共查询到20条相似文献，搜索用时 15 毫秒
1.
汪兴康 毛文哲 谢锦林 兰涛 李弘 刘阿娣 周楚 温晓辉 卫子安 吴捷 陈晨 刘东宽 饶贤昊 蔡虎 邬佳仁 邓鹏 刘海庆 丁卫星 庄革 刘万东 《等离子体科学和技术》2024,28(3):034009-1-034009-5
A multi-channel polarimeter–interferometer has been developed on the Keda Torus eXperiment (KTX) for the study of equilibrium dynamics and internal magnetic fluctuations. A three-wave technique based on terahertz solid-state sources (~650 GHz) is applied for simultaneous measurements of electron density and Faraday rotation angle. The output power of the microwave source is 2 mW. Faraday rotation effect using a rotating wave plate is tested with phase noise less than 0.8°, and the density phase noise is less than 0.9°. Measurement of Faraday rotation angle and density for discharges on KTX have demonstrated high sensitivity to internal MHD activities. 相似文献
2.
In this study,we report a laser interferometry experiment for the online-diagnosing of a laserproduced plasma.The laser pulses generating the plasma are ultra-fast(30 femtoseconds),ultraintense(tens of Terawatt) and are focused on a helium gas jet to generate relativistic electron beams via the laser wakefield acceleration(LWFA) mechanism.A probe laser beam(λ?=?800 nm) which is split-off the main beam is used to cross the plasma at the time of arrival of the main pulse,allowing online plasma density diagnostics.The interferometer setup is based on the No Marski method in which we used a Fresnel bi-prism where the probe beam interferes with itself after crossing the plasma medium.A high-dynamic range CCD camera is used to record the interference patterns.Based upon the Abel inversion technique,we obtained a 3D density distribution of the plasma density. 相似文献
3.
With more than 30 years of development, laser-induced fluorescence(LIF) is becoming an increasingly common diagnostic to measure ion and neutral velocity distribution functions in different fields of studies in plasma science including Hall thrusters, linear devices, plasma processing, and basic plasma physical processes. In this paper, technical methods used in the LIF diagnostic, including modulation, collection optics, and wavelength calibration techniques are reviewed in detail. A few basic physical processes along with applications and future development associated with the LIF diagnostics are also reviewed. 相似文献
4.
Optical emission spectroscopy is a passive diagnostic technique,which does not perturb the plasma state.In particular,in a hydrogen plasma,Balmer-alpha(Hα) emission can be easily measured in the visible range along a line of sight from outside the plasma vessel.Other emission lines in the visible spectral range from hydrogen atoms and molecules can be exploited too,in order to gather complementary pieces of information on the plasma state.Tomography allows us to capture bi-dimensional structures.We propose to adopt an emission spectroscopy tomography for studying the transverse profiles of magnetized plasmas when Abel inversion is not exploitable.An experimental campaign was carried out at the Thorello device,a simple magnetized torus.The characteristics of the profile extraction method,which we implemented for this purpose are discussed,together with a few results concerning the plasma profiles in a simply magnetized torus configuration. 相似文献
5.
Monochromatic x-ray imaging is an essential method for plasma diagnostics related to density information. Large-field high-resolution monochromatic imaging of a He-like iron (Fe XXV) Kα characteristic line (6.701 keV) for laser plasma diagnostics was achieved using a developed toroidal crystal x-ray imager. A high-index crystal orientation Ge ⟨531⟩ wafer with a Bragg angle of 75.37° and the toroidal substrate were selected to obtain sufficient diffraction efficiency and compensate for astigmatism under oblique incidence. A precise offline assembly method of the toroidal crystal imager based on energy substitution was proposed, and a spatial resolution of 3–7 μ m was obtained by toroidal crystal imaging of a 600 line-pairs/inch Au grid within an object field of view larger than 1.0 mm. The toroidal crystal x-ray imager has been successfully tested via side-on backlight imaging experiments of the sinusoidal modulation target and a 1000 line-pairs/inch Au grid with a linewidth of 5 μ m using an online alignment method based on dual positioning balls to indicate the target and backlighter. This paper describes the optical design, adjustment method, and experimental results of a toroidal crystal system in a laboratory and laser facility. 相似文献
6.
