Abstract In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device ...Abstract In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device is introduced, and the distribution of mirror magnetic field generated by the loops surrounding the discharge chamber is presented. Both the discharge current-voltage characteristics and the radial distributions of electron density are measured, respectively, with/without the magnetic field. When the discharge occurs in a 99.99% helium with a pressure ranging from 100 Pa to 800 Pa without magnetic field, the voltage, sustaining a certain abnormal glow discharge current, decreases with the increase in gas pressure. With a mirror magnetic field of certain intensity, the discharge voltage increases with the current in a rate slower than that without the magnetic field. Moreover, when the magnetic field intensity increases, the discharge voltage first decreases then increases. Simultaneously, the mirror magnetic field affects the moving characteristics of charged particles, and causes a more inhomogeneous electron density.展开更多
A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform ele...A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform electric field in a positive column of helium direct current(DC) gas discharge Graphs showing the electron density and energy distributions, and the percentage of electrons that reach the wall and the end of the positive column are presented. The results indicate that the mirror magnetic field can control the electron transport behavior in the positive column which are in good agreement with experimental results.展开更多
The magnetic mirror field caused by a pair of mild steel circular in 15mm diameter, 2 mm thickness placed outside the discharge chamber can increase the atom ion ratio of nitrogen from 66% to 81 %, and the heating fil...The magnetic mirror field caused by a pair of mild steel circular in 15mm diameter, 2 mm thickness placed outside the discharge chamber can increase the atom ion ratio of nitrogen from 66% to 81 %, and the heating filament current can be decreased from 130 A down to 100 A for a new filament of 2 mm in diameter. The Mo shield cylinders in 14mm diameter put behind the reflect cathode surrounding the BN insulator prevent the metallization of BN insulators, and result in increasing the stability of arc discharge till to the end of filament working life. Because it restricts the deposition of the sputtered W and Mo atoms on the BN insulator, and maintains a high resistance of 70 Mad between the anode and cathode. The combination of cathode shield cylinder and forming magnetic mirror field improves the running property, life of the Freeman source being about 40 h.展开更多
A triode extraction system is designed for a dual hollow cathode ion source being developed at the Institute of Heavy Ion Physics, Peking University. Basic parameters of the plasma are selected after examining the ope...A triode extraction system is designed for a dual hollow cathode ion source being developed at the Institute of Heavy Ion Physics, Peking University. Basic parameters of the plasma are selected after examining the operation principle of the ion source, then the triode extraction system is designed and optimized by using software PBGUNS （for Particle Beam GUN Simulations）. The physical design of the system is given in this paper.展开更多
基金Program for New Century Excellent Talents in University (NCET) of ChinaFundation of the Key Lab of Infrared and Low Temperature Plasma of Anhui Province of China(No.2007A003003U)
文摘Abstract In the four-anode device, the mirror magnetic field affects the characteristics of charged particles motion, so that the current-voltage relations of glow discharge are changed. Firstly, the discharge device is introduced, and the distribution of mirror magnetic field generated by the loops surrounding the discharge chamber is presented. Both the discharge current-voltage characteristics and the radial distributions of electron density are measured, respectively, with/without the magnetic field. When the discharge occurs in a 99.99% helium with a pressure ranging from 100 Pa to 800 Pa without magnetic field, the voltage, sustaining a certain abnormal glow discharge current, decreases with the increase in gas pressure. With a mirror magnetic field of certain intensity, the discharge voltage increases with the current in a rate slower than that without the magnetic field. Moreover, when the magnetic field intensity increases, the discharge voltage first decreases then increases. Simultaneously, the mirror magnetic field affects the moving characteristics of charged particles, and causes a more inhomogeneous electron density.
文摘A Monte Carlo simulation technique has been used to model the electron transport' behavior, especially the electron density and energy distributions under the influence of a mirror magnetic field and a uniform electric field in a positive column of helium direct current(DC) gas discharge Graphs showing the electron density and energy distributions, and the percentage of electrons that reach the wall and the end of the positive column are presented. The results indicate that the mirror magnetic field can control the electron transport behavior in the positive column which are in good agreement with experimental results.
文摘The magnetic mirror field caused by a pair of mild steel circular in 15mm diameter, 2 mm thickness placed outside the discharge chamber can increase the atom ion ratio of nitrogen from 66% to 81 %, and the heating filament current can be decreased from 130 A down to 100 A for a new filament of 2 mm in diameter. The Mo shield cylinders in 14mm diameter put behind the reflect cathode surrounding the BN insulator prevent the metallization of BN insulators, and result in increasing the stability of arc discharge till to the end of filament working life. Because it restricts the deposition of the sputtered W and Mo atoms on the BN insulator, and maintains a high resistance of 70 Mad between the anode and cathode. The combination of cathode shield cylinder and forming magnetic mirror field improves the running property, life of the Freeman source being about 40 h.
基金Supported by National Natural Science Foundation of China (10775011)
文摘A triode extraction system is designed for a dual hollow cathode ion source being developed at the Institute of Heavy Ion Physics, Peking University. Basic parameters of the plasma are selected after examining the operation principle of the ion source, then the triode extraction system is designed and optimized by using software PBGUNS （for Particle Beam GUN Simulations）. The physical design of the system is given in this paper.
