Analysis of flow separation control using nanosecond-pulse discharge plasma actuators on a flying wing

Abstract Dielectric barrier discharge (DBD) plasma is one of most promising flow control method for its several advantages. The present work investigates the control authority of nanosecond pulse DBD plasma actuators on a flying wing model’s aerodynamic characteristics. The aerodynamic forces and moments are studied by means of experiment and numerical simulation. The numerical simulation results are in good agreement with experiment results. Both results indicate that the NS-DBD plasma actuators have negligible effect on aerodynamic forces and moment at the angles of attack smaller than 16°. However, significant changes can be achieved with actuation when the model’s angle of attack is larger than 16° where the flow separation occurs. The spatial flow field structure results from numerical simulation suggest that the volumetric heat produced by NS-DBD plasma actuator changes the local temperature and density and induces several vortex structures, which strengthen the mixing of the shear layer with the main flow and delay separation or even reattach the separated flow.     

托卡马克超声分子束注入加料的进展

超声分子束注入作为一种新的托卡马克加料方法由作者在1992年首次提出并于当年在中国环流器一号(HL-1)装置演示成功,随后相继应用于中国环流器新一号(HL-1M)和中国科学院超导托卡马克HT-7装置。超声分子束注入等离子体呈现出电子密度峰化和温度中空分布的特征;等离子体流极向旋转速度提高,边缘扰动被抑制,等离子体能量约束得到改善。加料效率较常规脉冲送气提高一倍,而滞留器壁的粒子大为减少。近期开展的高气压氢超分子束注入实验,在束流中发现团簇流,可注入等离子体中心区域。多脉冲分子束注入形成电子密度的阶跃上升,如同冰弹丸注入效果。近年来该项技术已陆续应用于国外大型托卡马克和仿星器,是核聚变装置稳态运行的一种有效的加料方法。     

Influence of heating effect in Thomson scattering diagnosis of laser-produced plasmas in air

A state diagnosis of laser-produced plasma in air generated by a 1064 nm pulse laser was investigated by the Thomson scattering(TS) method. The evolutions of the electron temperature and electron density were obtained as a function of the time delay which ranged from300–3200 ns. The heating effect produced by the 532 nm probe beam with different energies on the air plasma at different interaction times was further studied using a time-resolved optical emission spectroscopy technique. The influence of the probe beam on the electron density was found to be negligible, whereas its influence on electron temperature is evident. In addition, the heating effect of the probe beam on the plasma strongly depends on the energy of the probe beam, and gradually weakens with increasing time delay. Our results are helpful for further understanding the TS method and its application in plasma diagnostics.     

The plume diagnostics of 30 cm ion thruster with an advanced plasma diagnostics system

In order to achieve a better understanding of plume characteristics of LIPS-300 ion thruster, the beam current density, ion energy and electron number density of LIPS-300 ion thruster plume are studied with an Advanced Plasma Diagnostics System(APDS) which allows for simultaneous in situ measurements of various properties characterizing ion thruster, such as plasma density, plasma potential, plasma temperature and ion beam current densities, ion energy distribution and so on. The results show that the beam current density distribution has a double‘wing' shape. The high energy ions were found in small scan angle, while low energy ions were found in greater scan angle. Electron number density has a similar shape with the beam current density distribution.     

Control of Beam Energy and Flux Ratio in an Ion-Beam-Background Plasma System Produced in a Double Plasma Device

Plasmas containing ion beams have various applications both in plasma technology and in fundamental research. The ion beam energy and flux are the two factors characterizing the beam properties. Previous studies have not achieved the independent adjustment of these two parameters. In this paper, an ion-beam-background-plasma system was produced with hotcathode discharge in a double plasma device separated by two adjacent grids, with which the beam energy and flux ratio(the ratio between the beam flux and total ion flux) can be controlled independently. It is shown that the discharge voltage(i.e., voltage across the hot-cathode and anode) and the voltage drop between the two separation grids can be used to effectively control the beam energy while the flux ratio is not affected by these voltages. The flux ratio depends sensitively on hot-filaments heating current whose influence on the beam energy is relatively weak,and thus enabling approximate control of the flux ratio     

Electrical Characteristics of Pulsed Corona Discharge Plasmas in Chitosan Solution

