In this paper, poly (acrylamide-co-acrylic acid) (P(AM-co-AA)) hydrogel was pre- pared in an aqueous solution by using glow-discharge electrolysis plasma (GDEP) induced copoly- merization of acrylamide (AM) ...In this paper, poly (acrylamide-co-acrylic acid) (P(AM-co-AA)) hydrogel was pre- pared in an aqueous solution by using glow-discharge electrolysis plasma (GDEP) induced copoly- merization of acrylamide (AM) and acrylic acid (AA), in which N,N'-methylenebisacrylamide (MBA) was used as a crosslinker. A mechanism for the synthesis of P(AM-co-AA) hydrogel was proposed. To optimize the synthesis condition, the following parameters were examined in detail: the discharge voltage, discharge time, the content of the crosslinker, and the mass ratio of AM to AA. The results showed that the optimum pH range for cationic dyes removal was found to be 5.0-10.0. The P(AM-co-AA) hydrogel exhibits a very high adsorption potential and the ex- perimental adsorption capacities for Crystal violet (CV) and Methylene blue (MB) were 2974.3 mg/g and 2303.6 mg/g, respectively. The adsorption process follows a pseudo-second-order kinetic model. In addition, the adsorption mechanism of P(AM-co-AA) hydrogel for cationic dyes was also discussed.展开更多
The effect of a negative DC bias,|V_(dc)|,on the electrical parameters and discharge mode is investigated experimentally in a radiofrequency(RF)capacitively coupled Ar plasma operated at different RF voltage amplitude...The effect of a negative DC bias,|V_(dc)|,on the electrical parameters and discharge mode is investigated experimentally in a radiofrequency(RF)capacitively coupled Ar plasma operated at different RF voltage amplitudes and gas pressures.The electron density is measured using a hairpin probe and the spatio-temporal distribution of the electron-impact excitation rate is determined by phase-resolved optical emission spectroscopy.The electrical parameters are obtained based on the waveforms of the electrode voltage and plasma current measured by a voltage probe and a current probe.It was found that at a low|V_(dc)|,i.e.inα-mode,the electron density and RF current decline with increasing|V_(dc)|;meanwhile,the plasma impedance becomes more capacitive due to a widened sheath.Therefore,RF power deposition is suppressed.When|V_(dc)|exceeds a certain value,the plasma changes toα–γhybrid mode(or the discharge becomes dominated by theγ-mode),manifesting a drastically growing electron density and a moderately increasing RF current.Meanwhile,the plasma impedance becomes more resistive,so RF power deposition is enhanced with|V_(dc)|.We also found that the electrical parameters show similar dependence on|V_(dc)|at different RF voltages,andα–γmode transition occurs at a lower|V_(dc)|at a higher RF voltage.By increasing the pressure,plasma impedance becomes more resistive,so RF power deposition and electron density are enhanced.In particular,theα–γmode transition tends to occur at a lower|V_(dc)|with increase in pressure.展开更多
The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results s...The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results show that plasma exists inside the cavity when the sheath inside the hollow electrode hole is fully collapsed, which is an essential condition for the plasma density enhancement outside hollow electrodes. In addition, the existence of the electron density peak at the orifice is generated via the hollow cathode effect(HCE), which plays an important role in the density enhancement. It is also found that the radial width of bulk plasma at the orifice affects the magnitude of the density enhancement, and narrow radial plasma bulk width at the orifice is not beneficial to obtain high-density plasma outside hollow electrodes.Higher electron density at the orifice, combined with larger radial plasma bulk width at the orifice,causes higher electron density outside hollow electrodes. The results also imply that the HCE strength inside the cavity cannot be determined by the magnitude of the electron density outside hollow electrodes.展开更多
Improvement of the bonding strength and durability between the dentin surface and the composite resin is a challenging job in dentistry. In this paper, a radio-frequency atmosphericpressure glow discharge(RF-APGD) pla...Improvement of the bonding strength and durability between the dentin surface and the composite resin is a challenging job in dentistry. In this paper, a radio-frequency atmosphericpressure glow discharge(RF-APGD) plasma jet is employed for the treatment of the acid-etched dentin surfaces used for the composite restoration. The properties of the plasma treated dentin surfaces and the resin–dentin interfaces are analyzed using the x-ray photoemission spectroscopy, contact angle goniometer, scanning electron microscope and microtensile tester.The experimental results show that, due to the abundant chemically reactive species existing in the RF-APGD plasma jet under a stable and low energy input operating mode, the contact angle of the plasma-treated dentin surfaces decreases to a stable level with the increase of the atomic percentage of oxygen in the specimens; the formation of the long resin tags in the scattered clusters and the hybrid layers at the resin–dentin interfaces significantly improve the bonding strength and durability. These results indicate that the RF-APGD plasma jet is an effective tool for modifying the chemical properties of the dentin surfaces, and for improving the immediate bonding strength and the durability of the resin-dentin bonding in dentistry.展开更多
