The effect of ion motion in capillary-guided laser-driven plasma wake is investigated through rebuilding a two-dimensional analytical model.It is shown that laser pulse with the same power can excite more intense wake...The effect of ion motion in capillary-guided laser-driven plasma wake is investigated through rebuilding a two-dimensional analytical model.It is shown that laser pulse with the same power can excite more intense wakefield in the capillary of a smaller radius.When laser intensity exceeds a critical value,the effect of ion motion reducing the wakefield rises,which becomes significant with a decrease of capillary radius.This phenomenon can be attributed to plasma ions in smaller capillary obtaining more energy from the plasma wake.The dependence of the difference value between maximal scalar potential of wake for two cases of ion rest and ion motion on the radius of the capillary is discussed.展开更多
A new method of compensating for the excess micromotion along two directions in three-dimensional Coulomb crystals is reported in this paper; this method is based on shape control and optical imaging of a Coulomb crys...A new method of compensating for the excess micromotion along two directions in three-dimensional Coulomb crystals is reported in this paper; this method is based on shape control and optical imaging of a Coulomb crystal in a sectioned linear ion trap. The characteristic parameters, such as the ion numbers, temperatures, and geometric factors of different ion crystals are extracted from the images and secular motion excitation spectra. The method of controlling the shape of the ion crystals can be used in cold ion experiments, such as sympathetically cooling, structural phase transitions,and selective-control of ions, etc.展开更多
This paper reports that a cloud of laser-cooled ^40Ca^＋ is successfully trapped and manipulated in the home-built linear ion trap constructed for quantum information processing （QIP）. The frequency of the secular m...This paper reports that a cloud of laser-cooled ^40Ca^＋ is successfully trapped and manipulated in the home-built linear ion trap constructed for quantum information processing （QIP）. The frequency of the secular motion and the space charge density of the ion cloud are measured, which help knowing the characteristic of the trapping potential and are the prerequisite of QIP with the trapped ions.展开更多
We present a model which is used to study ion transport in capacitively coupled plasma （CCP） discharge driven by a radio-frequency （rf） source for an etching process. The model combines a collisional sheath model ...We present a model which is used to study ion transport in capacitively coupled plasma （CCP） discharge driven by a radio-frequency （rf） source for an etching process. The model combines a collisional sheath model with a trench model. The sheath model can calculate the ion energy distributions （IEDs） and ion angular distributions （IADs） to specify the initial conditions of the ions incident into the trench domain （a simulation area near and in the trench）. Then, considering the charging effect on the photoresist sidewalls and the rf-bias applied to the substrate, the electric potentials in the trench domain are computed by solving the Laplace equation. Finally, the trajectories, IEDs and IADs of ions impacting on the bottom of the trench are obtained using the trench model. Numerical results show that as the pressure increases, ions tend to strike the trench bottom with smaller impact energies and larger incident angles due to the collision processes, and the existence of the trench has distinct influences on the shape of the IEDs and IADs. In addition, as the bias amplitude increases, heights of both peaks decrease and the IEDs spread to a higher energy region.展开更多
This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows tow...This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows towards electrodes generate non-uniform discharging pulses. Inspection of these pulses provides useful information on ionic stream kinetics, the effective thickness of ion cover around electrodes, and the timing of ion clouds discharge pulse sequences. A finite difference time domain （FDTD） based space-charge motion simulation is used for the numerical analysis of the spatio-temporal development of ionic flows following the first Townsend avalanche, and the simulation results demonstrate expansion of the positive ion flow and compression of the negative ion flow, which results in non-uniform discharge pulse characteristics.展开更多
基金supported by National Natural Science Foundation of China(No.11247016)the Natural Science Foundation of Jiangxi Province,China(Nos.2014ZBAB202001 and 20151BAB212010)the Science Foundation for Youths of the Jiangxi Education Committee of China(No.GJJ14224)
文摘The effect of ion motion in capillary-guided laser-driven plasma wake is investigated through rebuilding a two-dimensional analytical model.It is shown that laser pulse with the same power can excite more intense wakefield in the capillary of a smaller radius.When laser intensity exceeds a critical value,the effect of ion motion reducing the wakefield rises,which becomes significant with a decrease of capillary radius.This phenomenon can be attributed to plasma ions in smaller capillary obtaining more energy from the plasma wake.The dependence of the difference value between maximal scalar potential of wake for two cases of ion rest and ion motion on the radius of the capillary is discussed.
基金supported by the National Basic Research Program of China(Grant Nos.2012CB821301 and 2010CB832803)the National Natural Science Foundation of China(Grant Nos.11004222 and 91121016)the Fund from Chinese Academy of Sciences
文摘A new method of compensating for the excess micromotion along two directions in three-dimensional Coulomb crystals is reported in this paper; this method is based on shape control and optical imaging of a Coulomb crystal in a sectioned linear ion trap. The characteristic parameters, such as the ion numbers, temperatures, and geometric factors of different ion crystals are extracted from the images and secular motion excitation spectra. The method of controlling the shape of the ion crystals can be used in cold ion experiments, such as sympathetically cooling, structural phase transitions,and selective-control of ions, etc.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10774161,10774163 and 10974225)by National Fundamental Research Program of China (Grant No. 2006CB921203)
文摘This paper reports that a cloud of laser-cooled ^40Ca^＋ is successfully trapped and manipulated in the home-built linear ion trap constructed for quantum information processing （QIP）. The frequency of the secular motion and the space charge density of the ion cloud are measured, which help knowing the characteristic of the trapping potential and are the prerequisite of QIP with the trapped ions.
基金supported by National Natural Science Foundation of China(Nos.11075029,10975030)
文摘We present a model which is used to study ion transport in capacitively coupled plasma （CCP） discharge driven by a radio-frequency （rf） source for an etching process. The model combines a collisional sheath model with a trench model. The sheath model can calculate the ion energy distributions （IEDs） and ion angular distributions （IADs） to specify the initial conditions of the ions incident into the trench domain （a simulation area near and in the trench）. Then, considering the charging effect on the photoresist sidewalls and the rf-bias applied to the substrate, the electric potentials in the trench domain are computed by solving the Laplace equation. Finally, the trajectories, IEDs and IADs of ions impacting on the bottom of the trench are obtained using the trench model. Numerical results show that as the pressure increases, ions tend to strike the trench bottom with smaller impact energies and larger incident angles due to the collision processes, and the existence of the trench has distinct influences on the shape of the IEDs and IADs. In addition, as the bias amplitude increases, heights of both peaks decrease and the IEDs spread to a higher energy region.
文摘This paper presents analyses of ion flow characteristics and ion discharge pulses in a sphere-ground plate electrode system. As a result of variation in electric field intensity in the electrode gap, the ion flows towards electrodes generate non-uniform discharging pulses. Inspection of these pulses provides useful information on ionic stream kinetics, the effective thickness of ion cover around electrodes, and the timing of ion clouds discharge pulse sequences. A finite difference time domain （FDTD） based space-charge motion simulation is used for the numerical analysis of the spatio-temporal development of ionic flows following the first Townsend avalanche, and the simulation results demonstrate expansion of the positive ion flow and compression of the negative ion flow, which results in non-uniform discharge pulse characteristics.
