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Cunkai LI, Yunfeng LIANG, Zhonghe JIANG, Song ZHOU, Jiankun HUA, Jie YANG, Qinghu YANG, Alexander KNIEPS, Philipp DREWS, Xin XU, Feiyue MAO, Wei XIE, Yutong YANG, Jinlong GUO, Yangbo LI, Zhengkang REN, Zhipeng CHEN, Nengchao WANG, the J-TEXT Team. Characteristics of the SOL ion-to-electron temperature ratio on the J-TEXT tokamak with different plasma configurations[J]. Plasma Science and Technology, 2024, 26(2): 025101. DOI: 10.1088/2058-6272/ad0c1e
Citation: Cunkai LI, Yunfeng LIANG, Zhonghe JIANG, Song ZHOU, Jiankun HUA, Jie YANG, Qinghu YANG, Alexander KNIEPS, Philipp DREWS, Xin XU, Feiyue MAO, Wei XIE, Yutong YANG, Jinlong GUO, Yangbo LI, Zhengkang REN, Zhipeng CHEN, Nengchao WANG, the J-TEXT Team. Characteristics of the SOL ion-to-electron temperature ratio on the J-TEXT tokamak with different plasma configurations[J]. Plasma Science and Technology, 2024, 26(2): 025101. DOI: 10.1088/2058-6272/ad0c1e

Characteristics of the SOL ion-to-electron temperature ratio on the J-TEXT tokamak with different plasma configurations

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  • Author Bio:

    Yunfeng LIANG: y.liang@fz-juelich.de

  • Corresponding author:

    Yunfeng LIANG, y.liang@fz-juelich.de

  • Received Date: May 11, 2023
  • Revised Date: July 25, 2023
  • Accepted Date: July 31, 2023
  • Available Online: January 15, 2024
  • Published Date: February 06, 2024
  • Accurate measurement of the average plasma parameters in the edge region, including the temperature and density of electrons and ions, is critical for understanding the characteristics of the scrape-off layer (SOL) and divertor plasma transport in magnetically confined fusion research. On the J-TEXT tokamak, a multi-channel retarding field analyzer (RFA) probe has been developed to study average plasma parameters in the edge region under various poloidal divertor and island divertor configurations. The edge radial profile of the ion-to-electron temperature ratio, τi/e, has been determined, which gradually decreases as the SOL ion self-collisionality, νSOL, increases. This is broadly consistent with what has been observed previously from various tokamak experiments. However, the comparison of experimental results under different configurations shows that in the poloidal divertor configuration, even under the same νSOL, τi/e in the SOL region becomes smaller as the distance from the X-point to the target plate increases. In the island divertor configuration, τi/e near the O-point is higher than that near the X-point at the same νSOL, and both are higher than those in the limiter configuration. These results suggest that the magnetic configuration plays a critical role in the energy distributions between electrons and ions at the plasma boundary.

  • Silicone rubber (SIR) is widely used in electrical engineering due to its excellent mechanical strength and insulation properties [1]. Generally, combination insulation systems are inevitably formed in high-voltage power systems when the solid insulating materials contact the vacuum or air. The weakest link of insulation systems mainly depends on the interfaces, along which the flashover strength is usually much lower than the bulk electrical breakdown strength [2]. Therefore, improving the surface insulating strength of electrical materials has become a hot issue in the high-voltage engineering field. In recent years, direct fluorination has been proved to be an effective method for improving the surface flashover withstanding strength. Liu et al treated the low-density polyethylene samples in the mixed gas of F2 and N2 and found that the micro-size fluorinated layer was formed on the surface, the increased roughness and conductivity are helpful for the improvement of surface flashover in vacuum [3]. Wang et al applied the same method on the epoxy resin (ER) filled with different ratios of Al2O3 grain. It was observed that the surface charge dissipation is accelerated after direct fluorination treatment [4]. Zhou et al further investigated the surface electron trap and secondary electron emission characteristics of ER and polyethylene (PE) after direct fluorination. It is concluded that the reduction of surface secondary electron yield has a direct link with the improvement of flashover voltage. Besides, they also built a comprehensive flashover suppression model based on direct fluorination [5]. Although the method of direct fluorination is effective, the usage of F2, as a kind of toxic gas with high activity, has a potential threat to the humans and environment.