Spherical powders with good flowability and high stacking density are mandatory for powder bed additive manufacturing. Nevertheless, the preparation of spherical refractory tungsten and tungsten alloy powders is a for...Spherical powders with good flowability and high stacking density are mandatory for powder bed additive manufacturing. Nevertheless, the preparation of spherical refractory tungsten and tungsten alloy powders is a formidable task. In this paper, spherical refractory metal powders processed by high-energy stir ball milling and RF inductively coupled plasma were investigated. By utilizing the technical route, pure spherical tungsten powders were prepared successfully, the flowability increased from 10.7 s/50 g to 5.5 s/50 g and apparent density increased from 6.916 g cm-3 to 11.041 g cm-3. Alloying element tantalum can reduce the tendency to micro- crack during tungsten laser melting and rapid solidification process. Spherical W-6Ta (%wt) powders were prepared in this way, homogeneous dispersion of tantalum in a tungsten matrix occurred but a small amount of flake-like shape particles appeared after high-energy stir ball milling. The flake-like shape particles can hardly be spheroidized in subsequent RF inductively coupled plasma process, might result from the unique suspended state of flaky particles under complex electric and magnetic fields as well as plasma-particle heat exchange was different under various turbulence models. As a result, the flake-like shape particles cannot pass through the high-temperature area of thermal plasma torch and cannot be spheroidized properly.展开更多
This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc d...This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc discharge sources. Due to the absence of hotfilaments they exhibit an inherent simplicity both in mechanical and electrical aspects andconsequently offer advantages in terms of cost savings, gain in availability and reliability andreduced maintenance. This renders the RF plasma source attractive for any long pulse (> 10 sec) NBIsystem and in particular for the ITER NBI system. The latter, however, requires that the RF plasmasource is also capable of delivering negative rather than positive hydrogen ions. In the first partof the paper the types, characteristics and operation experience of RF plasma sources for positiveions in operation are described. The second part is devoted to the development for ITER NBI: thebasic requirements, physics and technology issues and the present status are discussed.展开更多
The electric and plasma characteristics of RF discharge plasma actuation under varying pressure have been inves- tigated experimentally. As the pressure increases, the shapes of charge-voltage Lissajous curves vary, a...The electric and plasma characteristics of RF discharge plasma actuation under varying pressure have been inves- tigated experimentally. As the pressure increases, the shapes of charge-voltage Lissajous curves vary, and the discharge energy increases. The emission spectra show significant difference as the pressure varies. When the pressure is 1000 Pa, the electron temperature is estimated to be 4.139 eV, the electron density and the vibrational temperature of plasma are /peak /lPeak which describes the electron temper- 4.71 x 10^11 cm-3 and 1.27 eV, respectively. The ratio of spectral lines "391.4/'380.5 ature hardly changes when the pressure varies between 5000-30000 Pa, while it increases remarkably with the pressure below 5000 Pa, indicating a transition from filamentary discharge to glow discharge. The characteristics of emission spec- trum are obviously influenced by the loading power. With more loading power, both of the illumination and emission spectrum intensity increase at 10000 Pa. The pin-pin electrode RF discharge is arc-like at power higher than 33 W, which results in a macroscopic air temperature increase.展开更多
We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasm...We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions (IEDs) and ion angle distributions (IADs) on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.展开更多
Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectra...Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectral lines are detected by increasing the input power (0-6 kW) of ICPs (inductively coupled plasmas). With the increase of net input power, the intensity of Hα im- proves rapidly (0-2 kW), and then reaches its dynamic equilibrium; the intensities of Hβ can be divided into three processes: obvious increase (0-2 kW), rapid increase (2-4 kW), almost constant (4-6 kW); while the intensities of Hγ increase very slowly. The energy levels of the excited hydro- gen atoms and the splitting energy levels produced by an obvious Stark effect play an important role in the results.展开更多
In previous studies on plasma-particle interaction, as far as we know, the rf plasma flow and temperature fields are all simulated by the non-self-consistent one-dimensional electromagnetic (1-D EM) field model. In th...In previous studies on plasma-particle interaction, as far as we know, the rf plasma flow and temperature fields are all simulated by the non-self-consistent one-dimensional electromagnetic (1-D EM) field model. In the present paper, the complete self-consistent two-dimensional electromagnetic (2-D EM) field model in- corporating the axial Lorentz force component, which is neglected in the 1-D model, is firstly adopted to calculate the aluminium particle trajectory and thermal history in atmospheric rf Ar plasma with the particle evaporation effect included. The cru- cial effect of reverse flow within the coil region on the particle trajectory is discovered and the results show that the 2-D EM field model must be adopted instead of the 1-D model when the plasma-particle interaction is studied. The effect of carrier gas flux on the particle movement and heating are also studied, resulting in some useful conclusions for both plasma theory and application.展开更多
The tokamak plasma flows induced by the local radio frequency (RF) forces in the core region are analyzed. The effective components of local RF forces are composed of the momentum absorption term and the resonant pa...The tokamak plasma flows induced by the local radio frequency (RF) forces in the core region are analyzed. The effective components of local RF forces are composed of the momentum absorption term and the resonant parallel momentum transport term (i.e. the parallel component of the resonant ponderomotive forces). Different momentum balance relations are em- ployed to calculate the plasma flows depending on different assumptions of momentum transport. With the RF fields solved from RF simulation codes, the toroidal and poloidal flows by these forces under the lower hybrid current drive and the mode conversion ion cyclotron resonance heating on EAST-like plasmas are evaluated.展开更多
Measurement of the oxygen dissociation fraction in RF low pressure oxygen/argon plasma using optical emission spectrometry is presented. The oxygen dissociation fraction and its evolutions as functions of operational ...Measurement of the oxygen dissociation fraction in RF low pressure oxygen/argon plasma using optical emission spectrometry is presented. The oxygen dissociation fraction and its evolutions as functions of operational parameters were determined using argon as the actinometer. At a pressure of 30 Pa, the oxygen dissociation fraction decreased from 13.4% to 9.5% as the input power increased from 10 W to 70 W. At an input power of 50 W, the oxygen dissociation fraction decreased from 12.3% to 7.7% when the gas pressure increased from 10 Pa to 40 Pa. The influences of operational parameters on the generation of atomic oxygen were also discussed.展开更多
In this study,numerical simulation and discharge current tests were conducted on an inductively coupled radio frequency(RF)plasma cathode.Numerical simulations and experimental measurements were performed to study the...In this study,numerical simulation and discharge current tests were conducted on an inductively coupled radio frequency(RF)plasma cathode.Numerical simulations and experimental measurements were performed to study the factors influencing the electron extraction characteristics,including the gas type,gas flow,input power and extracting voltage.The simulation results were approximately consistent with the experimental results.We experimentally found that the RF input power mainly determines the extracted electron current.An electron current greater than 1 A was acquired at 270 W(RF input power),2.766 sccm(xenon gas).Our results prove that an inductively coupled RF plasma cathode can be reasonable and feasible,particularly for low power electric propulsion devices.展开更多
The RF electric field penetration and the power deposition into planar-type inductively coupled plasmas in low-pressure discharges have been studied by means of a self-consistent model which consists of Maxwell equati...The RF electric field penetration and the power deposition into planar-type inductively coupled plasmas in low-pressure discharges have been studied by means of a self-consistent model which consists of Maxwell equations combined with the kinetic equation of electrons. The Maxwell equations are solved based on the expansion of the Fourier-Bessel series for determining the RF electric field. Numerical results show the influence of a non-Maxwellian electron energy distribution on the RF electric field penetration and the power deposition for different coil currents. Moreover, the two-dimensional spatial profiles of RF electric field and power density are also shown for different numbers of RF coil turns.展开更多