Jelena PETROVIĆ Dragan RANKOVIĆ Miroslav KUZMANOVIĆ Jelena SAVOVIĆ Vasili KIRIS Alena NEVAR Mikhail NEDELKO Nikolai TARASENKO 《等离子体科学和技术》2023,62(4):045507-045507
Time-integrated optical emission analysis of laser-induced plasma on Teflon is presented. Plasma was induced under atmospheric pressure air using transversely excited atmospheric CO2 laser pulses. Teflon is a C-based polymer that is, among other things, interesting as a substrate for laser-induced breakdown spectroscopy analysis of liquid samples. This study aimed to determine the optimal experimental conditions for obtaining neutral and ionized C spectral lines and C2 and CN molecular band emission suitable for spectrochemical purposes. Evaluation of plasma parameters was done using several spectroscopic techniques. Stark profiles of appropriate C ionic lines were used to determine electron number density. The ratio of the integral intensity of ionic-to-atomic C spectral lines was used to determine the ionization temperature. A spectral emission of C2 Swan and CN violet bands system was used to determine the temperature of the colder, peripheral parts of plasma. We critically analyzed the use of molecular emission bands as a tool for plasma diagnostics and suggested methods for possible improvements. 相似文献
7.
本文介绍了基于托卡马克等离子体被动光谱诊断获得杂质密度的方法。通过被动光谱诊断测量获得杂质线辐射的空间多道弦积分强度分布,利用强度标定系数转换为绝对光亮度分布;通过测量弦与等离子体位形,将弦积分的强度分布反演变换为径向体发射率。根据线辐射强度激发截面求出对应电离态的离子密度,最后采用杂质输运程序模拟计算得出总密度分布。以东方超环(Experimental Advanced SuperconductingTokamak, EAST)托卡马克装置上软X射线-极紫外光谱(Soft X-ray and Extreme Ultraviolet Spectrometers, XEUV)诊断测量到的Mo XXIX-Mo XXXII为例,描叙了获得Mo杂质密度分布的过程,获得的总误差小于10%。 相似文献
8.
HU Liqun 《等离子体科学和技术》2011,13(1):125-128
A present status of the diagnostics in EAST is presented. As a very important step of the EAST project, tens of diagnostics were employed for operation and protection, plasma control and physics analysis to accommodate requirement for the study on plasma performance in EAST with upgraded RF power up to 4 MW (both LHCD and ICRF) in the forthcoming years. Recently, new diagnostics are set up to provide several profiles of key plasma parameters for the further evaluation and better understanding of the plasma performance and physics in EAST, including a 25-channel Thomson scattering system for density and electron temperature, a metal bolometry for radiated power, an X-ray crystal spectroscopy for both ion and electron temperatures and plasma rotation velocity, etc. It is expected that these diagnostics would play an important role in data analysis and interpretation combined with integrated modeling. 相似文献
9.
Modification of exposure conditions downstream in the diffusion chamber has been performed in helicon antenna-excited helium plasma by adjusting the magnetic field(intensity and geometry).In the inductively coupled mode(H mode), a reduction in ion and heat fluxes is found with increasing magnetic field intensity, which is further explained by the more highly magnetized ions off-axis around the last magnetic field lines(LMFL). However, in helicon wave mode(W mode), the increase in magnetic field intensity can dramatically increase the ion and heat fluxes.Moreover, the effect of LMFL geometry on exposure conditions is investigated. In H mode with contracting LMFL, off-axis peaks of both plasma density and electron temperature profiles shift radially inwards, bringing about a beam with better radial uniformity and higher ion and heat fluxes. In W mode, although higher ion and heat fluxes can be achieved with suppressed plasma cross-field diffusion under converging LMFL, the poor radial uniformity and a small beam diameter will limit the size of samples suitable for plasma irradiation experiments. 相似文献
10.
Diagnosis of Unmagnetized Plasma Electron Number Density and Electron-neutral Collision Frequency by Using Microwave 总被引：1，自引：0，他引：1
The plasma diagnostic method using the transmission attenuation of microwaves at double frequencies （PDMUTAMDF） indicates that the frequency and the electron-neutral collision frequency of the plasma can be deduced by utilizing the transmission attenuation of microwaves at two neighboring frequencies in a non-magnetized plasma. Then the electron density can be obtained from the plasma frequency. The PDMUTAMDF is a simple method to diagnose the plasma indirectly. In this paper, the interaction of electromagnetic waves and the plasma is analyzed. Then, based on the attenuation and the phase shift of a microwave in the plasma, the principle of the PDMUTAMDF is presented. With the diagnostic method, the spatially mean electron density and electron collision frequency of the plasma can be obtained. This method is suitable for the elementary diagnosis of the atmospheric-pressure plasma. 相似文献
11.
