm the existence of large excess quantum frequency fluctuations in a laser oscillator using an unstable optical resonator. Our measurement apparatus uses the Pound-Drever technique, which employs an RF phase modulator and a Fabry-Perot cavity to produce a sensitive high-speed frequency discrimination signal. We show that this signal can also be used to measure the quantum noise contributions to the frequency spectrum of a laser oscillator. Experimental measurements on a miniature diode-pumped Nd:YAG laser using a stable optical cavity closely match the predictions of the usual Schawlow-Townes theory, while the frequency fluctuations in a nearly identical laser employing an unstable optical resonator are approximately 1300 times larger. These much larger fluctuations arise in part from the larger output coupling and cavity bandwidth of the unstable cavity, but they also appear to confirm a predicted excess spontaneous emission factor (Petermann excess noise factor) of ≈180 times arising from the nonorthogonal transverse mode properties of the unstable cavity 相似文献
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为了利用激光散射分布测量表面粗糙度参数,从分析高斯粗糙表面非傍轴散射光能量的角分布特征与轮廓均方根斜率之间的关系,得到了利用散射角分布进行粗糙表面横向粗糙度参数的测量方法。提出了散射光的两个特征值:辐射立体角密度矩M(θ)和M(φ),用以表征散射光能量立体角分布情况,并给出了在非傍轴远场条件下的测量和计算方法。实验证明,给出的特征参数能够得到散射光能量立体角分布特征并可用于测量粗糙表面横向形貌参数。 相似文献
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迷彩涂层1064 nm激光散射特性对激光探测装备的极限作用距离和军事装备激光隐身性能有显著影响,而目前对涂层材料的激光散射特性的研究大都是针对单一种类涂层。本文根据不同类型迷彩涂层由不同颜色组成的特点,通过分别测量不同颜色迷彩涂层的双向反射分布函数(BRDF),再根据国军标中不同迷彩涂层颜色的面积比例规定进行加权计算,得到不同种类迷彩涂层的BRDF。以草原夏季型迷彩涂层为例,利用上述方法对其BRDF进行测量和计算,并利用五参数经验模型进行参数建模,得到草原夏季型迷彩涂层的参数模型。通过拼接实验,验证了计算方法的正确性。对于进一步研究军事装备的涂层材料激光散射特性提供数据依据,为研究类似情况下多种材料复合涂层的激光散射特性研究提供了借鉴思路。 相似文献
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Nagai S. Furuhashi H. Kono A. Uchida Y. Goto T. 《Quantum Electronics, IEEE Journal of》1998,34(6):942-948
Time-resolved number densities of electrons in a discharge-pumped ArF excimer laser are measured by an interferometric method. The peak electron density is 6.7×1015 cm-3 at a total gas pressure of 2.5 atom, a gas mixture ratio of F2-Ar-He=0.2-10.0-89.8, and a charging voltage of 24 kV for a 68-nF storage capacitor bank. The dependences of the electron density and laser output power on the Ar and F2 fractions in Ar-F2-He mixture and on the Ne-He mixing ratio in Ar-F2 -He-Ne mixture are investigated, and the effects of Ar-F2 -He-Ne mixing ratio on the ArF laser discharge are discussed. The experimental data of the peak electron density are also compared with the results of a computer simulation. A good agreement between them was obtained by considering the fact that the actual discharge volume occupied only part of the electrode width 相似文献
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G. Ichtchenko W. P. O'Connor M. Moresco E. Zilli 《Journal of Infrared, Millimeter and Terahertz Waves》1984,5(12):1543-1569
The scattering of 2 mm radiation by the density fluctuation associated with lower hybrid waves is used to localize the injected waves within a cross-section of the plasma. A translating antenna setup scores a region extending from the center of the plasma to the boundary with two fixed scattering angles. The measured amplitudes allow one to determine the local value of certain spectral components of n" in the plasma. 相似文献
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Measurement of the target scattering matrix 总被引:2,自引:0,他引:2