    In recent years, plasma surface modification has attracted wide attention because of its high efficiency and environmental friendliness [68]. Chen et al utilized the He/CF4 atmospheric pressure plasma jet for the surface treatment of ER samples and considered that the enhancement of flashover strength is the result of physical and chemical effects [9, 10]. Based on this result, they also found that the proper addition of CO2 can decrease the fluorine-to-carbon ratio (F/C) in plasma, which is helpful for the formation of fluorinated layers [11]. The surface conductivity of treated samples by He/CO2/CF4 atmospheric pressure plasma decreases by two orders of magnitude and the surface charge accumulation is inhibited obviously, which contributes to the improvement of flashover voltage. Shao et al also reported that dielectric barrier discharge using Ar/CF4 mixed gas at atmospheric pressure can increase the surface roughness and introduce the fluorocarbon group, which can reduce the surface secondary electron emission coefficient and improve the flashover voltage of PMMA [12].

    Radio frequency capacitively coupled plasma (CCP) can produce active species with high energy uniformly in a large area [13]. Driven by the industrial radio frequency power with mature technology, it also has an economic advantage. Therefore, it is usually applied in surface modification and microelectronic processing [1416]. The previous study has demonstrated that RF discharge in CF4 gas can improve the hydrophobicity of SIR [17], but the studies about the improvement of surface flashover withstanding strength are hardly found. Therefore, in this work, we explore the discharge characteristic of CF4 CCP and utilize it for modifying the surface of SIR. Besides, the physicochemical changes, and charge accumulation and dissipation behavior on SIR samples surface for different treatment time are investigated. Combined with the surface flashover test, the mechanism of improving the surface withstanding strength by CF4 CCP is studied.

    Silicon rubber samples (Shandong Anlan Power Technology Co., China) are composed of the polydimethylsiloxane (PDMS) matrix and inorganic filler (Al(OH)3 and SiO2), which are cut into 50 mm×50 mm×1 mm slices. They are washed in an ultrasonic cleaner by deionized water before plasma treatment for 30 min, soaked in absolute alcohol for 10 min, then dried in a vacuum drying oven at 60 ℃ for 12 h.

    The plasma surface treatment setup is shown in figure 1. The CCP reactor consists of symmetrical stainless-steel electrodes with a diameter of 14 cm and a gap of 2 cm. A 13.56 MHz RF power supply (VERG-300, Zhongshan K-mate Electronics Co., Ltd) is used to generate low-temperature plasma and the SIR samples are placed on the grounded electrode. To remove the impact of impurity gas, the cavity is washed with high-pure CF4 (99.99%) three times before processing the material. Controlling the mass flowmeter and mechanical pump, the working gas can be maintained at different pressures. Moreover, the discharge voltage and current are measured by a high voltage probe (Tektronix P6015A) and a current probe (Pearson 2877) respectively, and recorded by a digital oscilloscope (WaveSurfer 104MXs-B, LeCroy). For further analysis of CCP discharge mode and discharge products, CCP discharge images are captured by a digital single-lens reflex (Canon 60D) and the emission spectra is probed by a triple grating spectrometer (Andor SR-303I-A).

    Figure  1.  CCP treatment setup.

    The surface morphology of SIR samples is observed by scanning electron microscope (SEM, MAIA3 LMH, TESCAN). The surface chemical composition is analyzed by x-ray photoelectron spectroscopy (XPS, Thermo Fisher ESCALAB Xi+), and the XPS data is fitted by Thermo Fisher Scientific Avantage 5.979.