F. OgnissantoG. Gorini J. Källne L. BallabioM. Nocente M. Tardocchi 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(8):786-792
The cross section for d+3He elastic scattering has been determined for the angular range 20-180° (CM) for beam energies Ed = 0.05 to 11 MeV through combined use of experimental data, Coulomb scattering and extrapolations. The results are used to study, for instance, how the cross section is affected by nuclear interaction contributions. Implications of these results on the calculation of knock on effects in (3He)D plasmas subjected to RF heating and their manifestations in the spectrum of the d + d fusion neutron emission are discussed. 相似文献
12.
冯晓珍 《等离子体科学和技术》2003,5(4):1909-1914
The measuring principle and experimental results of the enthalpy probe technique for thermal plasma diagnostics are presented. Its calibration and errors are discussed. Typical results are presented for the system operation in an Ar/H2(5 % H2) plasma arc jet under a reactor chamber pressure of 101.3 kPa. The plasma temperature and velocity profiles are measured. The center temperature and velocity are 6600 K and 850 m/s for plasma power 9 kW at axial locationof 17 mm. 相似文献
13.
Interpreting experimental diagnostics data in tokamaks, while considering non-ideal effects, is challenging due to the complexity of plasmas. To address this challenge, a general synthetic diagnostics (GSD) platform has been established that facilitates microwave imaging reflectometry and electron cyclotron emission imaging. This platform utilizes plasma profiles as input and incorporates the finite-difference time domain, ray tracing and the radiative transfer equation to calculate the propagation of plasma spontaneous radiation and the external electromagnetic field in plasmas. Benchmark tests for classical cases have been conducted to verify the accuracy of every core module in the GSD platform. Finally, 2D imaging of a typical electron temperature distribution is reproduced by this platform and the results are consistent with the given real experimental data. This platform also has the potential to be extended to 3D electromagnetic field simulations and other microwave diagnostics such as cross-polarization scattering. 相似文献
14.
Hongming ZHANG 《等离子体科学和技术》2020,22(8):84001-084001
The dominant wavelength range of edge impurity emissions moves from the visible range to the vacuum ultraviolet(VUV) range, as heating power increasing in the Experimental Advanced Superconducting Tokamak(EAST). The measurement provided by the existing visible spectroscopies in EAST is not sufficient for impurity transport studies for high-parameters plasmas. Therefore, in this study, a VUV spectroscopy is newly developed to measure edge impurity emissions in EAST. One Seya-Namioka VUV spectrometer(McPherson 234/302) is used in the system, equipped with a concave-corrected holographic grating with groove density of 600 grooves mm~(–1). Impurity line emissions can be observed in the wavelength range ofλ=50–700 nm, covering VUV, near ultraviolet and visible ranges. The observed vertical range is Z=-350–350 mm. The minimum sampling time can be set to 5 ms under full vertical binning(FVB) mode. VUV spectroscopy has been used to measure the edge impurity emission for the 2019 EAST experimental campaign. Impurity spectra are identified for several impurity species, i.e., lithium(Li), carbon(C), oxygen(O), and iron(Fe). Several candidates for tungsten(W) lines are also measured but their clear identification is very difficult due to a strong overlap with Fe lines. Time evolutions of impurity carbon emissions of CII at 134.5 nm and CIII at97.7 nm are analyzed to prove the system capability of time-resolved measurement. The measurements of the VUV spectroscopy are very helpful for edge impurity transport study in the high-parameters plasma in EAST. 相似文献
15.
Linghan WAN Zhoujun YANG Ruobing ZHOU Xiaoming PAN Chi ZHANG Xianli XIE Bowen RUAN 《等离子体科学和技术》2017,19(2):25602-025602
The Q-band(33-50 GHz) fast sweep frequency modulated continuous wave(FMCW)reflectometry has been recently developed for electron density profile measurement on the Joint TEXT tokamak.It operates in ordinary mode(O-mode) with a 20 μs sweeping period,covering the density range from 1 × 10~(19) m~(-3) to 3 × 10~(19) m~(-3).On the bench test,a Yttrium Iron Garnet(YIG) filter is used for the dynamic calibration of the voltage controlled oscillator(VCO) to obtain a linear frequency sweep.Besides,the use of a power combiner helps to improve the sideband suppression level of the single side-band modulator(SSBM).The reconstructed density profiles are presented,which demonstrate the capability of the reflectometry. 相似文献
16.
