To improve the performance of a metal ion plasma jet in vacuum discharge, an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper. Discharge characteristics and generation character...To improve the performance of a metal ion plasma jet in vacuum discharge, an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper. Discharge characteristics and generation characteristics of plasma of the electrode are investigated, effects of diameter of insulating sleeve, variety of cathode material and length of the insulating sleeve on characteristics of metal ion plasma jet are discussed. Results indicate that a directional and steady plasma jet is formed by using the novel electrode with insulating sleeve under high vacuum conditions. Moreover, the properties of metal ion plasma jet are improved by using the aluminum cathode and thin and long insulating sleeve. The study provides strong support for research of vacuum metal ion plasma thruster and ion implantation technology.展开更多
The plasma-jet triggered gas switch （PJTGS） could operate at a low working coefficient with a low jitter. We observed and analyzed the discharge process of the PJTGS at the lowest working coefficient of 47% with the...The plasma-jet triggered gas switch （PJTGS） could operate at a low working coefficient with a low jitter. We observed and analyzed the discharge process of the PJTGS at the lowest working coefficient of 47% with the trigger voltage of 40 kV and the pulse energy of 2 J to evaluate the effect of the plasma jet. The temporal and spatial evolution and the optical emission speclrum of the plasma jet were captured. And the spraying delay time and outlet velocity under different gas pressures were investigated. In addition, the particle in cell with Monte Carlo collision was employed to obtain the particle distribution of the plasma jet varying with time. The results show that, the plasma jet generated by spark discharge is sprayed into a spark gap within tens of nanoseconds, and its outlet velocity could reach 104 m s-1. The plasma jet plays a non-penetrating inducing role in the triggered discharge process of the PJTGS. On the one hand, the plasma jet provides the initial electrons needed by the discharge; on the other hand, a large number of electrons focusing on the head of the plasma jet distort the electric field between the head of the plasma jet and the opposite electrode. Therefore, a fast discharge originated from the plasma jet is induced and quickly bridges two electrodes.展开更多
In this work, a typical pin-to-pin plasma synthetic jet in static air is excited by a pulsed DC power supply. The influences of the pulse rising time, the amplitude and the repetition frequency of the pulse voltage on...In this work, a typical pin-to-pin plasma synthetic jet in static air is excited by a pulsed DC power supply. The influences of the pulse rising time, the amplitude and the repetition frequency of the pulse voltage on the jet flow have been investigated. First, using a high-speed Schlieren imaging technique, the induced shock waves and the fast jet flow generated by the plasma synthetic jet are characterized. With a deposited energy of 44 m J per pulse, the velocity of the shock wave and the maximum velocity of the jet flow reach 320 m s-1 and 100 m s-1,respectively. Second, when the applied voltage increases from 12.8 kV to 16 kV, the maximum jet velocity increases from 66 m s-1 to 93 m s-1. On the other hand, as the pulse rising time varies from 50 ns to 500 ns, or the pulse repetition frequency increases from 5 Hz to 40 Hz, the jet velocity induced by the plasma synthetic jet is weakly dependent. In addition, a comparative study of the plasma synthetic jets using three commercial pulsed power supplies(XJ-15, NPG-18, and PG-30) is implemented. It reveals that the maximum jet velocity of 120 m s-1 is obtained in the case of PG-30, with the longest pulse rising time and the lowest breakdown voltage, while the maximum velocity of 33 m s-1 is detected in the case of NPG-18, even though it has the shortest pulse rising time and the highest breakdown voltage.展开更多
Spark discharge plasma synthetic jets(SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting...Spark discharge plasma synthetic jets(SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting balance at a 20 m/s wind speed. The aim was to explore the SPJ's effect on airfoil aerodynamic by examining SPJ generators' position along the chordwise and the jet flow direction about the chord. Near the wing leading edge, two SPJ generators raised the stall angle by 2° and increased the maximum lift coefficient by 9%. The drag coefficient was decreased by 33.1%, and the lift-drag ratio was increased by 104.2% at an angle of attack above 16°. The rolling-moment coefficient was modified by 0.002, and the yawing-moment coefficient was changed by 0.0007 at angles of attack in the range of 0°–16°. The results showed that SPJs can control wing aerodynamic forces at a high angle of attack and moments at a low angle of attack.展开更多
The paper reviews the results of investigations of the low-current atmospheric-pressure discharges in gas flow.The attention is focused on the discharges in electrode systems of coaxial plasmatron and of so-called gli...The paper reviews the results of investigations of the low-current atmospheric-pressure discharges in gas flow.The attention is focused on the discharges in electrode systems of coaxial plasmatron and of so-called gliding arc.It is demonstrated that a considerable fraction of discharge current is carried by a plasma column operating in a regime of normal glow discharge with occasional transitions to spark.The nature of glow-to-spark transition is discussed.Beside the plasma column,a weakly ionized gas fills in the interelectrode gap and forms a plasma jet at the exit of electrode system.The jet contains the active chemical particles that play important role in different discharge applications.The applications in plasma assisted combustion systems,for surface treatment with a usage of plasma jet,and for biology and medicine are considered.展开更多
基金supported by National Natural Science Foundation of China(No.51577011)
文摘To improve the performance of a metal ion plasma jet in vacuum discharge, an anode-insulated cone-cylinder electrode with insulating sleeve is proposed in this paper. Discharge characteristics and generation characteristics of plasma of the electrode are investigated, effects of diameter of insulating sleeve, variety of cathode material and length of the insulating sleeve on characteristics of metal ion plasma jet are discussed. Results indicate that a directional and steady plasma jet is formed by using the novel electrode with insulating sleeve under high vacuum conditions. Moreover, the properties of metal ion plasma jet are improved by using the aluminum cathode and thin and long insulating sleeve. The study provides strong support for research of vacuum metal ion plasma thruster and ion implantation technology.