    The surface potential and surface flashover are measured in a stainless-steel vacuum chamber, as can be seen in figure 2. The chamber is equipped with a mechanical pump and a molecular pump, which can form the cascade structure and maintain the air pressure below 10-3 Pa. The high-voltage electrode is applied with negative standard lightning impulse voltage (1.2/48 μs) generated by a Marx generator and the grounded electrode is connected with the chamber, while the electrode distance is fixed to 10 and 5 min for the surface potential measurement and flashover voltage test respectively. Moved by the displacement platform, surface potential on samples is detected by a Kelvin probe and displays on an electrostatic voltmeter. The distance between the probe and the sample surface is 2 mm, and the measurement range is 48 mm×30 mm. Surface flashover voltage is characterized by three parameters, the first breakdown voltage (Ufb), conditioned voltage (Uco) and hold-off voltage (Uho). Firstly, the samples are continuously applied with a low voltage (-10 kV) five times. If the flashover does not happen, the voltage will increase by 1 kV each time until the flashover happened, which is called the first breakdown voltage (Ufb). Then the voltage is increased until the flashover happened five times in five tests, which is called the conditioned voltage (Uco). Finally, the voltage will decrease gradually until the flashover does not happen, which is called hold-off voltage (Uho).

    Figure  2.  Surface charge accumulation and surface flashover voltage measurement setup.

    Isothermal surface potential decay (ISPD) measurement is carried out in the thermal tank set at 50 ℃ in figure 3. Negative corona discharge can be generated from the needle tip electrode, which is applied with the negative polarity voltage (-15 kV). Under the relatively uniform electric field between the metal mesh electrode and grounded electrode, the charged particles could be deposited on the sample evenly. The charging time is 15 min and the samples are moved under the electrostatic probe after turning on the electrostatic voltmeter.

    Figure  3.  ISPD measurement setup.

    Figure 4(a) shows the discharge images when the output power is set as 150 W and the gas pressure is 100 Pa, 200 Pa, and 300 Pa respectively. When the gas pressure is 100 Pa, the diffuse discharge can be observed in the whole electrode space. According to previous researches on CCP characteristics, the discharge state is maintained at the DA model. Under this condition, a large amount of electrons multiplies repeatedly in the electric field of the sheath and drifts rapidly in the plasma. Increasing the gas pressure to 200 Pa, the discharge began to transform to γ mode gradually. Due to the contraction of plasma sheaths, positive ions will bombard the electrode and generate secondary electrons, which will accelerate the electron impact near the plasma sheath. Therefore, the obvious negative glow region and Faraday dark region can be observed near electrodes. Subsequently, when the gas pressure is further increased to 300 Pa, the negative glow region gradually shrinks and a distinct positive column region appears in the center of the electrode because of the impact of high energy electrons in the plasma region. The discharge waveform at 200 Pa and 150 W can be seen from figure 4(b), the peak voltage and current are 204 V and 1.5 A respectively and the phase shift between voltage and current is 67.3°. Because of its stable discharge and intense bombardment effect, this discharge condition is selected for plasma surface treatment.

    Figure  4.  Discharge properties of CCP. (a) Discharge image of CCP at 100 Pa, 200 Pa and 300 Pa; (b) discharge waveforms of CCP at 200 Pa.

    The optical emission spectra of CCP are presented in figure 5. Necessarily, the wavelength of the spectrometer is calibrated by the standard line spectrum of a mercury argon lamp. The continuous spectra ranging from 220 to 380 nm are responsible for CF2+ and CF3+ in the UV region and other continuous spectra ranging from 400 to 700 nm are related to CF3 [18]. Besides, most of the sharp line spectra observed between 650 and 800 nm are from F atoms [19].

    Figure  5.  Emission spectra of CCP at 200 Pa.

    According to the results of spectroscopic diagnosis, the main reaction equations involved in CF4 CCP are as follows [20]:

    CF4+eCF3+F+e, (1)
    CF+4eCF+2+2F+e, (2)
    CF4+eCF3+F-, (3)
    CF3+eCF+3+2e, (4)
    CF3+eCF+2+F+2e. (5)

