A compact mirror-like ECR (electron cyclotron resonance) Plasma source for the ionosphere environment simulator was described for the fort time in China. The Overall sources system was composed of a 200 W 2.45 GHz mic...A compact mirror-like ECR (electron cyclotron resonance) Plasma source for the ionosphere environment simulator was described for the fort time in China. The Overall sources system was composed of a 200 W 2.45 GHz microwave source, a coastal 3A./4 TEM-mode microwave resonance applicator, column and cylindrical Nd-Fe-P magnets, a quartz bell-shaped discharge chamber, a gas inlet system and a plasma-diffusing bore. The preliminary experiment demonstrated that ambi-polar diffusion plasma stream into the simulator (-500 mm long) formed an environment with following parameters: a plasma density ne of 104 cm-3 - 106 cm-3, an electron temperature Te < 5 eV at a pressure P of 10-1 Pa-10-3 Pa, a Plasma uniformity of > 80% over the experimental target with a 160-mm-in-diameter, satisfying primarily the requirement of simulating in a severe ionosphere environment.展开更多
Using a Monte Carlo method and resonable data in our experiment device, we simulate the plasma stream of ECR plasma source on condition that the plasma is collisionless. We can get the distribution of ion density and ...Using a Monte Carlo method and resonable data in our experiment device, we simulate the plasma stream of ECR plasma source on condition that the plasma is collisionless. We can get the distribution of ion density and the effect of magnetic field on the plasma along the divergent magnetic field. The research is beneficial to plasma processing applications.展开更多
In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600...In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600 W was launched into the circular cavity to generate ECR (electron cyclotron resonance) plasma. The oxygen ion beam moved onto a negatively biased Mo plate under the condition of symmetry magnetic mirror field confine, then was neutralized and reflected to form oxygen atom beam. The properties of plasma density, electron temperature, plasma space potential and ion incident energy were characterized. The atomic oxygen beam flux was calibrated by measuring the mass loss rate of Kapton during the atomic oxygen exposure. The test results show that the atomic oxygen beam with flux of 1016-1017 atoms-cm-2·s-1 and energy of 5-30 eV and a cross section of φ80 mm could be obtained under the operating pressure of 10-1-10-3 Pa. Such a high flux source can provide accelerated simulation tests of materials and coatings for space applications.展开更多
It is known that ion channel can effectively limit the radial expansion of an artificial electron beam during its longrange propagation in the space plasma environment.Most prior studies discussed the focusing charact...It is known that ion channel can effectively limit the radial expansion of an artificial electron beam during its longrange propagation in the space plasma environment.Most prior studies discussed the focusing characteristics of the beam in the ion channel,but the establishment process and transient properties of the ion channel itself,which also plays a crucial role during the propagation of the relativistic electron beam in the plasma environment,were commonly neglected.In this study,a series of two-dimensional(2D)particle-in-cell simulations is performed and an analytical model of ion channel oscillation is constructed according to the single-particle motion.The results showed that when the beam density is higher than the density of plasma environment,ion channel can be established and always continues to oscillate periodically over the entire propagation.Multiple factors,including the beam electron density,initial beam radius,and the plasma density can affect the oscillation properties of ion channel.Axial velocity of the beam oscillates synchronously with the ion channel and this phenomenon will finally develop into a two-stream instability which can seriously affect the effective transport for relativistic electron beam.Choosing appropriate beam parameters based on various plasma environments may contribute to the improvement of the stability of ion channel.Additionally,radial expansion of the beam can be limited by ion channel and a stable long-range propagation in terrestrial atmosphere may be achieved.展开更多
An atomic-oxygen beam source with compact ECR plasma was successfully investigated. The microwave was produced and transmitted in a coaxial mode, and coupled with the loop. The plasma was produced at a higher asymmetr...An atomic-oxygen beam source with compact ECR plasma was successfully investigated. The microwave was produced and transmitted in a coaxial mode, and coupled with the loop. The plasma was produced at a higher asymmetry magnetic mirror field, and neutralized with the molybdenum target at a lower asymmetry magnetic mirror field. The magnetic field was constituted with permanent magnets. This source has a higher flux density of atom beam, a lower operating pressure, a smaller power consumption and low-cost. When it was installed at the equipment to study the interaction of the beam with the surface, the operation was carried out very easily and with a good stability.展开更多
Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adeq...Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance（ECR） system for the ‘whistler/chorus＇ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén＇ wave study. The parameters of ‘whistler/chorus＇ waves and ‘Alfvén＇ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt＇ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.展开更多
The helicon plasma source,which generates high thrust and high impulse,is of vital importance for magnetoplasma rocket engines.In this work,a multi-component,two-dimensional,axisymmetric fluid model coupled with an el...The helicon plasma source,which generates high thrust and high impulse,is of vital importance for magnetoplasma rocket engines.In this work,a multi-component,two-dimensional,axisymmetric fluid model coupled with an electromagnetic field was developed to model the helicon discharge.The simulation results demonstrate that:(i)the discharge mode changes twice—each conversion is accompanied by a plasma density jump and an electron temperature peak in the discharge;(ii)when the input current increases,the plasma density increases,and ionization occurs faster;(iii)the background magnetic field clearly enhances the discharge;(iv)the plasma density may be smaller if the discharge has not entered the wave mode.展开更多
Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion sour...Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.展开更多
A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source, which has the ability of producing a tens-m A H＋beam, has been built and tested at Peking University（PKU）. Its plasma chamb...A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source, which has the ability of producing a tens-m A H＋beam, has been built and tested at Peking University（PKU）. Its plasma chamber dimension is Φ30 mm×40 mm and the whole size of the ion source is Φ180 mm×130 mm. This source has a unique structure with the whole source body embedded into the extraction system. It can be operated in both continuous wave（CW） mode and pulse mode. In the CW mode, more than 20 m A hydrogen ion beam at 40 k V can be obtained with the microwave power of 180 W and about 1 m A hydrogen ion beam is produced with a microwave power of 10 W. In the pulse mode, more than50 m A hydrogen ion beam with a duty factor of 10% can be extracted when the peak microwave power is 1800 W.展开更多
An electron cyclotron resonance ion source model that uses a coaxial antenna to inject the RF power was simulated, and the corresponding hydrogen plasma densities of the ion source were calculated at different magneti...An electron cyclotron resonance ion source model that uses a coaxial antenna to inject the RF power was simulated, and the corresponding hydrogen plasma densities of the ion source were calculated at different magnetic field distributions via a fluid model. The results show that most of the microwave power is absorbed around the resonance surface near the antenna when the plasma density is below the cutoff density of 7.4 × 10^(16) m^(-3) for 2.45 GHz microwaves, and the simulation results also show that the plasma density is strongly influenced by the position and shape of the resonance surface, where a larger resonance surface would improve the plasma density.展开更多
As clearly demonstrated at several laboratories,the performances of electron-cyclotron resonance (ECR)ion sources can be enhanced by increasing the physical sizes(volumes)of embedded ECR zones.En- larged ECR zones hav...As clearly demonstrated at several laboratories,the performances of electron-cyclotron resonance (ECR)ion sources can be enhanced by increasing the physical sizes(volumes)of embedded ECR zones.En- larged ECR zones have been achieved by engineering the central magnetic field region of these sources so they are uniformly-distributed"volumes"in resonance with single-frequency rf power.Alternatively,the number of ECR surfaces in conventional minimum-B geometry sources can be increased by heating their plasmas with multiple,discrete frequency microwave radiation.Broadband rf power offers a simple,low cost and arguably more effective means for increasing the physical sizes of the ECR zones within the latter source type.In this article,theoretical arguments are made in support of the volume effect and the charge-state enhancing ef- fects of broadband microwave radiation(bandwidth:200MHz)plasma heating are demonstrated by comparing the high-charge-states of Ar ion beams,produced by powering a conventional minimum-B geometry,6.4GHz ECR ion source,equipped with a biased disk,with those produced by conventional bandwidth(bandwidth:～1.5MHz)radiation.展开更多
文摘A compact mirror-like ECR (electron cyclotron resonance) Plasma source for the ionosphere environment simulator was described for the fort time in China. The Overall sources system was composed of a 200 W 2.45 GHz microwave source, a coastal 3A./4 TEM-mode microwave resonance applicator, column and cylindrical Nd-Fe-P magnets, a quartz bell-shaped discharge chamber, a gas inlet system and a plasma-diffusing bore. The preliminary experiment demonstrated that ambi-polar diffusion plasma stream into the simulator (-500 mm long) formed an environment with following parameters: a plasma density ne of 104 cm-3 - 106 cm-3, an electron temperature Te < 5 eV at a pressure P of 10-1 Pa-10-3 Pa, a Plasma uniformity of > 80% over the experimental target with a 160-mm-in-diameter, satisfying primarily the requirement of simulating in a severe ionosphere environment.
