oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Simulation methods of ion sheath dynamics in plasma source ion implantation
Jiuli Wang,Guling Zhang,Younian Wang,Yuanfu Liu,Chizi Liu,Size Yang
Chinese Science Bulletin , 2004, DOI: 10.1007/BF02889743
Abstract: Progress of the theoretical studies on the ion sheath dynamics in plasma source ion implantation (PSII) is reviewed in this paper. Several models for simulating the ion sheath dynamics in PSII are provided. The main problem of nonuniform ion implantation on the target in PSII is discussed by analyzing some calculated results. In addition, based on the relative researches in our laboratory, some calculated results of the ion sheath dynamics in PSII for inner surface modification of a cylindrical bore are presented. Finally, new ideas and tendency for future researches on ion sheath dynamics in PSII are proposed.
Simulation methods of ion sheath dynamics in plasma source ion implantation
Jiuli Wang,Guling Zhang,Younian Wang,Yuanfu Liu,Chizi Liu,Size Yang,
WANGJiuli
,ZHANGGuling,WANGYounian,LIUYuanfu,LIUChizi,YANGSize

科学通报(英文版) , 2004,
Abstract: Progress of the theoretical studies on the ion sheath dynamics in plasma source ion implantation (PSII) is reviewed in this paper. Several models for simulating the ion sheath dynamics in PSII are provided. The main problem of nonuniform ion implantation on the target in PSII is dis-cussed by analyzing some calculated results. In addition, based on the relative researches in our laboratory, some cal-culated results of the ion sheath dynamics in PSII for inner surface modification of a cylindrical bore are presented. Fi-nally, new ideas and tendency for future researches on ion sheath dynamics in PSII are proposed.
Effect of Discharge Voltage on an Ion Sheath Formed at a Grid in a Multi-Dipole Discharge Plasma
M K Mishra,A Phukan,
M.
,K.,Mishra,A.,Phukan

中国物理快报 , 2008,
Abstract: It is experimentally demonstrated that a relatively strong ion-rich sheath formed at a fixed negative bias of the grid can be changed to a rather weak ion sheath (sheath potential weakly retards electrons) only by increasing the discharge voltage in the system. At sufficiently high negative grid bias, anincrease of discharge voltage enhances the ion collection current at the grid. An explanation is put forward in support of this experimental observation. A slight density enhancement with a fall in plasma electron temperature is also observed with the increasing negative grid bias.
ION HEATING PROCESS DURING PLASMA IMMERSION ION IMPLANTATION
XB Tian,XF Wang,AG Liu,LP Wang,S Y Wang,B Y Tang,P K Chu Advanced Welding Production & Technology National Key Laboratory,Harbin Institute of Technology,Harbin,China,

金属学报(英文版) , 2000,
Abstract: The research on plasma immersion ion implantation has been conducted for a little over ten years. Much is needed to investigate including processing technlogy, plasma sheath dynamics, interaction of plasma and surface, etc. Of the processing methods elavated temperature technique is usually used in PIII to produce a thick modified layer by means of the thermal diffusion. Meanwhile plasma ion heating is more recently developed by Ronghua Wei et al1]. Therefore the temeperature is a critical parameter in plasma ion processing. In this paper we present the theoretical model and analysize the effect of imlantation voltage, plasma density, ion mass,etc on the temperature rise.
Effects of charging at dielectric surfaces on the characteristics of the sheath for plasma immersion ion implantation
介质靶表面的充电效应对等离子体浸没离子注入过程中鞘层特性的影响

Li Xue-Chun,Wang You-Nian,
李雪春
,王友年

物理学报 , 2004,
Abstract: Using the one_dimensional dynamic sheath model, the effects of charging at a planar dielectric surface in plasma immersion ion implantation are studied. The temporal evolution of the sheath thickness, the effective potential at the surface of the dielectric and the ion dose accumulated on it are obtained for different plasma densities and dielectric thicknesses. The numerical results demonstrated that due to the charging effects, the plasma density has a profound impact on doping result during plasma immersion ion implantation, but the thickness of the dielectric has no significant effect on it.
Effect of rise-time patterns on dynamics of sheath expansion during plasma immersion ion implantation
脉冲偏压上升沿特性对等离子体浸没离子注入鞘层扩展动力学的影响

Huang Yong-Xian,Tian Xiu-Bo,Yang Shi-Qin,Fu Ricky,Chu KPaul,
黄永宪
,田修波,杨士勤,Fu Ricky,Chu K.Paul