A radio frequency(RF)driven ion source is a very important component of a neutral beam injector for large magnetic confinement fusion devices.In order to study the key technology and physics of an RF driven ion source...A radio frequency(RF)driven ion source is a very important component of a neutral beam injector for large magnetic confinement fusion devices.In order to study the key technology and physics of an RF driven ion source for a neutral beam injector in China,an RF ion source test facility was developed at the Institute of Plasma Physics,Chinese Academy of Sciences.In this paper,a two-dimensional fluid model is used to simulate the fundamental physical characteristics of RF plasma discharge.Simulation results show the relationship of the characteristics of plasma(such as electron density and electron temperature)and RF power and gas pressure.In order to verify the effectiveness of the model,the characteristics of the plasma are investigated using a Langmuir probe.In this paper,experimental and simulation results are presented,and the possible reasons for the discrepancies between them are given.This paper can help us understand the characteristics of RF plasma discharge,and give a basis for further R&D for an RF ion source.展开更多
Surfaces of optical elements are deposited by antireflection coatings (ARCs) to decrease the reflection of light. Surface needs treatment before depositing the ARC one of treatment processes by plasma for adhesion imp...Surfaces of optical elements are deposited by antireflection coatings (ARCs) to decrease the reflection of light. Surface needs treatment before depositing the ARC one of treatment processes by plasma for adhesion improvement and surface hardening. A comparison of RF and DC glow discharges treated CR-39 polymer films gives insight into the mechanism of these surface processes. The surface properties of the plasma-treated samples are examined by microscopy techniques include contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared (IR) spectroscopy and refractive index measurements. Results show that the plasma treatment modifies the polymer surface in both composition and morphology. It is found that the surface wettability is enhanced after plasma treatment. It is found that, RF plasma is more effective than DC plasma in CR-39 surface modification, as it implants more oxygen atoms into the surface and makes the contact angle declining to a lower level.展开更多
A simple method for measuring RF plasma parameters by means of a DC-biased Langmuir probe is developed. The object of this paper is to ensure the reliability of this method by using the other methods with different pr...A simple method for measuring RF plasma parameters by means of a DC-biased Langmuir probe is developed. The object of this paper is to ensure the reliability of this method by using the other methods with different principles. First, Langmuir probe current response on RF voltage superimposed to DC biased probe was examined in DC plasmas. Next, probe current response of DC biased probe in RF plasmas was studied and compared with the first experiment. The results were confirmed by using an emissive prove method, an ion acoustic wave method, and a square pulse response method. The method using a simple Langmuir probe is useful and convenient for measuring electron temperature , electron density , time-averaged space potential , and amplitude of space potential oscillation in RF plasmas with a frequency of the order of .展开更多
基金supported by National Natural Science Foundation of China(No.21367023)Natural Science Foundation of Gansu Province,China(No.1208RJZA161)Key Project of Young Teachers’ Scientific Research Promotion of Northwest Normal University of China(Nos.NWNU-LKQN-10-16 and NWNU-LKQN-12-9)
文摘In this paper, poly (acrylamide-co-acrylic acid) (P(AM-co-AA)) hydrogel was pre- pared in an aqueous solution by using glow-discharge electrolysis plasma (GDEP) induced copoly- merization of acrylamide (AM) and acrylic acid (AA), in which N,N'-methylenebisacrylamide (MBA) was used as a crosslinker. A mechanism for the synthesis of P(AM-co-AA) hydrogel was proposed. To optimize the synthesis condition, the following parameters were examined in detail: the discharge voltage, discharge time, the content of the crosslinker, and the mass ratio of AM to AA. The results showed that the optimum pH range for cationic dyes removal was found to be 5.0-10.0. The P(AM-co-AA) hydrogel exhibits a very high adsorption potential and the ex- perimental adsorption capacities for Crystal violet (CV) and Methylene blue (MB) were 2974.3 mg/g and 2303.6 mg/g, respectively. The adsorption process follows a pseudo-second-order kinetic model. In addition, the adsorption mechanism of P(AM-co-AA) hydrogel for cationic dyes was also discussed.