文摘The plasma-jet triggered gas switch （PJTGS） could operate at a low working coefficient with a low jitter. We observed and analyzed the discharge process of the PJTGS at the lowest working coefficient of 47% with the trigger voltage of 40 kV and the pulse energy of 2 J to evaluate the effect of the plasma jet. The temporal and spatial evolution and the optical emission speclrum of the plasma jet were captured. And the spraying delay time and outlet velocity under different gas pressures were investigated. In addition, the particle in cell with Monte Carlo collision was employed to obtain the particle distribution of the plasma jet varying with time. The results show that, the plasma jet generated by spark discharge is sprayed into a spark gap within tens of nanoseconds, and its outlet velocity could reach 104 m s-1. The plasma jet plays a non-penetrating inducing role in the triggered discharge process of the PJTGS. On the one hand, the plasma jet provides the initial electrons needed by the discharge; on the other hand, a large number of electrons focusing on the head of the plasma jet distort the electric field between the head of the plasma jet and the opposite electrode. Therefore, a fast discharge originated from the plasma jet is induced and quickly bridges two electrodes.
基金partially supported by National Natural Science Foundation of China (No. 51607090)the Natural Science Foundation of Jiangsu Province (No. BK20160796)+1 种基金Fundamental Research Funds for the Central Universities (No. XCA17003-03)the Delta Research and EducationalFoundation (No. DREG2017008)
文摘In this work, a typical pin-to-pin plasma synthetic jet in static air is excited by a pulsed DC power supply. The influences of the pulse rising time, the amplitude and the repetition frequency of the pulse voltage on the jet flow have been investigated. First, using a high-speed Schlieren imaging technique, the induced shock waves and the fast jet flow generated by the plasma synthetic jet are characterized. With a deposited energy of 44 m J per pulse, the velocity of the shock wave and the maximum velocity of the jet flow reach 320 m s-1 and 100 m s-1,respectively. Second, when the applied voltage increases from 12.8 kV to 16 kV, the maximum jet velocity increases from 66 m s-1 to 93 m s-1. On the other hand, as the pulse rising time varies from 50 ns to 500 ns, or the pulse repetition frequency increases from 5 Hz to 40 Hz, the jet velocity induced by the plasma synthetic jet is weakly dependent. In addition, a comparative study of the plasma synthetic jets using three commercial pulsed power supplies(XJ-15, NPG-18, and PG-30) is implemented. It reveals that the maximum jet velocity of 120 m s-1 is obtained in the case of PG-30, with the longest pulse rising time and the lowest breakdown voltage, while the maximum velocity of 33 m s-1 is detected in the case of NPG-18, even though it has the shortest pulse rising time and the highest breakdown voltage.
文摘Spark discharge plasma synthetic jets(SPJs) have been used for the active flow control study on an NACA 0021 straight-wing model in a wind tunnel. The model forces and moments were measured using a six-component sting balance at a 20 m/s wind speed. The aim was to explore the SPJ's effect on airfoil aerodynamic by examining SPJ generators' position along the chordwise and the jet flow direction about the chord. Near the wing leading edge, two SPJ generators raised the stall angle by 2° and increased the maximum lift coefficient by 9%. The drag coefficient was decreased by 33.1%, and the lift-drag ratio was increased by 104.2% at an angle of attack above 16°. The rolling-moment coefficient was modified by 0.002, and the yawing-moment coefficient was changed by 0.0007 at angles of attack in the range of 0°–16°. The results showed that SPJs can control wing aerodynamic forces at a high angle of attack and moments at a low angle of attack.
基金Project supported by Russian Foundation for Basic Research(under Grants 11-08-00671,13-08-98110)
文摘The paper reviews the results of investigations of the low-current atmospheric-pressure discharges in gas flow.The attention is focused on the discharges in electrode systems of coaxial plasmatron and of so-called gliding arc.It is demonstrated that a considerable fraction of discharge current is carried by a plasma column operating in a regime of normal glow discharge with occasional transitions to spark.The nature of glow-to-spark transition is discussed.Beside the plasma column,a weakly ionized gas fills in the interelectrode gap and forms a plasma jet at the exit of electrode system.The jet contains the active chemical particles that play important role in different discharge applications.The applications in plasma assisted combustion systems,for surface treatment with a usage of plasma jet,and for biology and medicine are considered.
