Vacuum arc ion sources are known for delivering high currents of ion beams in many technological applications. There is a great need in the present ion accelerator injection research for a titanium vacuum arc source t...Vacuum arc ion sources are known for delivering high currents of ion beams in many technological applications. There is a great need in the present ion accelerator injection research for a titanium vacuum arc source to produce high-ionized plasma, in which its parameter is extremely important to match the extractors geometry and the extraction voltage. In this paper, the radial and angular distributions of the titanium cathodic vacuum arc plasma parameters are measured by a cylindrical Langmuir probe and analyzed by the Druyvesteyn method from the I-V curves. The electron density ne is about 10^（17）m^（-3） and the effective electron temperature Tefr is in the range of 6.12-11.11 eV in the free expansion cup before the ion extraction. The measured distribution of ne over the expansion cross-section is non-uniform and axially unsymmetrical with its form similar to the Gaussian distribution, and most of the plasma is concentrated into an area whose radius is smaller than 5 mm. Teff has a nearly uniform distribution over the expansion cross-section during the discharge. The results of the plasma parameters＇ non-uniformity encourage the researchers to make some optimization designs to improve the parameter distributions, and then to facilitate ion extraction.展开更多
Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteri...Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy.展开更多
This paper theoretically studies the effects of the vacuum-induced coherence on one- and two-photon absorption in a four-level atomic medium. It finds that the one- and two-photon absorption and amplification properti...This paper theoretically studies the effects of the vacuum-induced coherence on one- and two-photon absorption in a four-level atomic medium. It finds that the one- and two-photon absorption and amplification properties are quite sensitive to the vacuum-induced coherence. It is also shown that the one- and two-photon absorption spectra can be dramatically affected by modulating the relative phase of the applied fields, With the proper choice of the relative phase, the amplification without inversion for the probe field can be realized.展开更多
为了能够准确地判断真空灭弧室的在线工作状态,本文基于屏蔽罩电位法原理研制了一种高精度耦合电容传感探头来采集灭弧室屏蔽罩上的交流电位信号;搭建了一套真空标定系统,获得了传感探头输出电压与真空度压强之间对应关系的拟合公式;基...为了能够准确地判断真空灭弧室的在线工作状态,本文基于屏蔽罩电位法原理研制了一种高精度耦合电容传感探头来采集灭弧室屏蔽罩上的交流电位信号;搭建了一套真空标定系统,获得了传感探头输出电压与真空度压强之间对应关系的拟合公式;基于所获得的拟合公式,设计了一套基于DSP F2812和STM32为微处理器的真空度在线检测系统。系统采用无线通信模块nRF24L01传输数据,解决了高电压复杂磁场下的数据传输等问题。试验结果表明,在6 k V高压环境下,该系统能够完成在10-2Pa真空度压强范围内的测量,其精度能够满足大部分的工程实际应用。展开更多
文摘Vacuum arc ion sources are known for delivering high currents of ion beams in many technological applications. There is a great need in the present ion accelerator injection research for a titanium vacuum arc source to produce high-ionized plasma, in which its parameter is extremely important to match the extractors geometry and the extraction voltage. In this paper, the radial and angular distributions of the titanium cathodic vacuum arc plasma parameters are measured by a cylindrical Langmuir probe and analyzed by the Druyvesteyn method from the I-V curves. The electron density ne is about 10^（17）m^（-3） and the effective electron temperature Tefr is in the range of 6.12-11.11 eV in the free expansion cup before the ion extraction. The measured distribution of ne over the expansion cross-section is non-uniform and axially unsymmetrical with its form similar to the Gaussian distribution, and most of the plasma is concentrated into an area whose radius is smaller than 5 mm. Teff has a nearly uniform distribution over the expansion cross-section during the discharge. The results of the plasma parameters＇ non-uniformity encourage the researchers to make some optimization designs to improve the parameter distributions, and then to facilitate ion extraction.
文摘Generation characteristics of vacuum discharge plasma are very important for the applied research of metal plasma. The vacuum discharge electrode configuration and the cathode material affect the generation characteristics of the metal plasma which consists of metal ions coming from cathode and generated by vacuum discharge. In this research, the generation characteristics of the metal plasma generated by vacuum discharge are discussed for four patterns of electrode configurations, i.e. cone-mesh electrode setup, cone-cross line electrode setup, cone-line electrode setup and cone-ring electrode setup. Characteristics of the metal plasma, such as elec- tron density, electron temperature, space potential, ion energy, are measured by the probe method for discussing the impacts of different electrode configurations on the density of generated metal plasma. Moreover, the diffusion velocities of the metal plasma are measured for cathode materials of Pb, Al, and Cu, respectively. The experimental results indicate that the plasma generated by the discharge of cone-ring electrode configuration possesses the maximum density and the metal plasma generated by the Al cathode possesses the fastest diffusion velocity and the highest kinetic energy.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10575040 and 90503010）.Acknowledgments The authors would like to thank Dr Wu Ying for helpful discussions.
文摘This paper theoretically studies the effects of the vacuum-induced coherence on one- and two-photon absorption in a four-level atomic medium. It finds that the one- and two-photon absorption and amplification properties are quite sensitive to the vacuum-induced coherence. It is also shown that the one- and two-photon absorption spectra can be dramatically affected by modulating the relative phase of the applied fields, With the proper choice of the relative phase, the amplification without inversion for the probe field can be realized.
基金Ministry of Education Returned Overseas Stuff to Start Research and Fund Projects(E07C30010)High Energy,High Density,High Valence Vacuum Discharge Plasma Research Projects(EJ06014)
文摘为了能够准确地判断真空灭弧室的在线工作状态,本文基于屏蔽罩电位法原理研制了一种高精度耦合电容传感探头来采集灭弧室屏蔽罩上的交流电位信号;搭建了一套真空标定系统,获得了传感探头输出电压与真空度压强之间对应关系的拟合公式;基于所获得的拟合公式,设计了一套基于DSP F2812和STM32为微处理器的真空度在线检测系统。系统采用无线通信模块nRF24L01传输数据,解决了高电压复杂磁场下的数据传输等问题。试验结果表明,在6 k V高压环境下,该系统能够完成在10-2Pa真空度压强范围内的测量,其精度能够满足大部分的工程实际应用。