基金financially supported by National Natural Science Foundation of China(NSFC)(Nos.12275043 and 11935005)the Fundamental Research Funds for the Central Universities(No.DUT21TD104)China Scholarship Council(No.202106060085)。
文摘The effect of a negative DC bias,|V_(dc)|,on the electrical parameters and discharge mode is investigated experimentally in a radiofrequency(RF)capacitively coupled Ar plasma operated at different RF voltage amplitudes and gas pressures.The electron density is measured using a hairpin probe and the spatio-temporal distribution of the electron-impact excitation rate is determined by phase-resolved optical emission spectroscopy.The electrical parameters are obtained based on the waveforms of the electrode voltage and plasma current measured by a voltage probe and a current probe.It was found that at a low|V_(dc)|,i.e.inα-mode,the electron density and RF current decline with increasing|V_(dc)|;meanwhile,the plasma impedance becomes more capacitive due to a widened sheath.Therefore,RF power deposition is suppressed.When|V_(dc)|exceeds a certain value,the plasma changes toα–γhybrid mode(or the discharge becomes dominated by theγ-mode),manifesting a drastically growing electron density and a moderately increasing RF current.Meanwhile,the plasma impedance becomes more resistive,so RF power deposition is enhanced with|V_(dc)|.We also found that the electrical parameters show similar dependence on|V_(dc)|at different RF voltages,andα–γmode transition occurs at a lower|V_(dc)|at a higher RF voltage.By increasing the pressure,plasma impedance becomes more resistive,so RF power deposition and electron density are enhanced.In particular,theα–γmode transition tends to occur at a lower|V_(dc)|with increase in pressure.
文摘The plasma density enhancement outside hollow electrodes in capacitively coupled radio-frequency(RF) discharges is investigated by a two-dimensional(2D) particle-in-cell/Monte-Carlo collision(PIC/MCC) model. Results show that plasma exists inside the cavity when the sheath inside the hollow electrode hole is fully collapsed, which is an essential condition for the plasma density enhancement outside hollow electrodes. In addition, the existence of the electron density peak at the orifice is generated via the hollow cathode effect(HCE), which plays an important role in the density enhancement. It is also found that the radial width of bulk plasma at the orifice affects the magnitude of the density enhancement, and narrow radial plasma bulk width at the orifice is not beneficial to obtain high-density plasma outside hollow electrodes.Higher electron density at the orifice, combined with larger radial plasma bulk width at the orifice,causes higher electron density outside hollow electrodes. The results also imply that the HCE strength inside the cavity cannot be determined by the magnitude of the electron density outside hollow electrodes.
