等离子体基本特征I-美国某高校等离子体讲义系列.pptVIP

* EE 403/503 Introduction to Plasma Processing October 19, 2004 100 1020 1022 1024 108 1010 1012 1014 1016 1018 105 102 104 106 104 103 102 101 100 10-1 Average Electron Energy, [eV] Electron Number density, [cm-3] Thermonuclear Plasmas Electron Beam Glow Discharge Arc Discharge Solid MHD Generator Ionosphere Solar Corona Interstellar Gas Gaseous Nebulae Debye Length, ?D Link 1- Charge Neutrality 2- Plasma Sheaths 3- Shielded Coulomb Potential Plasma Frequency, ?p or ?P Plasma Response Time Two fundamental Plasma Parameters Debye Length Plasma Frequency [m] [sec-1] Debye Length [m] 100 1020 1022 1024 108 1010 1012 1014 1016 1018 105 102 104 106 104 103 102 101 100 10-1 Average Electron Energy, [eV] Electron Number density, [cm-3] Thermonuclear Plasmas Electron Beam Glow Discharge Arc Discharge Solid MHD Generator Ionosphere Solar Corona Interstellar Gas Gaseous Nebulae 1 cm 1 m 1 ?m 1 ? 1 nm 1 mm ?P = 100 Hz ?P = 10 KHz ?P = 1 MHz ?P = 100 MHz ?P = 10 GHz ?P = 1 THz Plasma Frequency Hz + + + + + + + + - - - - - - - - + + + + + + + + - - - - - - - - + + + + + + + + - - - - - - - - + + + + + + + + - - - - - - - - + + + + + + + + - - - - - - - + + + + + + + + - - - - - - - + + + + + + + + - - - - - - - + + + + + + + + - - - - - - - 0 0 y0 d y Ey y Ey + + + + + + + + - - - - - - - + + + + + + + + - - - - - - - + + + + + + + + - - - - - - - + + + + + + + + - - - - - - - 0 y0 d y Ey [m] The work necessary to move each electron an additional distance d is: Mean Thermal Energy Sheath Solid x 0 ?0 ?(x) Plasma ne=ni=n for x?D Sheath Solid x 0 ?0 ?(x) Plasma ne=ni=n for x?D Taylor Expansion: Approximate Solution q Sheath Plasma Particle r ?(x) ?(x1) ?x before after ne n+?n(x) x x1 Page 131 Assuming d