The microwave （MW） transmission method is employed to measure both the plasma density and the plasma decay time in the hollow cathode discharge （HCD） in argon at low pressure. The plasma density in DC-driven or pu...The microwave （MW） transmission method is employed to measure both the plasma density and the plasma decay time in the hollow cathode discharge （HCD） in argon at low pressure. The plasma density in DC-driven or pulsed HCD is on the order of 1012 cm-3, which can block the X-band MW effectively. In the case of pulsed HCD, the MW transmittance shows the same waveform as the pulsed current during the rising edge if the driving frequency is low, but with a longer delay during the falling edge. The MW transmittance reaches a constant low level when the driving frequency is high enough. The plasma decay time in the HCD system is measured to be about 100 μs around a pressure of 120 Pa. The ambipolar diffusion is considered to be the major mechanism in the decay process.展开更多
Computer to conventional plate （CTCP） technology is getting more and more attention in printing industries. In this paper we report a nitrogen plasma light source generated in hollow cathode discharge （HCD）, Which...Computer to conventional plate （CTCP） technology is getting more and more attention in printing industries. In this paper we report a nitrogen plasma light source generated in hollow cathode discharge （HCD）, Which is used for pre-sensitivity （PS） plate exposure. The N2 molecule emits abundant spectrum ranging from 350 nm to 460 nm. With the voltage of 580 V, current of 1.8 A and pressure of 70 Pa in the discharge an optical power density of 0.46 mW/cm2 is obtained. The optical power density could be further increased with optimizing the lens system. The phototonus efficiency of this source is discussed in detail based upon the chemical principle and the FTIR analysis on the coating material.展开更多
The mechanism of micro-hollow cathode discharge at atmospheric pressure is investigated through simulations using two-dimensional fluid model combined with a transport model for metastable atoms.In the simulations,ele...The mechanism of micro-hollow cathode discharge at atmospheric pressure is investigated through simulations using two-dimensional fluid model combined with a transport model for metastable atoms.In the simulations,electric potential,electric field,particle density,and mean electron energy of the discharge are calculated.The results show that the two characteristic regions of the discharge,i.e.cathode drop and negative glow can be distinguished in the simulation.The cathode drop is characterized by strong electric field and high mean electron energy,while quasi-neutral plasma of high density and exists in the negative glow.The peak value of electron density can reach the order of 1017cm-3.The electron temperature varies from several eV to tens of eV.The influence of cathode dimension on the discharge characteristics is also investigated.展开更多
A large plasma sheet 60 cm×60 cm×2 cm in size was generated using a hollow cathode, and measurements were conducted for interactions including transmission, reflection and absorption. With different discharg...A large plasma sheet 60 cm×60 cm×2 cm in size was generated using a hollow cathode, and measurements were conducted for interactions including transmission, reflection and absorption. With different discharge parameters, plasma sheets can vary and influence microwave strength. Microwave reflection decreases when the discharge current rises, and the opposite occurs in transmission. The C-band microwave is absorbed when it is propagated through large plasma sheets at higher pressure. When plasma density and collision frequency are fitted with incident microwave frequency, a large amount of microwave energy is consumed. Reflection, transmission and absorption all exist simultaneously. Plasma sheets are an attractive alternative to microwave steering at low pressure, and the microwave reflection used in receiving radar can be altered by changing the discharge parameters.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.11005009)
文摘The microwave （MW） transmission method is employed to measure both the plasma density and the plasma decay time in the hollow cathode discharge （HCD） in argon at low pressure. The plasma density in DC-driven or pulsed HCD is on the order of 1012 cm-3, which can block the X-band MW effectively. In the case of pulsed HCD, the MW transmittance shows the same waveform as the pulsed current during the rising edge if the driving frequency is low, but with a longer delay during the falling edge. The MW transmittance reaches a constant low level when the driving frequency is high enough. The plasma decay time in the HCD system is measured to be about 100 μs around a pressure of 120 Pa. The ambipolar diffusion is considered to be the major mechanism in the decay process.
基金the scientific research common program of Beijing municipal commission(No.KM200710015002)the Beijing elitist funds (No.20051D0500403)
文摘Computer to conventional plate （CTCP） technology is getting more and more attention in printing industries. In this paper we report a nitrogen plasma light source generated in hollow cathode discharge （HCD）, Which is used for pre-sensitivity （PS） plate exposure. The N2 molecule emits abundant spectrum ranging from 350 nm to 460 nm. With the voltage of 580 V, current of 1.8 A and pressure of 70 Pa in the discharge an optical power density of 0.46 mW/cm2 is obtained. The optical power density could be further increased with optimizing the lens system. The phototonus efficiency of this source is discussed in detail based upon the chemical principle and the FTIR analysis on the coating material.
基金Project supported by National Science Foundation of China （11205046, 51077035）, Science Foundation of Hebei Province（A2012201037）, China Postdoctoral Science Foundation（2013M541195）, Science Foundation of Hebei University （2011YYO 1, 2012-237）.
文摘The mechanism of micro-hollow cathode discharge at atmospheric pressure is investigated through simulations using two-dimensional fluid model combined with a transport model for metastable atoms.In the simulations,electric potential,electric field,particle density,and mean electron energy of the discharge are calculated.The results show that the two characteristic regions of the discharge,i.e.cathode drop and negative glow can be distinguished in the simulation.The cathode drop is characterized by strong electric field and high mean electron energy,while quasi-neutral plasma of high density and exists in the negative glow.The peak value of electron density can reach the order of 1017cm-3.The electron temperature varies from several eV to tens of eV.The influence of cathode dimension on the discharge characteristics is also investigated.
文摘A large plasma sheet 60 cm×60 cm×2 cm in size was generated using a hollow cathode, and measurements were conducted for interactions including transmission, reflection and absorption. With different discharge parameters, plasma sheets can vary and influence microwave strength. Microwave reflection decreases when the discharge current rises, and the opposite occurs in transmission. The C-band microwave is absorbed when it is propagated through large plasma sheets at higher pressure. When plasma density and collision frequency are fitted with incident microwave frequency, a large amount of microwave energy is consumed. Reflection, transmission and absorption all exist simultaneously. Plasma sheets are an attractive alternative to microwave steering at low pressure, and the microwave reflection used in receiving radar can be altered by changing the discharge parameters.