基金supported by National Natural Science Foundation of China (Nos. 11475103 and 81200805)Beijing Natural Science Foundation (No. 7162204)
文摘Improvement of the bonding strength and durability between the dentin surface and the composite resin is a challenging job in dentistry. In this paper, a radio-frequency atmosphericpressure glow discharge(RF-APGD) plasma jet is employed for the treatment of the acid-etched dentin surfaces used for the composite restoration. The properties of the plasma treated dentin surfaces and the resin–dentin interfaces are analyzed using the x-ray photoemission spectroscopy, contact angle goniometer, scanning electron microscope and microtensile tester.The experimental results show that, due to the abundant chemically reactive species existing in the RF-APGD plasma jet under a stable and low energy input operating mode, the contact angle of the plasma-treated dentin surfaces decreases to a stable level with the increase of the atomic percentage of oxygen in the specimens; the formation of the long resin tags in the scattered clusters and the hybrid layers at the resin–dentin interfaces significantly improve the bonding strength and durability. These results indicate that the RF-APGD plasma jet is an effective tool for modifying the chemical properties of the dentin surfaces, and for improving the immediate bonding strength and the durability of the resin-dentin bonding in dentistry.
文摘Spherical powders with good flowability and high stacking density are mandatory for powder bed additive manufacturing. Nevertheless, the preparation of spherical refractory tungsten and tungsten alloy powders is a formidable task. In this paper, spherical refractory metal powders processed by high-energy stir ball milling and RF inductively coupled plasma were investigated. By utilizing the technical route, pure spherical tungsten powders were prepared successfully, the flowability increased from 10.7 s/50 g to 5.5 s/50 g and apparent density increased from 6.916 g cm-3 to 11.041 g cm-3. Alloying element tantalum can reduce the tendency to micro- crack during tungsten laser melting and rapid solidification process. Spherical W-6Ta (%wt) powders were prepared in this way, homogeneous dispersion of tantalum in a tungsten matrix occurred but a small amount of flake-like shape particles appeared after high-energy stir ball milling. The flake-like shape particles can hardly be spheroidized in subsequent RF inductively coupled plasma process, might result from the unique suspended state of flaky particles under complex electric and magnetic fields as well as plasma-particle heat exchange was different under various turbulence models. As a result, the flake-like shape particles cannot pass through the high-temperature area of thermal plasma torch and cannot be spheroidized properly.
文摘This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc discharge sources. Due to the absence of hotfilaments they exhibit an inherent simplicity both in mechanical and electrical aspects andconsequently offer advantages in terms of cost savings, gain in availability and reliability andreduced maintenance. This renders the RF plasma source attractive for any long pulse (> 10 sec) NBIsystem and in particular for the ITER NBI system. The latter, however, requires that the RF plasmasource is also capable of delivering negative rather than positive hydrogen ions. In the first partof the paper the types, characteristics and operation experience of RF plasma sources for positiveions in operation are described. The second part is devoted to the development for ITER NBI: thebasic requirements, physics and technology issues and the present status are discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11472306,51336011,and 51407197)
文摘The electric and plasma characteristics of RF discharge plasma actuation under varying pressure have been inves- tigated experimentally. As the pressure increases, the shapes of charge-voltage Lissajous curves vary, and the discharge energy increases. The emission spectra show significant difference as the pressure varies. When the pressure is 1000 Pa, the electron temperature is estimated to be 4.139 eV, the electron density and the vibrational temperature of plasma are /peak /lPeak which describes the electron temper- 4.71 x 10^11 cm-3 and 1.27 eV, respectively. The ratio of spectral lines "391.4/'380.5 ature hardly changes when the pressure varies between 5000-30000 Pa, while it increases remarkably with the pressure below 5000 Pa, indicating a transition from filamentary discharge to glow discharge. The characteristics of emission spec- trum are obviously influenced by the loading power. With more loading power, both of the illumination and emission spectrum intensity increase at 10000 Pa. The pin-pin electrode RF discharge is arc-like at power higher than 33 W, which results in a macroscopic air temperature increase.