物理学报 , 2007,
Abstract: Plasma immersion ion implantation (PIII) has been developed as a low_cost and efficient surface modification technique of irregularly-shaped objects. The effect of six pulse waves with different rise_time patterns on the spatio-temporal evolution of plasma sheath, energy and dose of ion implantation has been simulated by particle-in-cell modeling. Statistical results may be obtained through assuming the Boltzmann distribution of electrons, and solving Poisson and Newton equations for tracing each ion in the plasma sheath. The results show that rise_time pattern has a critical influence on the evolution of plasma sheath. There exists maximum thickness difference of plasma sheath for different waveforms. The acceleration of ions is non_uniform due to the non-uniformity of electrical field strength. The maximum gradient of electrical field appears near the edge of plasma sheath. The results also show that optimization of dose and energy of incident ions may be achieved through modification of rise_time pattern. The numerical simulation of sheath expansion can be effectively used to provide a scientific basis for optimizing the PIII process.
Behaviors of positively charged fine particles in a cross field sheath between magnetized double plasmas  [PDF]
Takuma Gohda,Satoru Iizuka
Physics , 2004,
Abstract: Dependencies of levitation position of positively charged fine-particles on plasma parameters are investigated. The charges on the particles become positive in a cross-field sheath between magnetized double plasmas with different potentials separated vertically by horizontal magnetic field, because ion current flowing from a lower high-potential plasma surpasses electron current coming across the magnetic field from an upper low-potential plasma. From measurement of the resonance frequency of the particles driven by external oscillating electric field, the charge on particle is estimated to be of the order of 10e2. Variation of particle levitation positions can be explained by the change of the charges.
Theory of the Electron Sheath and Presheath  [PDF]
Brett Scheiner,Scott D. Baalrud,Benjamin T. Yee,Matthew M. Hopkins,Edward V. Barnat
Physics , 2015,
Abstract: Electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in Particle-In-Cell (PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperature plasma conditions ($T_e\gg T_i$), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow is due to 2D aspects of the sheath geometry. Simulations also indicate the presence of ion acoustic waves excited by the differential flow between electrons and ions in the presheath which result in sheath edge fluctuations. The 1D model and time averaged PIC simulations are compared and it is shown that the model provides a good description of the electron sheath and presheath.
Transport of thermal plasma above the auroral ionosphere in the presence of electrostatic ion-cyclotron turbulence  [PDF]
V. E. Zakharov,C.-V. Meister
Annales Geophysicae (ANGEO) , 2003,
Abstract: The electron component of intensive electric currents flowing along the geomagnetic field lines excites turbulence in the thermal magnetospheric plasma. The protons are then scattered by the excited electromagnetic waves, and as a result the plasma is stable. As the electron and ion temperatures of the background plasma are approximately equal each other, here electrostatic ion-cyclotron (EIC) turbulence is considered. In the nonisothermal plasma the ion-acoustic turbulence may occur additionally. The anomalous resistivity of the plasma causes large-scale differences of the electrostatic potential along the magnetic field lines. The presence of these differences provides heating and acceleration of the thermal and energetic auroral plasma. The investigation of the energy and momentum balance of the plasma and waves in the turbulent region is performed numerically, taking the magnetospheric convection and thermal conductivity of the plasma into account. As shown for the quasi-steady state, EIC turbulence may provide differences of the electric potential of ΔV≈1–10 kV at altitudes of 500 < h < 10 000 km above the Earth's surface. In the turbulent region, the temperatures of the electrons and protons increase only a few times in comparison with the background values. Key words. Magnetospheric physics (electric fields; plasma waves and instabilities)
Behavior of test particles in the plasma sheath upon local bias and plasma switching  [PDF]
G. Schubert,R. Basner,H. Kersten,H. Fehske
Physics , 2010,
Abstract: Equilibrating gravitation by electric forces, microparticles can be confined in the plasma sheath above suitably biased local electrodes.Their position depends on the detailed structure of the plasma sheath and on the charge that the particles acquire in the surrounding plasma, that is by the electron and ion currents towards it. Bias switching experiments reveal how the charge and equilibrium position of the microparticle change upon altered sheath conditions. We observe similar particle behaviors also in the afterglow of the discharge for a persisting bias voltage on the electrode: damped oscillation into a new equilibrium or (accelerated) fall according to the bias.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.