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1.
Zhen PENG 《等离子体科学和技术》2020,22(10):105601-105601
A multi-voltage probe array system is designed to measure the coupling resistance of an ioncyclotron resonance frequency antenna. In the process of the antenna coupling resistance dataextraction, the minimization algorithm, the original Levenberg–Marquardt algorithm, is replacedby the Broyden–Fletcher–Goldfarb–Shanno algorithm to achieve more stable and accurateresults. Moreover, a simple model of the multi-voltage probe array was applied to simulate theperformance of the Kalman filter, and to optimize the distance and position of the probes andprobe number to mitigate the influence of the system noise on the rebuilt results. During theEAST experiment in 2019, a four-voltage probe array was applied to measure the couplingresistance of line 6 during high confined mode discharge. The measurement results by the multi-voltage probe array system and the voltage/current probe pair show a good agreement. 相似文献
2.
CHEN Gen 《等离子体科学和技术》2016,18(8):870-874
The source system covering a working frequency range of 24 MHz to 70 MHz with a total maximum output power of 12 MW has already been fabricated for Ion Cyclotron Range of Frequency(ICRF) heating in EAST from 2012. There are two continuous wave(CW) antennas consisting of four launching elements each fed by a separate 1.5 MW transmitter. Due to the strong mutual coupling among the launching elements, the injection power for launching elements should be imbalance to keep the k||(parallel wave number) spectrum of the launcher symmetric for ICRF heating. Cross power induced by the mutual coupling will also induce many significant issues,such as an uncontrollable phase of currents in launching elements, high voltage standing wave ratio(VSWR), and impedance mismatching. It is necessary to develop a power compensation system for antennas to keep the power balance between the feed points. The power balance system consists of two significant parts: a decoupler and phase control. The decoupler helps to achieve ports isolation to make the differential phase controllable and compensate partly cross power. After that, the differential phase of 0 or π will keep the power balance of two feed points completely. The first power compensation system consisting of four decouplers was assembled and tested for the port B antenna at the working frequency of 35 MHz. With the application of the power compensation system, the power balance, phase feedback control, and voltage standing wave ratio(VSWR) had obviously been improved in the 2015 EAST campaign. 相似文献
3.
Two new ICRF antennas operating in the ion cyclotron radio frequency (ICRF) range have been developed for EAST to overcome the low coupling problem of the original antennas. The original ICRF antennas were limited in their power capacity due to insufficient coupling. The new antenna design takes into account both wave coupling and absorption processes through comprehensive wave coupling and absorption codes, with the dominant parallel wave number $ {k}_{//} $ of 7.5 m−1 at dipole phasing. Through the use of these new ICRF antennas, we are able to achieve 3.8 MW output power and 360 s operation, respectively. The initial experimental results demonstrate the reliability of the antenna design method. 相似文献
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杨宇晴 张新军 赵燕平 秦成明 程艳 毛玉周 杨桦 王健华 袁帅 王磊 琚松青 陈根 邓旭 张开 万宝年 李建刚 宋云涛 龚先祖 钱金平 张涛 《等离子体科学和技术》2018,20(4):45102-111
Recent ion cyclotron resonance frequency(ICRF) coupling experiments for optimizing ICRF heating in high power discharge were performed on EAST. The coupling experiments were focus on antenna phasing and gas puffing, which were performed separately on two ports of the ion cyclotron resonance heating(ICRH) system of EAST. The antenna phasing was performed on the I-port antenna, which consists of four toroidally spaced radiating straps operating in multiple phasing cases; the coupling performance was better under low wave number ∣k_‖∣(ranging from 4.5 to 6.5). By fuelling the plasma from gas injectors, placed as uniformly spaced array from top to bottom at each side limiter of the B-port antenna, which works in dipole phasing, the coupling resistance of the B-port antenna increased obviously.Furthermore, the coupling resistance of the I-port antenna was insensitive to a smaller rate of gas puffing but when the gas injection rate was more than a certain value(1021 s~(-1)), a sharp increase in the coupling resistance of the I-port antenna occurred, which was mainly caused by the toroidal asymmetric boundary density arising from gas puffing. A more specific analysis is given in the paper. 相似文献
6.