基金supported by the Scientific Foundation from Ministry of Education of China (No.N090305004)Doctor Startup Foundation Program of Liaoning Province (No.20111008)
文摘We developed a one-dimensional hybrid model to simulate the DC/RF combined driven capacitively coupled plasma for argon discharges. The numerical results are used to analyze the influence of the DC source on the plasma density distribution, ion energy distributions (IEDs) and ion angle distributions (IADs) on both the RF and DC electrodes. The increase in DC voltage drives more high-energy ions to the electrode applied to the DC source, which makes the IEDs at the DC electrode shift towards higher energy, and the peaks in the IADs shift towards small angle regions. At the same time, it also decreases the ion energy at the RF electrode and enlarges the incident angles of the ions, which strike the RF electrode.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2011GB108011 and 2010GB103001)the Major International(Regional) Project Cooperation and Exchanges(No.11320101005)
文摘Hα(Balmer-alpha), Hβ (Balmer-beta) and Hγ (Balmer-gamma) spectral line inten- sities in atomic hydrogen plasma are investigated by using a high-power RF source. The intensities of the Hα, Hβ and Hγ spectral lines are detected by increasing the input power (0-6 kW) of ICPs (inductively coupled plasmas). With the increase of net input power, the intensity of Hα im- proves rapidly (0-2 kW), and then reaches its dynamic equilibrium; the intensities of Hβ can be divided into three processes: obvious increase (0-2 kW), rapid increase (2-4 kW), almost constant (4-6 kW); while the intensities of Hγ increase very slowly. The energy levels of the excited hydro- gen atoms and the splitting energy levels produced by an obvious Stark effect play an important role in the results.
文摘In previous studies on plasma-particle interaction, as far as we know, the rf plasma flow and temperature fields are all simulated by the non-self-consistent one-dimensional electromagnetic (1-D EM) field model. In the present paper, the complete self-consistent two-dimensional electromagnetic (2-D EM) field model in- corporating the axial Lorentz force component, which is neglected in the 1-D model, is firstly adopted to calculate the aluminium particle trajectory and thermal history in atmospheric rf Ar plasma with the particle evaporation effect included. The cru- cial effect of reverse flow within the coil region on the particle trajectory is discovered and the results show that the 2-D EM field model must be adopted instead of the 1-D model when the plasma-particle interaction is studied. The effect of carrier gas flux on the particle movement and heating are also studied, resulting in some useful conclusions for both plasma theory and application.
基金supported by National Natural Science Foundation of China(Nos.11405218,11325524,11375235 and 11261140327)in part by the National Magnetic Confinement Fusion Science Program of China(Nos.2013GB111002,2013GB112001 and 2013GB112010)the Program of Fusion Reactor Physics and Digital Tokamak with the CAS"One-Three-Five"Strategic Planning
文摘The tokamak plasma flows induced by the local radio frequency (RF) forces in the core region are analyzed. The effective components of local RF forces are composed of the momentum absorption term and the resonant parallel momentum transport term (i.e. the parallel component of the resonant ponderomotive forces). Different momentum balance relations are em- ployed to calculate the plasma flows depending on different assumptions of momentum transport. With the RF fields solved from RF simulation codes, the toroidal and poloidal flows by these forces under the lower hybrid current drive and the mode conversion ion cyclotron resonance heating on EAST-like plasmas are evaluated.
基金supported by the Beijing Municipal Education Commission of China(No.KM201010015005)Beijing Key Laboratory of Printing & Packaging Materials and Technology of Beijing Institute of Graphic Communication of China(No.KF201005)
文摘Measurement of the oxygen dissociation fraction in RF low pressure oxygen/argon plasma using optical emission spectrometry is presented. The oxygen dissociation fraction and its evolutions as functions of operational parameters were determined using argon as the actinometer. At a pressure of 30 Pa, the oxygen dissociation fraction decreased from 13.4% to 9.5% as the input power increased from 10 W to 70 W. At an input power of 50 W, the oxygen dissociation fraction decreased from 12.3% to 7.7% when the gas pressure increased from 10 Pa to 40 Pa. The influences of operational parameters on the generation of atomic oxygen were also discussed.
