The geometric form of the leader trajectory is an interesting aspect of long air gap discharge research. In this paper, the 3-D discharge channel tortuosity in 3m rod-plane gaps is obtained by following steps: Firstly...
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The geometric form of the leader trajectory is an interesting aspect of long air gap discharge research. In this paper, the 3-D discharge channel tortuosity in 3m rod-plane gaps is obtained by following steps: Firstly, using two static cameras fixed orthogonally to record the face photo and the side photo of the discharge channel. Secondly, the 3-D discharge channel is reconstructed by employing image recognition technology. Thirdly, the discharge channel tortuosity in two-dimensional space and three-dimensional space are derived respectively, which satisfied the Gaussian distribution law. The statistical results indicate that the channel tortuosity will be conservatively estimated by using a two-dimensional method. Statistical results of the channel tortuosity with three-dimensional method indicate the following conclusions. The angle between the discharge channel segments and the gap axis meets the distribution of rational function and its average value and standard deviation is 23.8° and ±19.0° respectively; the angle between the adjacent channel segments also meets the distribution of rational function, and its average value and standard deviation is 13.3° and ±9.9°.
A wide-viewing-angle visible light imaging system (VLIS) was mounted on the Joint Texas Experimental Tokamak (J-TEXT) to monitor the discharge process. It is proposed that by using the film data recorded the plasm...
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A wide-viewing-angle visible light imaging system (VLIS) was mounted on the Joint Texas Experimental Tokamak (J-TEXT) to monitor the discharge process. It is proposed that by using the film data recorded the plasma vertical displacement can be estimated. In this paper installation and operation of the VLIS are presented in detailed. The estimated result is further compared with that measured by using an array of magnetic pickup coils. Their consistency verifies that the estimation of the plasma vertical displacement in J-TEXT by using the imaging data is promising.
A soft X-ray pulse height analysis (PHA) system has been designed and installed on J-TEXT tokamak for the study of electron temperature and *** system contains three Silicon Drift Detectors (SDD),a multi-channel analy...
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A soft X-ray pulse height analysis (PHA) system has been designed and installed on J-TEXT tokamak for the study of electron temperature and *** system contains three Silicon Drift Detectors (SDD),a multi-channel analyzer (MCA),vacuum chamber,data collection procedure and off-line data processing program.A 60ms temporal resolution of electron temperature and the line radiation from moderate and high Z metallic impurities can be obtained by PHA *** on this SyStcm the performances of electron temperature and impurity have been investigated in J-TEXT ohmic heated plasmas.
The metalized film capacitor can work under a high electric field due to its self-healing characteristic. But when the capacitor is charged rapidly to a specified high voltage (under a high electric field) and then it...
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ISBN:
(纸本)9781457709852
The metalized film capacitor can work under a high electric field due to its self-healing characteristic. But when the capacitor is charged rapidly to a specified high voltage (under a high electric field) and then it is disconnected from the power supply, a significant voltage drop will be observed, so the capacitor energy efficiency will reduce. It can be observed that the general curve of the voltage decay has a rapid initial drop and then the curve can usually be fit to a pure exponential. Firstly, this paper analyses the factors which cause the voltage decay through experimental study. The research results show that electric field strength, operating temperature and hold time play important roles in the voltage decay process. The higher the electric field or operating temperature is, the more significant the voltage drop is. If the voltage of the capacitor is maintained for a specified period of time, the voltage drop will reduce significantly. Through these experimental results, it is revealed that the voltage drop is mainly related to leakage and polarization. So the insulation resistance at various temperatures under high electric field is tested by the special technique. The results of insulation resistances are consistent with the voltage decay at various temperatures. Moreover, the interfacial polarization which exists in the charging process of metalized film capacitor is discussed. The interfacial polarization causes the rapid initial voltage decay.
The principle of surface wave plasma discharge in a rectangular cavity is introduced simply based on surface plasmon polariton theory. The distribution of surface-wave electric field at the interface of the plasma-die...
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The principle of surface wave plasma discharge in a rectangular cavity is introduced simply based on surface plasmon polariton theory. The distribution of surface-wave electric field at the interface of the plasma-dielectric slab is investigated by using the three-dimensional finite-difference time-domain method (3D-FDTD) with different slotantenna structures. And the experimental image of discharge with a novel slot antenna array and the simulation of the electric field with this slot antenna array are both displayed. Combined with the distribution of surface wave excitation and experimental results, the numerical simulation performed by using 3D-FDTD is shown to be a useful tool in the computer-aided antenna design for large area planar-type surface-wave plasma sources.
Raman spectroscopy is a powerful and effective technique for analyzing and identifying the chemical composition of a substance. In this paper, we focus on supervised methods for estimating Raman spectra and present a ...
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Raman spectroscopy is a powerful and effective technique for analyzing and identifying the chemical composition of a substance. In this paper, we focus on supervised methods for estimating Raman spectra and present a supervised method that can handle rank deficiency for estimating the Raman spectra. Earlier work has mostly assumed that the reference spectra matrix whose columns consist of the library of reference spectra are of full rank. However in practice, methods that can handle rank deficient cases, and the special case of an over complete library, are needed. We present our theoretical discovery that the active set method with a proper starting vector can actually solve the rank deficient nonnegativity-constrained least squares problems without ever running into rank deficient least squares problems during iterations. Experimental results illustrate the effectiveness of the proposed approaches.
The J-TEXT tokamak is a complex experiment facility. Its running refers many subsystems, such as various power supply systems, a gas puffing system, many diagnostic systems, a safety protection system, etc. So it asks...
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ISBN:
(纸本)9781424435623
The J-TEXT tokamak is a complex experiment facility. Its running refers many subsystems, such as various power supply systems, a gas puffing system, many diagnostic systems, a safety protection system, etc. So it asks for a control system to manage the process of discharge. This paper presents the functions of control system for the J-TEXT tokamak, describes its structure, and introduces the realization based on QNX real time operating system. Results obtained demonstrate that the control system handles the discharge process perfectly. However, it will be continued to improve to meet much more requirement and get more perfect performance.
An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is ...
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An estimation method of plasma density based on surface plasmons theory for surface-wave plasmas is proposed. The number of standing-wave is obtained directly from the discharge image, and the propagation constant is calculated with the trim size of the apparatus in this method, then plasma density can be determined with the value of 9.1 × 10^17m^-3. Plasma density is measured using a Langmuir probe, the value is 8.1 × 10^17m^-3 which is very close to the predicted value of surface plasmons theory. Numerical simulation is used to check the number of standing-wave by the finite-difference time-domain (FDTD) method also. All results are compatible both of theoretical analysis and experimental measurement.
TEM cells or GTEM cells can be used to evaluate the radiated emissions of integrated circuits (ICs). The applicable frequency bandwidth of a TEM cell is limited due to the resonances of higher order modes. This paper ...
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