On the experimental advanced superconducting tokamak(EAST), a pair of voltage and current probes(V/I probes) is installed on the ion cyclotron radio frequency transmission lines to measure the antenna input impedance, and supplement the conventional measurement technique based on voltage probe arrays. The coupling coefficients of V/I probes are sensitive to their sizes and installing locations, thus they should be determined properly to match the measurement range of data acquisition card. The V/I probes are tested in a testing platform at low power with various artificial loads. The testing results show that the deviation of coupling resistance is small for loads RL??2.5 Ω, while the resistance deviations appear large for loads RL??1.5 Ω, which implies that the power loss cannot be neglected at high VSWR. As the factors that give rise to the deviation of coupling resistance calculation, the phase measurement error is the more significant factor leads to deleterious results rather than the amplitude measurement error. To exclude the possible ingredients that may lead to phase measurement error, the phase detector can be calibrated in steady L-mode scenario and then use the calibrated data for calculation under H-mode cases in EAST experiments. 相似文献
7.
The experimental advanced superconducting Tokamak has two suits of ion cyclotron radio frequency heating systems, in which the two antennas are of different structures. Their performance is assessed and compared by CST microwave studio. The radiating capacity of antennas and the arcing around them are estimated. The impurity release is analyzed by the radio frequency(RF) potential in the plasma sheath. The simulation results show that the radiating capacity for the folded antenna(I-port) is better than those for the double loops antenna(B-port). However,the folded antenna is worse than the double loops antenna in terms of breakdown. Moreover, the impurity production is relevant to spectrum shaping. The RF potential at(0, π,π, 0) phasing with the peak of spectrum k//= 8.5 m~(-1)is lower than the one with other phases. The impurity is reduced obviously when the folded antenna is powered with(0, π, π, 0) phasing. 相似文献
8.
Radio frequency (RF) heating in the ion cyclotron range of frequencies (ICRF) is one of the primary auxiliary heating methods for EAST. The ICRF system provides 6 MW power in primary phase and will be capable of 10 MW later. Three 1.5 MW ICRF systems in a frequency range of 25 to 70 MHz have already been in operation. The ICRF heating launchers are designed to have two current straps with each driven by a RF power source of 1.5 MW. In this paper a brief introduction of the ICRF heating system capability in EAST and the preliminary results in EAST are presented. 相似文献
9.
In numerical simulations of the ion cyclotron range of frequencies (ICRF) wave heating scheme, core solvers usually focus on wave propagation and absorption mechanisms within the core plasma region. However, the realistic scrape-off layer (SOL) plasma is usually simplified, making it difficult to have deeper understanding of wave propagation and absorption within the SOL. In this work, we employ a cold plasma assumption and an artificial absorption mechanism based on the approach of reference (Zhang et al 2022 Nucl. Fusion 62 076032), to study wave propagation and absorption in the realistic SOL plasma of the EAST. During the exponential decay of the total coupled power with respect to the toroidal mode numbers, several fluctuations are observed in the case of low collisional frequencies. The fluctuations may be caused by the cavity modes associated with specific toroidal mode numbers. Due to the presence of cut-off densities, the edge power losses and the total coupled power exhibit different behaviors before and after the cut-off layer is “open”. Furthermore, the simulation results obtained from the kinetic model in reference (Zhang et al 2022 Nucl. Fusion 62 076032) is discussed. This suggests that both the core-edge combined model and the artificial mechanism are capable of simulating wave propagation and absorption. 相似文献
10.