基金supported by Joint Fund for Equipment Preresearch and Aerospace Science and Technology(No.6141B061203)。
文摘In this study,numerical simulation and discharge current tests were conducted on an inductively coupled radio frequency(RF)plasma cathode.Numerical simulations and experimental measurements were performed to study the factors influencing the electron extraction characteristics,including the gas type,gas flow,input power and extracting voltage.The simulation results were approximately consistent with the experimental results.We experimentally found that the RF input power mainly determines the extracted electron current.An electron current greater than 1 A was acquired at 270 W(RF input power),2.766 sccm(xenon gas).Our results prove that an inductively coupled RF plasma cathode can be reasonable and feasible,particularly for low power electric propulsion devices.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10376003 and 10572035).
文摘The RF electric field penetration and the power deposition into planar-type inductively coupled plasmas in low-pressure discharges have been studied by means of a self-consistent model which consists of Maxwell equations combined with the kinetic equation of electrons. The Maxwell equations are solved based on the expansion of the Fourier-Bessel series for determining the RF electric field. Numerical results show the influence of a non-Maxwellian electron energy distribution on the RF electric field penetration and the power deposition for different coil currents. Moreover, the two-dimensional spatial profiles of RF electric field and power density are also shown for different numbers of RF coil turns.
基金National Natural Science Foundation of China(Nos.11675216,11905248,11975261,11975262,11975263,and 11975264)the Key Program of Research and Development of Hefei Science Center,CAS(Contract No.2016HSC-KPRD002)the National Key R&D Program of China(Nos.2017YFE0300101,2017YFE0300103,and 2017YFE0300503).
文摘A radio frequency(RF)driven ion source is a very important component of a neutral beam injector for large magnetic confinement fusion devices.In order to study the key technology and physics of an RF driven ion source for a neutral beam injector in China,an RF ion source test facility was developed at the Institute of Plasma Physics,Chinese Academy of Sciences.In this paper,a two-dimensional fluid model is used to simulate the fundamental physical characteristics of RF plasma discharge.Simulation results show the relationship of the characteristics of plasma(such as electron density and electron temperature)and RF power and gas pressure.In order to verify the effectiveness of the model,the characteristics of the plasma are investigated using a Langmuir probe.In this paper,experimental and simulation results are presented,and the possible reasons for the discrepancies between them are given.This paper can help us understand the characteristics of RF plasma discharge,and give a basis for further R&D for an RF ion source.
文摘Surfaces of optical elements are deposited by antireflection coatings (ARCs) to decrease the reflection of light. Surface needs treatment before depositing the ARC one of treatment processes by plasma for adhesion improvement and surface hardening. A comparison of RF and DC glow discharges treated CR-39 polymer films gives insight into the mechanism of these surface processes. The surface properties of the plasma-treated samples are examined by microscopy techniques include contact angle measurements, scanning electron microscopy (SEM), atomic force microscopy (AFM), infrared (IR) spectroscopy and refractive index measurements. Results show that the plasma treatment modifies the polymer surface in both composition and morphology. It is found that the surface wettability is enhanced after plasma treatment. It is found that, RF plasma is more effective than DC plasma in CR-39 surface modification, as it implants more oxygen atoms into the surface and makes the contact angle declining to a lower level.
文摘A simple method for measuring RF plasma parameters by means of a DC-biased Langmuir probe is developed. The object of this paper is to ensure the reliability of this method by using the other methods with different principles. First, Langmuir probe current response on RF voltage superimposed to DC biased probe was examined in DC plasmas. Next, probe current response of DC biased probe in RF plasmas was studied and compared with the first experiment. The results were confirmed by using an emissive prove method, an ion acoustic wave method, and a square pulse response method. The method using a simple Langmuir probe is useful and convenient for measuring electron temperature , electron density , time-averaged space potential , and amplitude of space potential oscillation in RF plasmas with a frequency of the order of .