第1章 等离子体基本知识
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2 1 P = mnV 3
n——the number density v ——root mean square velocity of the molecular m —— molecular mass
Mixture: P = P1+P2 + P3 + P4 +……
2.4 Mean free path (平均自由程）
2.2 Definition of Velocities: Most probable velocity(最可几速率）
Average velocity:
Root mean square (rms) velocity (均方根速率）
Kinetic energy of a molecular
Mean velocities of some gas at 16℃
等离子体是物质第四态
固体 冰 液体 水 气体
水汽
等离子体
电离气体
0 0C
1000C
100000C 温度
电离气体是一种常见的等离子体
普通气体
等离子体
放电 放电是使气体转变成等离子体的一种常见形式
等离子体 ≈ 电离气体
1.2 粒子的种类
Molecule the smallest unit of matter that can exist by itself and retain all its chemical properties. In a molecule a group of atoms are held together by chemical forces. Atom previously understood as indivisible piece of matter first postulated by the Greeks, but known to be composed of nucleus circled by electrons. Nucleus a heavy positively charged center of the atom, composed of protons and neutrons. More than 100 types of nuclear particle have been discovered up to now.
P ~ 10-6 Torr P ~ 10-10 Torr
3. 等离子体
3.1 等离子体形成过程 Collision： Collision： Reaction Cross Section
Excitation and Ionization
Excitation Excitation Excitation Excitation and and and and ionization ionization ionization ionization by by by by an electron impact： impact： an ion collision： collision： a neutral particle collision： collision： radiation： radiation：
特征响应时间：τp＝ λD/vT＝1/ωp
－
屏蔽层厚度：德拜长度 λD
在等离子体中引入带负电荷的薄层 ，经过一定的时间， 等离子体中的电子、离子将移动，屏蔽电场——德拜屏蔽 等离子体中的电子、离子将移动，屏蔽电场——德拜屏蔽
λ De
εTe = en 0
1/ 2
当Te = 4V和ne = 1010 cm-3时，德拜 长度=0.14mm
Gas H2 He H2O 565 N2 454 O2 425 Ar 380 CO 454 CO2 362 Hg 170
Velocity(m/s) 1693 1பைடு நூலகம்08
2.3 Pressure
Definition: Effect of collisions between the molecular and the wall
2.6 The monolayer arrival time ，τ
If N0 is the number of atoms in a monolayer (the ML unit) then Rτ = N0
Gas Density, Degree of Vacuum Atmospher ic Low Medium High UltraHigh Pressure (Torr) ρ (molecules m-3 ) 2 x 1025 3 x 1022 3 x 1019 3 x 1016 3 x 1012
Mean Free Path (m) 7 x 10-8 5 x 10-5 5 x 10-2 50 5 x 105
Time / ML, tML (s) 10-9 10-6 10-3 1 104
760 1 10-3 10-6 10-10
Collision Free Conditions: Maintain a Clean Surface:
3.2 等离子体参数
3.2.1 The mean kinetic energy
3 1 2 ε = kT = mvrs 2 2
vrs is root mean square velocity m - mass of the particle T - absolute temperature k is Boltzmann constant.
第一章 等离子体
内 容
基本概念 气体分子运动理论 等离子体参数 等离子体形成方法
1. 基本概念
1.1 物质的几种基本状态 Solids: Solids: Matters consisting of molecules and atoms with very high levels of arrangement Mobility of atoms and molecules is very limited. limited. Liquids: Liquids: Matters consisting of atoms or molecules with closed arrangements, There may exist crystalline arrangements of particles in small complexes within a range of nm Characterized with easiness of mobility.
3.2.5 3.2. 准电中性
在等离子体内部，正、负电荷数几乎相等——准中性 在等离子体内部，正、负电荷数几乎相等——准中性
n e ≈ ni
3.2.6 3.2.6 等离子体振荡
在无外加驱动场的条件下，一个平板形等离子体 会发生振荡
Ex =
en0ξ e
d 2ξ e m 2 = −eE x dt
ε0
ne = n1 + n2 + ... + ni + ... + nn = ∑ ni = n
i =1 n
3.2.4 3.2. Debye length
德拜( 德拜( Debye )屏蔽 )屏蔽
－
在等离子体中引入带负电荷的薄层 在等离子体中引入带负电荷的薄层 ，经过一定的 时间…….. 时间……..