A ns Nd:YAG pulsed laser has been employed to produce plasma from the interaction with a dense target, generating continuum and UV and soft x-ray emission depending on the laser parameters and target properties. The laser hits solid and gaseous targets producing plasma in high vacuum, which was investigated by employing a silicon carbide detector. The two different interaction mechanisms were studied, as well as their dependence on the atomic number. The photon emission from laser-generated plasma produced by solid targets, such as boron nitride(BN) and other elements(Al, Cu, Sn and Ta) and compounds such as polyethylene, has been compared with that coming from plasma produced by irradiating different gas-puff targets based on N_2 and other gases(Ar, Xe, Kr, SF_6). The experimental results demonstrated that the yields are comparable and, in both cases, increase proportionally to the target atomic number. The obtained results, focusing the attention on the advantages and drawbacks of the employed targets, are presented and discussed. 相似文献
17.
为满足国际热核聚变实验堆的宽量程中子通量测量需求,设计了基于FPGA和交流耦合平方积分的高性能数字化坎贝尔积分算法,拥有更强γ抑制能力的同时将中子甄别系统的测量范围从105 s-1提高到108 s-1。结合235U裂变室及坎贝尔测量原理研究了数字化坎贝尔积分算法,通过仿中子脉冲实验分析了脉冲甄别计数算法和坎贝尔积分算法重叠区域的工作性能,并得出坎贝尔积分算法在不同噪声下的适用条件,从而保证测量相对误差小于5%。使用基于该算法的测量系统在HL-2A进行了现场实验,对照脉冲甄别计数算法的测量结果进行标定,二者一致性非常好,在测量重叠范围内线性系数达0.97。 相似文献
18.
Chi-Shung YIP 《等离子体科学和技术》2020,22(8):85404
An algorithm for automated fitting of the effective electron temperature from a planar Langmuir probe I–V trace taken in a plasma with multiple Maxwellian electron populations is developed through MATLAB coding. The code automatically finds a fitting range suitable for analyzing the temperatures of each of the electron populations. The algorithm is used to analyze I–V traces from both the Institute of Plasma Physics Chinese Academy of Sciences’s Diagnostic Test Source device and a similar multi-dipole chamber at the University of Wisconsin–Madison. I–V traces reconstructed from the parameters fitted by the algorithm not only agree with the measured I–V trace but also reveal physical properties consistent with those found in previous studies. Cylindrical probe traces are also analyzed with the algorithm and it is shown that the major source of error in such attempts is the disruption of the inflection point due to both decreased signal-to-noise ratio and greater sheath expansion. It is thus recommended to use planar probes with radii much greater than the plasma Debye length when signal-to-noise ratio is poor. 相似文献
19.
《核技术(英文版)》2024,35(5):146-159
Currently,with the advent of high-repetition-rate laser-plasma experiments,the demand for online diagnosis for the X-ray spectrum is increasing because the laser-plasma-generated X-ray spectrum is very important for characterizing electron dynamics and applications.In this study,scintillators and silicon PIN(P-type-intrinsic-N-type semiconductor)diodes were used to construct a wideband online filter stack spectrometer.The X-ray sensor and filter arrangement was optimized using a genetic algorithm to minimize the condition number of the response matrix.Consequently,the unfolding error was sig-nificantly reduced based on numerical experiments.The detector responses were quantitatively calibrated by irradiating the scintillator and PIN diode with various nuclides and comparing the measured y-ray peaks.A prototype 15-channel spec-trometer was developed by integrating an X-ray detector with front-and back-end electronics.The prototype spectrometer could record X-ray pulse signals at a repetition rate of 1 kHz.Furthermore,an optimized spectrometer was employed to record the real-time spectra of laser-driven bremsstrahlung sources.This optimized spectrometer offers a compact solution for spectrum diagnostics of ultrashort X-ray pulses,exhibiting improved accuracy in terms of spectrum measurements and repetition rates,and could be widely used in next-generation high-repetition-rate high-power laser facilities. 相似文献
20.
This study presents the Langmuir and Faraday probe measurements conducted to determine the plume characteristics of the BUSTLab microwave electrothermal thruster (MET). The thruster, designed to operate at 2.45 GHz frequency, is run with helium, argon and nitrogen gases as the propellant. For the measurements, the propellant volume flow rate and the delivered microwave power levels are varied. Experiments with nitrogen gas revealed certain operation regimes where a very luminous plume is observed. With the use of in-house-built Langmuir probes and a Faraday probe with guard ring, thruster plume electron temperature, plasma density and ion current density values are measured, and the results are presented. The measurements show that MET thruster plume effects on spacecraft will likely be similar to those of the arcjet plume. It is observed that the measured plume ion flux levels are very low for the high volume flow rates used for the operation of this thruster. 相似文献