Pulsed discharge plasma has exhibited active potential to prepare low molecular weight chitosan. In the present study, the viscosity of ehitosan solution was decreased noticeably after treated with pulsed corona discharge plasma. An experimental investigation on electrical characteristics of pulsed corona discharge plasma in chitosan solution was conducted with a view toward getting insight into discharge process. Factors affecting I-V curve, single pulse injec- tion energy and pulse width were studied. Experimental results showed positive effect of pulsed peak voltage on discharge plasma in chitosan solution. Pulse-forming capacitor greatly influenced the discharge form, and 4 nF was observed as a suitable value for efficiently generating stable discharge plasmas. As the electrode distance was larger than 10 ram, it had slight impact on dis- charge plasma due to the excellent conductive-property of chitosan solution. The injection energy significantly increased with air flow rate, while the pulse width hardly changed as the air flow rate increased from 0.5 m^3/h to 1.0 m^3/h. This study is expected to provide reference for promoting the application of pulsed corona discharge plasma to ehitosan solution treatment.     

Analysis of Power Deposition on Heat Load Components for EAST Neutral Beam Injector

Neutral beam injection is recognized as one of the most effective means of plasma heating. The target values of EAST Neutral beam injector (NBI) are beam energy 50–80 keV, injection beam total power 2–4 MW, beam pulse width 10–100 s. The beam power will deposit on the beam collimator due to the beam divergence and it will cause heat damage to heat load components, or even destroy the entire NBI system. In order to decrease the risk, the beam power deposited on heat load components should be assessed. In this article, the percent of power deposition on each heat load components has been calculated using Gaussian beam transmission model. Comparison of the results measured with water flow calorimeter and calculated results shows the beam transmission model has relative good agreement with real distribution. The results can direct the operation parameter optimization of EAST NBI.     

Properties of Ion Beams Generated by Nitrogen Plasma Focus

Numerical experiments have been systematically carried out using the modified Lee model code on various plasma focus devices operated with nitrogen gas. The ion beam properties (ion beam energy, ion beam flux, ion beam fluence, beam ion number, ion beam current, power flow density, and damage factor) of the plasma focus have been studied versus gas pressure for each plasma focus device. The results show that, for these studied plasma focus devices, the mean ion energies decrease with increasing gas pressure, while the beam ion number increases with higher pressure. The fluence, flux, ion current, power flow density and damage factor have maximum values at the optimum pressure. It is shown that, the maximum power flow densities range from 10¹² to 10¹⁴ W m^?2 and the damage factor values reach almost 10⁹–10¹¹ W m^?2 s^0.5. The obtained results provide much needed benchmark reference values and scaling trends for ion beams of a plasma focus operated in nitrogen gas. These results could be used as an indicator for ion properties emitted from nitrogen plasma focus for various applications including material processing.     

Achievement of 100 s Long Pulse Neutral Beam Extraction in EAST Neutral Beam Injector

Neutral beam injection (NBI) is recognized as one of the most e®ective means for plasma heating. A 100 s long pulse neutral beam with 30 keV beam energy, 10 A beam current and a 100 s long pulse modulating neutral beam with 50 keV beam energy, 16 A beam current were achieved in the EAST neutral beam injector on the test-stand. The preliminary results suggest that EAST-NBI system initially possess the ability of long pulse beam extraction.     

The interaction of high-current pulse beams with plasma in a magnetic field

We have studied the interaction of an electron beam with currents up to 8.5 A and energies up to 15 keV with a plasma in a magnetic field, the intensity of which varied between 36O and 1320 Oe. We studied the energy distribution of electrons after passage of the electron beam through the plasma as a function of the beam current, residual gas pressure (air), and the intensity of the longitudinal magnetic field. We measured the intensities of the transverse and longitudinal highfrequency fields excited by the beam in the plasma; these reach about 100 V/cm and 1–2 kV/cm respectively. This proves that the high energy losses of the beam due to its passage through the plasma are caused by excitation of high-frequency vibrations.Translated from Atomnaya Énergiya, Vol. 14, No. 3, pp. 249–256, March, 1963     

An Introduction to the Supersonic Molecular Beam injection

Magnet confinement fusion plasma physics1. IntroductionThe most commonly used system for initiating andmaintaining density in present-day tokamak is gaspuffing, but its major physics issue is whether ornot the fuel introduced at the plasma boundary canpenetrate the SOL to reach the region Of the coreplasma ti.here it is needed. The fuelling efficiency ofpresence-day tokimaks inclusive of start-up is of theorder of 10% for gas puffing. The gas fuelling efficiency is dependent on the SOL thic…     