德拜( 德拜( Debye )屏蔽 )屏蔽
Schematic of the motion of the molecular
Molecular: Ion: Electron:
λ=
kT 2πd 2 P
T=25 ℃
5 × 10 λ ≈ P
−3
( cm )
λi = 2λ
Because of large speed
Because of large speed and small diameter
ω pe
e n0 = ε m 0
2
1/ 2
3.2.7 3.2.7 等离子体参数空间 温度 (度)
Gases: Gases: Systems of atoms or molecules behaving as free entities. The matters in the gaseous phase at the normal conditions are called gases. gases. Other matters passing into the gaseous phase by increasing temperature or pressure drop are called vapors. vapors. Plasma: Plasma: A physical system consisting of neutrals, molecules, atoms, excited particles, ions, electrons and electromagnetic radiation.
λe = 4 2λ
Mean free path at different pressures
2.5 Arrival rate of atoms at a Surface
This arrival rate R, or Flux F, R or F = nv/4 The molecular density n, n = p/kT The mean speed of the molecules ， v = (8kT/πm)1/2
3.2.2 Temperature of plasma
The electron temperature Te, The ion temperature Ti, The gas temperature Tg.
3.2.3 Plasma Density Plasma is a collection of particles consisting of electrons, ions and excited particles Electron density of ne, is known as the plasma density.
Recombination
IonIon-Electron Recombination：A+ + e → A* + hv Recombination： Ion – Ion Recombination：A+ + B- →AB + hv Recombination： Attachment and detachment：M(g) + e→M-(g) detachment：
Electron a small negatively charged particle that normally circles the nucleus of an atom. Proton massive positively charged particle that is the nucleus of the hydrogen atom. Neutron a particle of approximately the same mass as proton, but uncharged. Outside the nucleus a neutron can not exist alone; It is unstable and will decay into proton and an electron. Ion an atom or molecule that by loss or gain of one or more electrons has acquired a net charge. Loss of electrons results in a positive ion, gain of electron results in a negative ion. ion, ion.
2. 气体分子运动理论
2.1 Maxwellian distribution
Random velocity of electron or gas molecules is described by Maxwellian distribution when the system is at thermal equilibrium.
n——the number density v ——root mean square velocity of the molecular m —— molecular mass
Mixture: P = P1+P2 + P3 + P4 +……
2.4 Mean free path (平均自由程）
2.2 Definition of Velocities: Most probable velocity(最可几速率）
Average velocity:
Root mean square (rms) velocity (均方根速率）
Kinetic energy of a molecular
Mean velocities of some gas at 16℃
等离子体是物质第四态
固体 冰 液体 水 气体
水汽
等离子体
电离气体
0 0C
1000C
100000C 温度
电离气体是一种常见的等离子体
普通气体
等离子体
放电 放电是使气体转变成等离子体的一种常见形式
等离子体 ≈ 电离气体
1.2 粒子的种类
Molecule the smallest unit of matter that can exist by itself and retain all its chemical properties. In a molecule a group of atoms are held together by chemical forces. Atom previously understood as indivisible piece of matter first postulated by the Greeks, but known to be composed of nucleus circled by electrons. Nucleus a heavy positively charged center of the atom, composed of protons and neutrons. More than 100 types of nuclear particle have been discovered up to now.
P ~ 10-6 Torr P ~ 10-10 Torr
3. 等离子体
3.1 等离子体形成过程 Collision： Collision： Reaction Cross Section
Excitation and Ionization
Excitation Excitation Excitation Excitation and and and and ionization ionization ionization ionization by by by by an electron impact： impact： an ion collision： collision： a neutral particle collision： collision： radiation： radiation：
特征响应时间：τp＝ λD/vT＝1/ωp
－
屏蔽层厚度：德拜长度 λD
在等离子体中引入带负电荷的薄层 ，经过一定的时间， 等离子体中的电子、离子将移动，屏蔽电场——德拜屏蔽 等离子体中的电子、离子将移动，屏蔽电场——德拜屏蔽
λ De
εTe = en 0
1/ 2
当Te = 4V和ne = 1010 cm-3时，德拜 长度=0.14mm
Gas H2 He H2O 565 N2 454 O2 425 Ar 380 CO 454 CO2 362 Hg 170
Velocity(m/s) 1693 1பைடு நூலகம்08
2.3 Pressure
Definition: Effect of collisions between the molecular and the wall
2.6 The monolayer arrival time ，τ
If N0 is the number of atoms in a monolayer (the ML unit) then Rτ = N0
Gas Density, Degree of Vacuum Atmospher ic Low Medium High UltraHigh Pressure (Torr) ρ (molecules m-3 ) 2 x 1025 3 x 1022 3 x 1019 3 x 1016 3 x 1012
Mean Free Path (m) 7 x 10-8 5 x 10-5 5 x 10-2 50 5 x 105
Time / ML, tML (s) 10-9 10-6 10-3 1 104
760 1 10-3 10-6 10-10
Collision Free Conditions: Maintain a Clean Surface:
3.2 等离子体参数
3.2.1 The mean kinetic energy
3 1 2 ε = kT = mvrs 2 2
vrs is root mean square velocity m - mass of the particle T - absolute temperature k is Boltzmann constant.