文摘Using a Monte Carlo method and resonable data in our experiment device, we simulate the plasma stream of ECR plasma source on condition that the plasma is collisionless. We can get the distribution of ion density and the effect of magnetic field on the plasma along the divergent magnetic field. The research is beneficial to plasma processing applications.
基金This work was supported by the National Key Basic Research and.Development Program of China(No.G19990650).
文摘In order to study the atomic oxygen corrosion of spacecraft materials in low earth orbit environment, an atomic oxygen simulator was established. In the simulator, a 2.45 GHz microwave source with maximum power of 600 W was launched into the circular cavity to generate ECR (electron cyclotron resonance) plasma. The oxygen ion beam moved onto a negatively biased Mo plate under the condition of symmetry magnetic mirror field confine, then was neutralized and reflected to form oxygen atom beam. The properties of plasma density, electron temperature, plasma space potential and ion incident energy were characterized. The atomic oxygen beam flux was calibrated by measuring the mass loss rate of Kapton during the atomic oxygen exposure. The test results show that the atomic oxygen beam with flux of 1016-1017 atoms-cm-2·s-1 and energy of 5-30 eV and a cross section of φ80 mm could be obtained under the operating pressure of 10-1-10-3 Pa. Such a high flux source can provide accelerated simulation tests of materials and coatings for space applications.
基金supported by the Joint Funds of the National Natural Science Foundation of China(Grant Nos.61372050 and U1730247).
文摘It is known that ion channel can effectively limit the radial expansion of an artificial electron beam during its longrange propagation in the space plasma environment.Most prior studies discussed the focusing characteristics of the beam in the ion channel,but the establishment process and transient properties of the ion channel itself,which also plays a crucial role during the propagation of the relativistic electron beam in the plasma environment,were commonly neglected.In this study,a series of two-dimensional(2D)particle-in-cell simulations is performed and an analytical model of ion channel oscillation is constructed according to the single-particle motion.The results showed that when the beam density is higher than the density of plasma environment,ion channel can be established and always continues to oscillate periodically over the entire propagation.Multiple factors,including the beam electron density,initial beam radius,and the plasma density can affect the oscillation properties of ion channel.Axial velocity of the beam oscillates synchronously with the ion channel and this phenomenon will finally develop into a two-stream instability which can seriously affect the effective transport for relativistic electron beam.Choosing appropriate beam parameters based on various plasma environments may contribute to the improvement of the stability of ion channel.Additionally,radial expansion of the beam can be limited by ion channel and a stable long-range propagation in terrestrial atmosphere may be achieved.
基金This work was supported by the National Natural Science Foundation of China No.19835030.
文摘An atomic-oxygen beam source with compact ECR plasma was successfully investigated. The microwave was produced and transmitted in a coaxial mode, and coupled with the loop. The plasma was produced at a higher asymmetry magnetic mirror field, and neutralized with the molybdenum target at a lower asymmetry magnetic mirror field. The magnetic field was constituted with permanent magnets. This source has a higher flux density of atom beam, a lower operating pressure, a smaller power consumption and low-cost. When it was installed at the equipment to study the interaction of the beam with the surface, the operation was carried out very easily and with a good stability.
基金supported by National Natural Science Foundation of China(Nos.11505040,11261140326,11405038 and 51577043)China Postdoctoral Science Foundation(Nos.2016M591518,2015M570283)HIT.NSRIF under Grant No.2017008
文摘Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance（ECR） system for the ‘whistler/chorus＇ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén＇ wave study. The parameters of ‘whistler/chorus＇ waves and ‘Alfvén＇ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt＇ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.