Heat Transport During H-Mode in the HL-2A Tokamak

Perturbative experiments on electron heat transport have been successfully con- ducted on the HL-2A tokamak. The pulse propagation of the electron temperature is induced by the supersonic molecular beam injection (SMBI), which has characteristics of good localization and deep deposition. A model based on the electron heat transport in cylindrical geometry has been applied to reconstruct the measured amplitude and phase profi les of the electron temperature perturbation. The results show that the heat transport is significantly reduced near the pedestal region of the H-mode plasma. In the \profi ness/resilience" region, similar heat diffusivities have been observed in L-mode and H-mode plasmas, which verifiesthe gradient-driven transport physics in tokamaks.     

氦对低活性Fe-Cr-Mn(W,V)合金辐照损伤影响

采用低能离子加速器和超高压电镜相连接复合辐照装置,研究注入He后经电子束辐照,观察低放射性Fe-Cr-Mn（W,V）合金的辐照损伤特征;研究He对辐照过程中产生二次缺陷,空洞肿胀,诱起晶界偏析的影响。实验结果证明He的存在,增加辐照初期位错密度,促进空洞核心形成及空洞肿胀增加,抑制晶界近旁溶质元素偏析。     

Research on the Peristaltic Flow Acceleration Performance of Asynchronous and Duty Cycle Pulsed DBD Plasma Actuation

Using a plexiglas plate model, the performance of peristaltic flow acceleration in- duced by multiple DBD （dielectric barrier discharge） plasma actuators was studied based on PIV （particle image velocimetry）. The asynchronous and the duty cycle pulsed actuation modes were proposed and tested. The velocity fields induced by multiple DBD plasma actuators with different phase angles and duty cycle ratios were acquired and the momentum transfer characteristics of the flow field were discussed. Consequently, the mechanism of the peristalsis-acceleration multi- ple DBD plasma actuation was analyzed. The results show that the peristaltic flow acceleration effect of multiple plasma actuators occurs mainly in paraelectric direction, and the mechanism of peristaltic flow acceleration is ejection pushing effect rather than injection pumping effect. The asynchronous and the duty cycle pulsed actuation modes can, with energy consumption increase of merely 10%, achieve 65% and 42% increase of downstream velocity, and thus are promising in velocity improvement and energy saving.     

Review of the experiments for energetic particle physics on HL-2A

This paper reviews the energetic particle(EP) experiments during electron cyclotron resonance heating(ECRH) and neutral beam injection in the HL-2 A tokamak.A number of important results are summarized,which relate to ITER physics,including the behavior of the multi-mode instability,the nonlinear interaction between wave–wave and wave–particles,the losses of EP induced by the instabilities,the effect of the EP instabilities on the thermal plasma confinement and the control of the EP instabilities by means of ECRH.Systematic experiments indicate that when the drive is great enough,the nonlinear effects and the multi-mode coexistence may play an important role,which affect the transport both of the EPs and the background plasma confinement,and these instabilities could be controlled.Some new phenomena about the EP induced instabilities discovered recently on the device,such as high frequency reversed shear Alfvén eigenmodes,Alfvénic ion temperature gradient modes,the geodesic acoustic mode induced by energetic electrons excited by interaction between tearing mode and beta induced Alfvén eigenmode and double e-fishbone in negative magnetic shear discharges etc,have also been presented in the paper.     

Energetics of Beam Driven D-Cycle Plasmas

The energetic characteristics of deuterium fueled fusion plasmas well below ignition and aided by neutral beam injection are investigated with the perspective of eventually being utilized in a fusion hybrid reactor. Particular emphasis is placed on the three modes of D-fusion cycles and on the role of the neutral beam ions as they effect the plasma energetics. Ion concentrations corresponding to steady state operation of the fusion cycles as well as total reaction rates and fusion gains are evaluated for regimes which tend to be identified with a two energy component reactor. The associated interrelation requirements on the temperature, density and magnetic confinement of the plasma are illustrated. It is shown how operational plasma constraints can be substantially relaxed by high energetic deuteron injection while retaining an energy viability sufficient for a synergetic fusion reactor concept.     