Manman XU Yuntao SONG Gen CHEN Yanping ZHAO Yuzhou MAO Guang LIU Zhen PENG 《等离子体科学和技术》2017,19(11):115601-115601
Ion cyclotron range of frequency(ICRF) heating has been used in tokamaks as one of the most successful auxiliary heating tools and has been adopted in the EAST. However, the antenna load will fluctuate with the change of plasma parameters in the ICRF heating process. To ensure the steady operation of the ICRF heating system in the EAST, fast ferrite tuner(FFT) has been carried out to achieve real-time impedance matching. For the requirements of the FFT impedance matching system, the magnet system of the ferrite tuner(FT) was designed by numerical simulations and experimental analysis, where the biasing magnetic circuit and alternating magnetic circuit were the key researched parts of the ferrite magnet. The integral design goal of the FT magnetic circuit is that DC bias magnetic field is 2000 Gs and alternating magnetic field is±400 Gs. In the FTT, E-type magnetic circuit was adopted. Ferrite material is Nd Fe B with a thickness of 30 mm by setting the working point of Nd Fe B, and the ampere turn of excitation coil is 25 through the theoretical calculation and simulation analysis. The coil inductance to generate alternating magnetic field is about 7 m H. Eddy-current effect has been analyzed, while the magnetic field distribution has been measured by a Hall probe in the medium plane of the biasing magnet. Finally, the test results show the good performance of the biasing magnet satisfying the design and operating requirements of the FFT. 相似文献
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Ping WANG 《等离子体科学和技术》2022,24(7):75103
Lithium Beam Emission Spectroscopy systems in the outer midplane and divertor Langmuir probe arrays embedded in the divertor target plates, are utilized to investigate the scrape-off layer (SOL) blob transition and its relation with divertor detachment on EAST. The blob transition in the near SOL is observed during the density ramp-up phase. When the plasma density, normalized to the Greenwald density limit, exceeds a threshold of fGW ∼ 0.5, the blob size and lifetime increases by 2 – 3 times, while the blob detection rate decreases by about 2 times. In addition, a weak density shoulder is observed in the near SOL region at the same density threshold. Further analysis indicates that the divertor detachment is highly correlated with the blob transition, and the density threshold of blob transition is consistent with that of the access to the outer divertor detachment. The potential physical mechanisms are discussed. These results could be useful for the understanding of plasma-wall interaction issues in future devices that will operate under a detached divertor and high density conditions (over the blob transition threshold). 相似文献
13.
Liang HE 《等离子体科学和技术》2022,24(6):64003
The measurement of impurity distribution in the divertor region of tokamaks is key to studying edge impurity transport. Therefore, a space-resolved vacuum-ultraviolet (VUV) spectrometer is designed to measure impurity emission in the divertor region on EAST. For good spectral resolution, an eagle-type VUV spectrometer with 1 m long focal length with spherical holograph grating is used in the system. For light collection, a collimating mirror is installed between the EAST plasma and the VUV spectrometer to extend the observing range to cover the upper divertor region. Two types of detectors, i.e. a back-illuminated charge-coupled device detector and a photomultiplier-tube detector, are adopted for the spectral measurement and high-frequency intensity measurement for feedback control, respectively. The angle between the entrance and exit optical axis is fixed at 15°. The detector can be moved along the exit axis to maintain a good focusing position when the wavelength is scanned by rotating the grating. The profile of impurity emissions is projected through the space-resolved slit, which is set horizontally. The spectrometer is equipped with two gratings with 2400 grooves/mm and 2160 grooves/mm, respectively. The overall aberration of the system is reduced by accurate detector positioning. As a result, the total spectral broadening can be reduced to about 0.013 nm. The simulated performance of the system is found to satisfy the requirement of measurement of impurity emissions from the divertor area of the EAST tokamak. 相似文献
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Mingxiang LU 《等离子体科学和技术》2022,24(9):95602
As an important component of tokamaks, the divertor is mainly responsible for extracting heat and helium ash, and the targets of the divertor need to withstand high heat flux of 10 MW m−2 for steady-state operation. In this study, we proposed a new strategy, using microchannel cooling technology to remove high heat load on the targets of the divertor. The results demonstrated that the microchannel-based W/Cu flat-type mock-up successfully withstood the thermal fatigue test of 1000 cycles at 10 MW m−2 with cooling water of 26 l min−1, 30 °C (inlet), 0.8 MPa (inlet), 15 s power on and 15 s dwell time; the maximum temperature on the heat-loaded surface (W surface) of the mock-up was 493 °C, which is much lower than the recrystallization temperature of W (1200 °C). Moreover, no occurrence of macrocrack and 'hot spot' at the W surface, as well as no detachment of W/Cu tiles were observed during the thermal fatigue testing. These results indicate that microchannel cooling technology is an efficient method for removing the heat load of the divertor at a low flow rate. The present study offers a promising solution to replace the monoblock design for the EAST divertor 相似文献
16.
