自由活塞发动机(Free Piston Linear Generator,以下称FPLG)具有结构简单,效率高,适应燃料多的优点。由于取消了曲柄连杆机构,活塞的位置控制是实现自由活塞发动机稳定运行的关键。本文基于Simulink建立了机械-流体-电控耦合系统模型,并...自由活塞发动机(Free Piston Linear Generator,以下称FPLG)具有结构简单,效率高,适应燃料多的优点。由于取消了曲柄连杆机构,活塞的位置控制是实现自由活塞发动机稳定运行的关键。本文基于Simulink建立了机械-流体-电控耦合系统模型,并用GT-Power及样机倒拖试验数据进行流体部分的验证。针对FPLG的非稳定状态建立了仿真模型,着重研究FPLG运行过程中换气,燃烧过程的不稳定情况,及其对FPLG运行特性的影响。展开更多
The ion saturation current is very important in probe theory, which can be used to measure the electron temperature and the floating potential. In this work, the effects of energetic ions on the ion saturation current...The ion saturation current is very important in probe theory, which can be used to measure the electron temperature and the floating potential. In this work, the effects of energetic ions on the ion saturation current are studied via particle-in-cell simulations. It is found that the energetic ions and background ions can be treated separately as different species, and they satisfy their individual Bohm criterion at the sheath edge. It is shown that the energetic ions can significantly affect the ion saturation current if their concentration is greater than root T-e/(gamma T-i2(i2)), where T-e is the electron temperature, and gamma(i2) and T-i2 represent the polytropic coefficient and temperature of energetic ions, respectively. As a result, the floating potential and the I-V characteristic profile are strongly influenced by the energetic ions. When the energetic ion current dominates the ion saturation current, an analysis of the ion saturation current will yield the energetic ion temperature rather than the electron temperature.展开更多
The properties of a collisionless plasma sheath are investigated by using a fluid model in which two species of positive ions and secondary electrons are taken into account. It is shown that the positive ion speeds at...The properties of a collisionless plasma sheath are investigated by using a fluid model in which two species of positive ions and secondary electrons are taken into account. It is shown that the positive ion speeds at the sheath edge increase with secondary electron emission（SEE） coefficient, and the sheath structure is affected by the interplay between the two species of positive ions and secondary electrons. The critical SEE coefficients and the sheath widths depend strongly on the positive ion charge number, mass and concentration in the cases with and without SEE. In addition, ion kinetic energy flux to the wall and the impact of positive ion species on secondary electron density at the sheath edge are also discussed.展开更多
The structure of the sheath in the presence of energetic particles is investigated in the multi-fluid framework. Based on the orbital motion limited（OML） theory, the dust grain charging inside the sheath of plasma c...The structure of the sheath in the presence of energetic particles is investigated in the multi-fluid framework. Based on the orbital motion limited（OML） theory, the dust grain charging inside the sheath of plasma containing energetic particles is examined for the carbon wall, and then the effect of the energetic particles on the stationary dust particle inside the sheath is discussed through the trapping potential energy. It is found that with the increase of energetic ion concentration or energy,the size of dust staying in levitation equilibrium decreases and the levitating position is much closer to the wall. In the case of deuterium ions as energetic ions, the bigger dust particle can be trapped by the sheath than in the case of hydrogen ions as energetic ions. When the energetic electron component is present, the levitating position of dust particle in the sheath depends strongly on the energetic electron. The levitating dust particle is closer to the wall as the energetic electron energy or concentration is increased. In addition, with the increase of temperature of thermal background ion, the size of dust particle trapped by the sheath decreases and the levitating positions of dust particles with the same size radius inside the sheath move toward the wall. Our results can be helpful in investigating the property of the sheath where the energetic particle component is present.展开更多
文摘自由活塞发动机(Free Piston Linear Generator,以下称FPLG)具有结构简单,效率高,适应燃料多的优点。由于取消了曲柄连杆机构,活塞的位置控制是实现自由活塞发动机稳定运行的关键。本文基于Simulink建立了机械-流体-电控耦合系统模型,并用GT-Power及样机倒拖试验数据进行流体部分的验证。针对FPLG的非稳定状态建立了仿真模型,着重研究FPLG运行过程中换气,燃烧过程的不稳定情况,及其对FPLG运行特性的影响。
基金Supported by the Program of Fusion Reactor Physics and Digital Tokamak with the Chinese Academy of Sciences'One-Three Five'Strategic Planningthe JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(NSFC No 11261140328 and NRF No 2012K2A2A6000443)+1 种基金the National ITER Program of China under Grant No 2015GB101003the National Natural Science Foundation of China under Grant Nos 11405215,11475223 and 11505236
文摘The ion saturation current is very important in probe theory, which can be used to measure the electron temperature and the floating potential. In this work, the effects of energetic ions on the ion saturation current are studied via particle-in-cell simulations. It is found that the energetic ions and background ions can be treated separately as different species, and they satisfy their individual Bohm criterion at the sheath edge. It is shown that the energetic ions can significantly affect the ion saturation current if their concentration is greater than root T-e/(gamma T-i2(i2)), where T-e is the electron temperature, and gamma(i2) and T-i2 represent the polytropic coefficient and temperature of energetic ions, respectively. As a result, the floating potential and the I-V characteristic profile are strongly influenced by the energetic ions. When the energetic ion current dominates the ion saturation current, an analysis of the ion saturation current will yield the energetic ion temperature rather than the electron temperature.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11475220 and 11405208)the Program of Fusion Reactor Physics and Digital Tokamak with the CAS"One-Three-Five"Strategic Planning+1 种基金the National ITER Program of China(Grant No.2015GB101003)the Higher Education Natural Science Research Project of Anhui Province,China(Grant No.2015KJ009)
文摘The properties of a collisionless plasma sheath are investigated by using a fluid model in which two species of positive ions and secondary electrons are taken into account. It is shown that the positive ion speeds at the sheath edge increase with secondary electron emission（SEE） coefficient, and the sheath structure is affected by the interplay between the two species of positive ions and secondary electrons. The critical SEE coefficients and the sheath widths depend strongly on the positive ion charge number, mass and concentration in the cases with and without SEE. In addition, ion kinetic energy flux to the wall and the impact of positive ion species on secondary electron density at the sheath edge are also discussed.
基金Project supported by the National Natural Science Foundation of China(Grant No.11475223)the National Magnetic Confinement Fusion Science Program of China(Grant No.2015GB101003)the JSPS-NRF-NSFC A3 Foresight Program in the field of Plasma Physics(Grant Nos.11261140328 and2012K2A2A6000443)
文摘The structure of the sheath in the presence of energetic particles is investigated in the multi-fluid framework. Based on the orbital motion limited（OML） theory, the dust grain charging inside the sheath of plasma containing energetic particles is examined for the carbon wall, and then the effect of the energetic particles on the stationary dust particle inside the sheath is discussed through the trapping potential energy. It is found that with the increase of energetic ion concentration or energy,the size of dust staying in levitation equilibrium decreases and the levitating position is much closer to the wall. In the case of deuterium ions as energetic ions, the bigger dust particle can be trapped by the sheath than in the case of hydrogen ions as energetic ions. When the energetic electron component is present, the levitating position of dust particle in the sheath depends strongly on the energetic electron. The levitating dust particle is closer to the wall as the energetic electron energy or concentration is increased. In addition, with the increase of temperature of thermal background ion, the size of dust particle trapped by the sheath decreases and the levitating positions of dust particles with the same size radius inside the sheath move toward the wall. Our results can be helpful in investigating the property of the sheath where the energetic particle component is present.