第一章 等离子体
内 容
基本概念 气体分子运动理论 等离子体参数 等离子体形成方法
1. 基本概念
1.1 物质的几种基本状态 Solids: Solids: Matters consisting of molecules and atoms with very high levels of arrangement Mobility of atoms and molecules is very limited. limited. Liquids: Liquids: Matters consisting of atoms or molecules with closed arrangements, There may exist crystalline arrangements of particles in small complexes within a range of nm Characterized with easiness of mobility.
3.2.5 3.2. 准电中性
在等离子体内部，正、负电荷数几乎相等——准中性 在等离子体内部，正、负电荷数几乎相等——准中性
n e ≈ ni
3.2.6 3.2.6 等离子体振荡
在无外加驱动场的条件下，一个平板形等离子体 会发生振荡
Ex =
en0ξ e
d 2ξ e m 2 = −eE x dt
ε0
ne = n1 + n2 + ... + ni + ... + nn = ∑ ni = n
i =1 n
3.2.4 3.2. Debye length
德拜( 德拜( Debye )屏蔽 )屏蔽
－
在等离子体中引入带负电荷的薄层 在等离子体中引入带负电荷的薄层 ，经过一定的 时间…….. 时间……..
德拜( 德拜( Debye )屏蔽 )屏蔽
Schematic of the motion of the molecular
Molecular: Ion: Electron:
λ=
kT 2πd 2 P
T=25 ℃
5 × 10 λ ≈ P
−3
( cm )
λi = 2λ
Because of large speed
Because of large speed and small diameter
ω pe
e n0 = ε m 0
2
1/ 2
3.2.7 3.2.7 等离子体参数空间 温度 (度)
Gases: Gases: Systems of atoms or molecules behaving as free entities. The matters in the gaseous phase at the normal conditions are called gases. gases. Other matters passing into the gaseous phase by increasing temperature or pressure drop are called vapors. vapors. Plasma: Plasma: A physical system consisting of neutrals, molecules, atoms, excited particles, ions, electrons and electromagnetic radiation.
λe = 4 2λ
Mean free path at different pressures
2.5 Arrival rate of atoms at a Surface
This arrival rate R, or Flux F, R or F = nv/4 The molecular density n, n = p/kT The mean speed of the molecules ， v = (8kT/πm)1/2
3.2.2 Temperature of plasma
The electron temperature Te, The ion temperature Ti, The gas temperature Tg.
3.2.3 Plasma Density Plasma is a collection of particles consisting of electrons, ions and excited particles Electron density of ne, is known as the plasma density.
Recombination
IonIon-Electron Recombination：A+ + e → A* + hv Recombination： Ion – Ion Recombination：A+ + B- →AB + hv Recombination： Attachment and detachment：M(g) + e→M-(g) detachment：
Electron a small negatively charged particle that normally circles the nucleus of an atom. Proton massive positively charged particle that is the nucleus of the hydrogen atom. Neutron a particle of approximately the same mass as proton, but uncharged. Outside the nucleus a neutron can not exist alone; It is unstable and will decay into proton and an electron. Ion an atom or molecule that by loss or gain of one or more electrons has acquired a net charge. Loss of electrons results in a positive ion, gain of electron results in a negative ion. ion, ion.
2. 气体分子运动理论
2.1 Maxwellian distribution
Random velocity of electron or gas molecules is described by Maxwellian distribution when the system is at thermal equilibrium.