The double tearing mode(DTM)in a high βN(βN>1.5)discharge with internal transport barrier on EAST was investigated.A 15 kHz tearing mode(TM)(m≥3,n=3)appears at outer q=2 surface at first,which is stable in the highβN phase.Then a 2 kHz TM(m=2,n=1)occurs at inner q=2 surface.Soon after,high βN collapsed with the crash of ELM,and DTM formed during the collapse of βN.The positions of the two islands of the DTM are consistent with the q=2 surface.The temperature fluctuations are the strongest between the two magnetic islands.A statistical analysis of high βN discharges operating with the reversed magnetic shear configuration in the EAST 2015-2018 campaign revealed the existence of the DTM in many discharges.During the DTM phase,all βN are reduced by 10%-30% within 0.1 s.However,there are two different βN behaviors thereafter-with and without βN recovery.Studying the physical mechanism of βN recovery during the DTM phase will benefit steady-state operation with reversed shear configurations in the future. 相似文献
17.
Liangsheng HUANG 《等离子体科学和技术》2022,24(2):25601
The Local Monte Carlo (LMC) method is used to solve the problems of deep penetration and long time in the neutronics calculation of the radial neutron camera (RNC) diagnostic system on the experimental advanced superconducting tokamak (EAST), and the radiation distribution of the RNC and the neutron flux at the detector positions of each channel are obtained. Compared with the results calculated by the global variance reduction method, it is shown that the LMC calculation is reliable within the reasonable error range. The calculation process of LMC is analyzed in detail, and the transport process of radiation particles is simulated in two steps. In the first step, an integrated neutronics model considering the complex window environment and a neutron source model based on EAST plasma shape are used to support the calculation. The particle information on the equivalent surface is analyzed to evaluate the rationality of settings of equivalent surface source and boundary. Based on the characteristic that only a local geometric model is needed in the second step, it is shown that the LMC is an advantageous calculation method for the nuclear shielding design of tokamak diagnostic systems. 相似文献
18.
Jong-Gu Kwak S.J. Wang J.S. Yoon Y.D. Bae S.K. Kim C.K. Hwang Sukkwon Kim Jose Sainz 《Fusion Engineering and Design》2009,84(7-11):1140-1143
KSTAR (Korea Superconducting Tokamak Advanced Research) is a national tokamak aiming at the high beta operation based on AT (Advanced Tokamak) scenarios in Korea and ICRF (Ion Cyclotron Ranges of Frequency) is one of the essential heating and current drive tools to achieve this goal. The ICRF heating and current drive scenario requires 4 units of 2 MW transmitters with a frequency range from 25 to 60 MHz. The first KSTAR transmitter is a modified FMIT (Fusion Material Irradiation Test) transmitter consisting of four amplifier stages. An amplitude-modulated 1 mW frequency source drives a 500 W solid state wideband amplifier, which in turn drives three tuned triode/tetrode amplifier stages. The tube employed in the final power amplifier is a 4CM2500KG tetrode fabricated by CPI (Communications & Power Industries). After the fabrication of the cavity and power supply was completed in 2004, several failures of the tube during a factory and a site acceptance test occurred before eventually achieving 1.9 MW for 300 s at 33 MHz in 2007. The electrical efficiency of the FPA (Final Power Amplifier) is about 70%. Although this is a very encouraging result for the development of an ICRF transmitter for ITER (International Thermonuclear Experimental Reactor), continued efforts for a reliable operation are required to achieve the final goals of the KSTAR and ITER ICRF system. 相似文献
19.
This paper reports for the first time an experimental study on the power deposition profile of the ion cyclotron range frequencies （ICRF） power depositing on electrons in HT-7. The fast Fourier transform （FFT） analysis and the break in slope （BIS） method are utilized to obtain the information of the power deposition. The results indicate that the electrons were heated directly, and the electrons absorbed around 20% of the input power of the discharge of interest. 相似文献
20.
Enhanced Plasma Performance by ICRF Boronization 总被引：1，自引：0，他引：1
Boronization with carborane(C2B10H12)by ICRF been applied routinely to the walls of HT-7 super-conducting tokamak for the reduction of impurity influx.especially carbon and oxygen.Significant suppression of metallic impurties and radiating power fraction are achieved.The imporved confinement for both particle and energy is observed in full range of operation parameters.Energy balance analysis shows that electron heat diffusion coefficient is strongly reduced.Measurements by Langmuir probes at the edge plasma show that poloidal velocity shear after boronization is changed to a profile to profile favoring to good confinement.The main emphasis of this paper is to describe effects of boronization on aspects of the enhanced plasma performance. 相似文献