基金supported by the Shaanxi Key Laboratory of Plasma Physics and Applied Technology。
文摘The helicon plasma source,which generates high thrust and high impulse,is of vital importance for magnetoplasma rocket engines.In this work,a multi-component,two-dimensional,axisymmetric fluid model coupled with an electromagnetic field was developed to model the helicon discharge.The simulation results demonstrate that:(i)the discharge mode changes twice—each conversion is accompanied by a plasma density jump and an electron temperature peak in the discharge;(ii)when the input current increases,the plasma density increases,and ionization occurs faster;(iii)the background magnetic field clearly enhances the discharge;(iv)the plasma density may be smaller if the discharge has not entered the wave mode.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11175009 and 11575013)
文摘Optical emission spectroscopy（OES）, as a simple in situ method without disturbing the plasma, has been performed for the plasma diagnosis of a 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source at Peking University（PKU）. A spectrum measurement platform has been set up with the quartz-chamber electron cyclotron resonance（ECR） ion source [Patent Number： ZL 201110026605.4] and experiments were carried out recently. The electron temperature and electron density inside the ECR plasma chamber have been measured with the method of line intensity ratio of noble gas. Hydrogen plasma processes inside the discharge chamber are discussed based on the diagnostic results. What is more, the superiority of the method of line intensity ratio of noble gas is indicated with a comparison to line intensity ratio of hydrogen. Details will be presented in this paper.
基金Project supported by the National Basic Research Program of China(Grant No.2014CB845502)the National Natural Science Foundation of China(Grant No.11575013)
文摘A miniaturized 2.45 GHz permanent magnet electron cyclotron resonance（PMECR） ion source, which has the ability of producing a tens-m A H＋beam, has been built and tested at Peking University（PKU）. Its plasma chamber dimension is Φ30 mm×40 mm and the whole size of the ion source is Φ180 mm×130 mm. This source has a unique structure with the whole source body embedded into the extraction system. It can be operated in both continuous wave（CW） mode and pulse mode. In the CW mode, more than 20 m A hydrogen ion beam at 40 k V can be obtained with the microwave power of 180 W and about 1 m A hydrogen ion beam is produced with a microwave power of 10 W. In the pulse mode, more than50 m A hydrogen ion beam with a duty factor of 10% can be extracted when the peak microwave power is 1800 W.
文摘An electron cyclotron resonance ion source model that uses a coaxial antenna to inject the RF power was simulated, and the corresponding hydrogen plasma densities of the ion source were calculated at different magnetic field distributions via a fluid model. The results show that most of the microwave power is absorbed around the resonance surface near the antenna when the plasma density is below the cutoff density of 7.4 × 10^(16) m^(-3) for 2.45 GHz microwaves, and the simulation results also show that the plasma density is strongly influenced by the position and shape of the resonance surface, where a larger resonance surface would improve the plasma density.
基金Supported by the U.S.Department of Energy under contract DE-AC05-00OR22725 with UT-Battelle,LLC
文摘As clearly demonstrated at several laboratories,the performances of electron-cyclotron resonance (ECR)ion sources can be enhanced by increasing the physical sizes(volumes)of embedded ECR zones.En- larged ECR zones have been achieved by engineering the central magnetic field region of these sources so they are uniformly-distributed"volumes"in resonance with single-frequency rf power.Alternatively,the number of ECR surfaces in conventional minimum-B geometry sources can be increased by heating their plasmas with multiple,discrete frequency microwave radiation.Broadband rf power offers a simple,low cost and arguably more effective means for increasing the physical sizes of the ECR zones within the latter source type.In this article,theoretical arguments are made in support of the volume effect and the charge-state enhancing ef- fects of broadband microwave radiation(bandwidth:200MHz)plasma heating are demonstrated by comparing the high-charge-states of Ar ion beams,produced by powering a conventional minimum-B geometry,6.4GHz ECR ion source,equipped with a biased disk,with those produced by conventional bandwidth(bandwidth:～1.5MHz)radiation.