    The surface morphology of SIR samples treated at different time is demonstrated in figure 6, the surface of virgin samples is relatively smooth without obvious particles and defects in figure 6(a), but the sample surface treated for 5 min has obvious wrinkles and cracks and the texture becomes rough in figure 6(b). When the treatment time comes to 10 min, a large number of micron and sub-micron particles appear on the surface of samples, which is shown in figure 6(c). Furthermore, particle diameter increases with longer treatment time and some small holes can also be observed. Increasing the treatment time to 20 min, dense and uniform micron-sized particles can be found on the surface of samples in figure 6(e), while obvious particle agglomeration can be found. The surface morphology changes can be attributed to plasma bombardment and chemical grafting. Specifically, the chemical interaction and collisions between ion particles and electrons induce ion scattering, the bombardment and strain in different directions will lead to the roughness of wrinkles on samples [21]. Besides, the bombardment effect is also helpful for the side-chain cleavage (Si–C bond and C–H bond in Si–CH3), and even breaks the main-chain structure (Si–O bond in [–Si–O–Si–]n). Therefore, the fluorocarbon groups in plasma are more inclined to graft on the sample surface, gradually form the agglomeration of fluorocarbon particles, and more inorganic filler (SiO2/Al(OH)3) existing in the PDMS matrix will be exposed due to the destruction of surface structure. The chemical structure changes will be discussed in the following part.

    Figure  6.  SEM image of SIR surface at different treatment time (×5000). (a) 0 min, (b) 5 min, (c) 10 min, (d) 15 min, (e) 20 min and (f) the image of cross-section layers.

    The surface chemical composition changes on SIR samples treated at different time are shown in table 1. The untreated samples are composed of C, O, and Si, which are roughly consistent with the PDMS matrix and slightly affected by inorganic filler. After 5 min CCP treatment, the content of the F element increases rapidly, while those of the C, O, and Si decrease. This result is attributed to the surface chemical grafting of fluorocarbon groups from CCP plasma. In addition, combining the SEM images displayed above, it can be inferred that the side-chain cleavage caused by plasma bombardment will enhance the grafting process. With further treatment time (10–20 min), small amounts of Al element can be observed and the contents of C and F come to decrease while those of Si, O, and Al increase gradually. This result can come from two aspects. On one hand, the sustained plasma bombardment leads to the ablation of PDMS and accelerates the filler exposure, which introduces many Si, O, and Al elements. On the other hand, the bombardment effect of plasma may cause stripping of the fluorocarbon group grafted on the surface.

    Table  1.  The chemical composition of SIR.
    Chemical composition (%)
    Treatment time (min) C O F Si Al
    0 52.55 25.66 0 21.79 0
    5 37.77 4.93 53.01 4.29 0
    10 35.68 11.13 42.51 8.54 2.14
    15 30.58 19.91 32.01 13.4 4.09
    20 29.50 24.00 21.56 16.23 8.70
     | Show Table
    DownLoad: CSV

    In order to further investigate the chemical state of C1s and F1s. The peak-fitting of C1s peak and the relative contents of the C–F and Si–F bond are shown in figure 7. The related bonds for C element mainly include C–H, C–O/C–CF2, C=O, CF–CF2, CF2 and CF3, and their binding energy is at 284.3 eV, 286.6 eV, 288.3 eV, 289.3 eV, 291.0 eV and 293.0 eV respectively [22, 23]. Simply, the F element only exists in C–F and Si–F. The functional groups on untreated samples mainly include C–H and small amounts of C–O, C=O, the latter may come from impurities pollution. Treated by 5 min, the content of C–CF2/CF–CF2/CF2/CF3 dramatically increases and the C–H group decreases in figure 7(b). Notably, the content of C–F is far more than that of Si–F. It can be described that CF3 and CF2, as the primary product of CCP, certainly have more chance to graft on the surface, and form the new structure as [–SiFx (CH3)2-x –O–] n or [–SiF x (CF y H3-y)2-x –O–] n (x≤2, y≤3). However, with a longer treatment time, the content of the fluorocarbon group decreases gradually, which demonstrates that the chemical grafting has been inhibited due to the appearance of more inorganic filler. Besides, the Si–CFn structure is also easily subject to the destruction of plasma bombardment and forms a more stable structure of Si–F, owing to stronger bond dissociation energy in Si–F. Therefore, the Si–F bond has excessed 30% in F elements after 20 min treatment, as illustrated in figure 7(f).