Influence of non-uniform electric field distribution on the atmospheric pressure air dielectric barrier discharge

The dielectric barrier discharge(DBD) in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments. In this paper, the influence of the electric field distribution on the uniformity of DBD is theoretically analyzed and experimentally verified. It is found that a certain degree of uneven electric field distributions can control the development of electron avalanches and regulate their transition to streamers in the gap. The discharge phenomena and electrical characteristics prove that an enhanced Townsend discharge can be formed in atmospheric-pressure air with a curved-plate electrode. The spectral analysis further confirms that the gas temperature of the plasma produced by the curved-plate electrode is close to room temperature, which is beneficial for industrial applications. This paper presents the relationship between the electron avalanche transition and the formation of a uniform DBD, which can provide some references for the development and applications of the DBD in the future.     

Commissioning of the first KSTAR neutral beam injection system and beam experiments

The neutral beam injection (NBI) system was designed to provide plasma heating and current drive for high performance and long pulse operation of the Korean Superconducting Tokamak Advanced Research (KSTAR) device using two co-current beam injection systems. Each neutral beam injection system was designed to inject three beams using three ion sources and each ion source has been designed to deliver more than 2.0 MW of deuterium neutral beam power for the 100-keV beam energy. Consequently, the final goal of the KSTAR NBI system aims to inject more than 12 MW of deuterium beam power with the two NBI for the long pulse operation of the KSTAR. As an initial step toward the long pulse (～300 s) KSTAR NBI system development, the first neutral beam injection system equipped with one ion source was constructed for the KSTAR 2010 campaign and successfully commissioned. During the KSTAR 2010 campaign, a MW-deuterium neutral beam was successfully injected to the KSTAR plasma with maximum beam energy of 90 keV and the L-H transition was observed with neutral beam heating. In recent 2011 campaign, the beam power of 1.5 MW is injected with the beam energy of 95 keV. With the beam injection, the ion and electron temperatures increased significantly, and increase of the toroidal rotation speed of the plasma was observed as well. This paper describes the design, construction, commissioning results of the first NBI system leading the successful heating experiments carried in the KSTAR 2010 and 2011 campaign and the trial of 300-s long pulse beam extraction.     

Investigation of optimum discharge characteristics and chemical activity of AC driven air plasma jet and its anticancer effect

In this study,we investigated the effects of the quartz tube diameter,air flow rate,and applied voltage on the characteristics of an air plasma jet to obtain the optimized discharge characteristics.The physicochemical properties and concentration of reactive oxygen and nitrogen species(RONS)in plasma-activated medium(PAM)were characterized to explore their chemical activity.Furthermore,we investigated the inactivation effect of air plasma jet on tumour cells and their corresponding inactivation mechanism.The results show that the tube diameter plays an important role in sustaining the voltage of the air plasma jet,and the gas flow rate affects the jet length and discharge intensity.Additionally,the air plasma jet discharge displays two modes,namely,ozone and nitrogen oxide modes at high and low gas flow rates,respectively.Increasing the voltage increases the concentration of reactive species and the length of discharge.By evaluating the viability of A549 cells under different parameters,the optimal treatment conditions were determined to be a quartz tube diameter of 4 mm,gas flow rate of 0.5 SLM,and voltage of 18 kV.Furthermore,an air plasma jet under the optimized conditions effectively enhanced the chemical activity in PAM and produced more aqueous RONS.The air plasma jet induced significant cytotoxicity in A549 cancer cells after plasma treatment.H2O2 and NO2 are regarded as key factors in promoting cell inactivation.The present study demonstrates the potential use of tumour cell therapy by atmospheric air PAM,which aids a better understanding of plasma liquid chemistry.     

不同类型电离辐射对聚醚聚氨酯材料的辐射效应

文章讨论聚醚聚氨酯材料经γ射线和电子束两种电离辐射辐照后的辐射效应。采用气相色谱、差示扫描量热分析和电子自旋共振技术，研究材料经不同类型电离辐射辐照后材料的热性能和自由基强度的变化及其辐解气体产物的种类和G值。结果表明，γ射线和电子束辐照聚醚聚氨酯材料时，二者对材料的作用机理虽相同，但能量淀积方式却不同，导致自由基数量和强度有所不同，同时材料的热性能和辐解气体小分子也存在差异。