    Figure  7.  Peak-fitting for C1s of SIR at different treatment time. (a) 0 min, (b) 5 min, (c) 10 min, (d) 15 min, (e) 20 min, and (f) is the relative content of C–F and Si–F bond.

    The surface potential decay curve of samples treated at different treatment time is shown in figure 8(a). The initial potential is -6 kV, and the surface decay time to 80% of the initial potential needs 736 s, 944 s, 1749 s, 3064 s, and 8765 s respectively. The results demonstrate that the surface charge dissipation can be inhibited after CCP treatment and the increased inhibition effect can be found with the extension of processing time. The decaying rate of the surface potential on samples treated for 20 min is less than 10% of that of the untreated samples.

    Figure  8.  Surface potential decay curve and trap distribution.

    According to the isothermal surface potential decay model (ISPD) [24], the electron trap distribution on the SIR samples can be calculated simply, it is assumed that the trap distribution is uniform and the de-trapped charge cannot be captured again. The calculation equation of electron trap energy level and electron trap density is as follows:

    Et=kTln(γt), (6)
    N(Et)=ε0εrtkTf0(Et)δLqdVsdt. (7)

    where k is the Boltzmann constant, T is the absolute temperature, γ is the escape frequency of a trapped electron, set as 4.17×1013 s-1, ε0 is the permittivity of the vacuum, εr is the relative permittivity of the dielectric, q is Coulomb's quantity of electron, δ is the thickness of the top charge layer, usually set as 2 mm, L is the thickness of the sample, and the rate of initial occupancy of traps is f0(Et), which is determined by the injection of electrons.

    The surface electron trap distribution of SIR samples treated at different time is shown in figure 8(b). For the virgin samples, the central electron trap energy level is 0.913 eV and the corresponding trap density is 3.38×1021 eV-1·m-3. In contrast, the surface central trap energy level and trap density will increase obviously for the treated sample. The central electron trap energy level is at 0.926 and 0.948 eV for the samples treated for 5 and 10 min and their trap density is about 3.5×1021 eV-1·m-3. When the treatment time is increased to 20 min, the central trap energy level is more than 1.0 eV and the corresponding trap density can reach 3.5×1021 eV-1·m-3.

    Previous researchers have demonstrated that the surface electron traps inside polymer are mainly formed by physical defects and chemical defects [25]. On one hand, the CCP treatment will make the surface rougher and some electrons can be blocked due to the physical barriers. On the other hand, the grafting of fluorocarbon functional groups has formed many C–F structures with negative electron affinity, which will attract the electron. Therefore, the physicochemical changes on the sample surface increase the electron trap energy level and density.

    The surface potential distribution of SIR samples for different treatment time is shown in figure 9. The impulse voltage at -17 kV is applied 20 times on the SIR samples consecutively. It is clearly found that the positive potential has appeared on the regions of the sample surface, which indicates the accumulation of positive charge. For the untreated samples in figure 9(a), high potential can be observed on the whole sample and the maximum potential is 4.8 kV near the cathode. When the treatment time increases, as shown in figures 9(c)(e), the surface potential begins to reduce and the high potential region is contracted to the cathode area. Especially, the surface potential has decreased to the most extent and the maximum potential is only 3.1 kV after 20 min plasma treatment.

    Figure  9.  Surface potential distribution under different treatment time. (a) 0 min, (b) 5 min, (c) 10 min, (d) 15 min, (e) 20 min. The applied voltage is -17 kV and the pulse number N=20.

    The different number of pulses at the voltage of -14 kV is applied on the samples untreated and treated for 20 min and the surface potential distribution is shown in figure 10. The maximum voltage is 3.9 kV after 10 pulses on the virgin sample surface and it has little change after 20 pulses. However, the surface potential has a rapid rise when the pulse number is increased to 30, distinctly, the maximum potential can reach 5 kV and the surface charge shows an obvious diffusion trend. After plasma treatment for 20 min, the charge accumulation on the surface of treated samples has decreased obviously. The maximum surface potential is 2.3 kV after 10 pulses. With the increase of pulse number, the maximum surface potential hardly changes.

    Figure  10.  Surface potential distribution under different pulse number N. (a) N=10, (b) N=20, (c) N=30 for the virgin samples. (d) N=10, (e) N=20, (f) N=30 for the samples treated by 20 min. The applied voltage is -14 kV.

    The result of vacuum surface flashover of SIR samples is shown in figure 11. The Ufb, Uco, and Uho are 19.71 kV, 24.05 kV, and 16.96 kV respectively for the origin samples. Comparatively, the Ufb, Uco, and Uho of treated samples all have been improved significantly. When the treatment time is 10 min, Ufb and Uco have increased by 21.2% and 26.67% and reach their maximum of 23.88 and 30.4 kV. With the increase of treatment time, Ufb and Uco come to decrease, which may be attributed to the excessive treatment. However, the Uho has some differences from Ufb and Uco. Although it has a considerable raise compared to the original value, this voltage does not show a stable trend. This result may be attributed to the insulation damage after multiple flashovers happed on the surface.

    Figure  11.  Flashover voltage of SIR samples under different treatment time.

    The surface charge accumulation and flashover voltage of SIR samples have been evidently improved by CCP treatment. The results show that plasma treatment has multiple effects on the physical morphology and chemical composition of samples surface.

    The cooperating effect and competitive relation both exist between chemical grafting and physical bombardment during the process of CCP treatment on the SIR samples. When the treatment time is shorter than 10 min, the cooperative effect is obvious. Specifically, the plasma bombards the superficial layer and causes the cleavage of side chains of PDMS, which is more conducive for the chemical grafting of fluorocarbon groups. However, with the increase of treatment time, the competitive relation appears gradually, the long-time plasma bombardment can make the stripping of fluorocarbon group grafted on samples. Furthermore, the exposure of fillers can also impede the grafting reaction. Therefore, the surface roughness of SIR samples increases obviously and the relative content of F elements decreases with the increase of plasma treatment time.

    Previous studies show that increased roughness and the introduction of C–F bonds can improve the surface flashover voltage [26, 27]. According to the theory about vacuum flashover, surface flashover starts with primary electrons emitted from the cathode triple junction (CTJ) and is accelerated by the applied external field. The secondary electron emission will be induced by the collision of primary electrons on dielectric and gradually forms the secondary electronic emission avalanche (SEEA) towards the anode. This course will leave positive charges and unleash desorbed gas molecules on the sample surface. When the surface field strength is high enough, gas ionization finally results in the breakdown across the vacuum-insulator interface. Therefore, in this work, the improvement of surface flashover can be considered from two aspects. On one hand, as shown in figure 8(b), the physicochemical changes on samples surface treated by CCP, the grafting of fluorocarbon group, and the increased roughness will increase the electron trap energy level and density. When primary electrons are emitted from CTJ, they can be captured by the fluorocarbon group with strong electron affinity and blocked by the surface barrier, which will inhibit the development of SEEA.

    On the other hand, the polarity and distribution of surface charges will change the surface electric field, then alter the trajectory of electrons, and finally affect the surface flashover voltage [28]. The accumulation of positive charges near the cathode will strengthen the local electric field, especially the normal electric field, which will introduce secondary electron avalanche and decrease flashover voltage. From figures 9 and 10, the maximum surface potential on the treated samples has decreased by 35.42% compared with the virgin samples and there is no obvious accumulation effect after multiple pulses. Therefore, the decrease of the positive charges will increase the surface flashover voltage.

    CF4 CCP is utilized to improve the surface flashover withstanding strength of SIR. The discharge of CCP is maintained at γ model, where the plasma contains amounts of active particles, as CF3+, CF2+, CF3 and F, and has a bombardment effect for the sample surface. The physicochemical changes and the electrical property on the sample surface are investigated and some main conclusion is as follows:

    1. The chemical grafting and physical bombardment has increased the content of F on the surface and improved the surface roughness. The short-time bombardment is conducive to the grafting of fluorocarbon groups, but long-time treatment would lead to the striping of fluorocarbon groups.

    2. The surface potential decay has been inhibited and the electron trap energy level is increased, which will suppress the emission of primary electrons and the development of SEEA.

    3. The surface flashover on SIR samples is not only related to the second electron emission avalanche but affected by the surface charge accumulation. Suppressing the accumulation of positive charge near the cathode will improve the surface flashover voltage.

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    [3]Yuqing YANG (杨宇晴), Xinjun ZHANG (张新军), Yanping ZHAO (赵燕平), Chengming QIN (秦成明), Yan CHENG (程艳), Yuzhou MAO (毛玉周), Hua YANG (杨桦), Jianhua WANG (王健华), Shuai YUAN (袁帅), Lei WANG (王磊), Songqing JU (琚松青), Gen CHEN (陈根), Xu DENG, (邓旭), Kai ZHANG (张开), Baonian WAN (万宝年), Jiangang LI (李建刚), Yuntao SONG (宋云涛), Xianzu GONG (龚先祖), Jinping QIAN (钱金平), Tao ZHANG (张涛). Recent ICRF coupling experiments on EAST[J]. Plasma Science and Technology, 2018, 20(4): 45102-045102. DOI: 10.1088/2058-6272/aaa599
    [4]Guozhong DENG (邓国忠), Liang WANG (王亮), Xiaoju LIU (刘晓菊), Yanmin DUAN (段艳敏), Jiansheng HU (胡建生), Changzheng LI (李长征), Ling ZHANG (张凌), Shaocheng LIU (刘少承), Huiqian WANG (汪惠乾), Liang CHEN (陈良), Jichan XU (许吉禅), Wei FENG (冯威), Jianbin LIU (刘建斌), Huan LIU (刘欢), Guosheng XU (徐国盛), Houyang GUO (郭后扬), Xiang GAO (高翔), the EAST team. Achieving temporary divertor plasma detachment with MARFE events by pellet injection in the EAST superconducting tokamak[J]. Plasma Science and Technology, 2017, 19(1): 15101-015101. DOI: 10.1088/1009-0630/19/1/015101
    [5]CHEN Gen (陈根), QIN Chengming (秦成明), MAO Yuzhou (毛玉周), ZHAO Yanping (赵燕平), YUAN Shuai (袁帅), ZHANG Xinjun (张新军). Power Compensation for ICRF Heating in EAST[J]. Plasma Science and Technology, 2016, 18(8): 870-874. DOI: 10.1088/1009-0630/18/8/14
    [6]LU Xiaofei (陆小飞), FU Peng (傅鹏), ZHUANG Ming (庄明), QIU Lilong (邱立龙), HU Liangbing (胡良兵). Process Modeling and Dynamic Simulation for EAST Helium Refrigerator[J]. Plasma Science and Technology, 2016, 18(6): 693-698. DOI: 10.1088/1009-0630/18/6/18
    [7]LI Changzheng(李长征), HU Jiansheng(胡建生), CHEN Yue(陈跃), LIANG Yunfeng(梁云峰), LI Jiangang(李建刚), LI Jiahong(李加宏), WU Jinhua(吴金华), HAN Xiang(韩翔). First Results of Pellet Injection Experiments on EAST[J]. Plasma Science and Technology, 2014, 16(10): 913-918. DOI: 10.1088/1009-0630/16/10/03
    [8]WANG Fuqiong(王福琼), CHEN Yiping(陈一平), HU Liqun(胡立群). DIVIMP Modeling of Impurity Transport in EAST[J]. Plasma Science and Technology, 2014, 16(7): 642-649. DOI: 10.1088/1009-0630/16/7/03
    [9]ZHANG Shoubiao(张寿彪), GAO Xiang(高翔), LING Bili(凌必利), WANG Yumin(王嵎民), ZHANG Tao(张涛), HAN Xiang(韩翔), LIU Zixi(刘子奚), BU Jingliang(布景亮), LI Jiangang(李建刚), EAST team. Density Profile and Fluctuation Measurements by Microwave Reflectometry on EAST[J]. Plasma Science and Technology, 2014, 16(4): 311-315. DOI: 10.1088/1009-0630/16/4/02
    [10]YANG Yao, GAO Xiang, the EAST team. Energy Confinement of both Ohmic and LHW Plasma on EAST[J]. Plasma Science and Technology, 2011, 13(3): 312-315.

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