Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4590700
E. Wyndham, M. Favre, G. Avaria, F. Guzman, H. Bhuyan, H. Chuaqui, S. Zakharov, P. Choi
Summary form only given. We present a series of observations of a small very low inductance sub-joule capillary discharge in a variety of different geometries and under a variety of operating conditions. The plasmas emit mainly in the corresponding filling gas and whose temperature attains about 20 eV for a few nanoseconds. However under certain modes of operation the strong axial electron beam associated with transient hollow cathode mechanism guides and interacts with the pinch plasma to give intense emission from higher ionization states. The spectra presented are for operation in Argon at stored driver energies from 60 to 500 mJ and additionally show a significant dependance on the repetition rate as well as the operating pressure and pressure gradient between the hollow cathode entrance aperture and the anode exit of the capillary. Inspite of the mm diameter of the capillary bore, emission from ablated alumina wall material is minimal for some geometrical configurations conforming to theoretical modelling of the discharge. In addition the electron beam and plasma jet emanating from the anode and propagating in the partially ionized argon may be observed from its optical emission and at the lowest discharge energies may be cuantified from time resolved double Langmuir probe observations.
{"title":"The soft X-ray spectrum and plasma jet properties in a range of sub-joule capillary discharges operated in argon","authors":"E. Wyndham, M. Favre, G. Avaria, F. Guzman, H. Bhuyan, H. Chuaqui, S. Zakharov, P. Choi","doi":"10.1109/PLASMA.2008.4590700","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590700","url":null,"abstract":"Summary form only given. We present a series of observations of a small very low inductance sub-joule capillary discharge in a variety of different geometries and under a variety of operating conditions. The plasmas emit mainly in the corresponding filling gas and whose temperature attains about 20 eV for a few nanoseconds. However under certain modes of operation the strong axial electron beam associated with transient hollow cathode mechanism guides and interacts with the pinch plasma to give intense emission from higher ionization states. The spectra presented are for operation in Argon at stored driver energies from 60 to 500 mJ and additionally show a significant dependance on the repetition rate as well as the operating pressure and pressure gradient between the hollow cathode entrance aperture and the anode exit of the capillary. Inspite of the mm diameter of the capillary bore, emission from ablated alumina wall material is minimal for some geometrical configurations conforming to theoretical modelling of the discharge. In addition the electron beam and plasma jet emanating from the anode and propagating in the partially ionized argon may be observed from its optical emission and at the lowest discharge energies may be cuantified from time resolved double Langmuir probe observations.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77585049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4591135
I. Chernyavskiy, A. Vlasov, T. Antonsen, S. Cooke, D. Abe, B. Levush, K. Nguyen
Summary form only given. TESLA (telegraphist's equations solution for linear-beam amplifiers) is a large-signal 2.5 D code successfully applied to the modeling of single beam and multiple beam klystron amplifiers. The current implementation of TESLA is based on the Fortran-95 language with a wide use of dynamically allocated memory. Advanced performance of the code together with highly efficient use of computer memory, user- friendly Python-based GUI and set of post-processing tools makes the TESLA package very useful as a primary design tool. Recent improvement in the TESLA model allows to accurately model the effects of slow and reflected particles, whose contribution becomes especially important for the simulation of high-efficiency devices. In addition, the extension of the code to a parallel version enables us to model beams in separate parallel processes. This allows more accurate simulation of multiple beam klystrons, having a large spread in the values of R/Q for the different beam- tunnels of the resonant cavities. The results of TESLA modeling of several devices and comparison with available experimental data are discussed.
只提供摘要形式。TESLA (telegraphist’s equations solution for linear-beam amplifiers)是一种大信号2.5 D码，成功地应用于单束和多束速调管放大器的建模。当前TESLA的实现是基于Fortran-95语言，广泛使用动态分配内存。代码的高级性能加上高效使用计算机内存，用户友好的基于python的GUI和一组后处理工具使TESLA包作为主要设计工具非常有用。最近对特斯拉模型的改进可以精确地模拟慢速和反射粒子的影响，这对模拟高效率器件的贡献尤为重要。此外，将代码扩展到并行版本使我们能够在单独的并行过程中对光束进行建模。这允许更准确地模拟多束速调管，在共振腔的不同光束隧道的R/Q值有很大的分布。讨论了几种器件的特斯拉建模结果，并与现有实验数据进行了比较。
{"title":"Single and multiple beam klystron modeling with TESLA","authors":"I. Chernyavskiy, A. Vlasov, T. Antonsen, S. Cooke, D. Abe, B. Levush, K. Nguyen","doi":"10.1109/PLASMA.2008.4591135","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591135","url":null,"abstract":"Summary form only given. TESLA (telegraphist's equations solution for linear-beam amplifiers) is a large-signal 2.5 D code successfully applied to the modeling of single beam and multiple beam klystron amplifiers. The current implementation of TESLA is based on the Fortran-95 language with a wide use of dynamically allocated memory. Advanced performance of the code together with highly efficient use of computer memory, user- friendly Python-based GUI and set of post-processing tools makes the TESLA package very useful as a primary design tool. Recent improvement in the TESLA model allows to accurately model the effects of slow and reflected particles, whose contribution becomes especially important for the simulation of high-efficiency devices. In addition, the extension of the code to a parallel version enables us to model beams in separate parallel processes. This allows more accurate simulation of multiple beam klystrons, having a large spread in the values of R/Q for the different beam- tunnels of the resonant cavities. The results of TESLA modeling of several devices and comparison with available experimental data are discussed.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80039297","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4591094
G.R. Shyeganrad, L. Mashhadi
Anomalous changes in radon concentration of ground water have been observed prior to certain large earthquakes. Temporal variation of radon gas concentration with probability of earthquake occurring have been previously investigated. Here we proposed a flexible method based on Laser-induced plasma spectroscopy (LIPS) for earthquake prediction by real time measurement concentration of radon gas solution in the underground water. Using fundamental harmonic Q-switched Nd:YAG laser, radon concentration fluctuation in the under ground water can be analyzed via observation of radon emission at 705.5 and 745 nm.
{"title":"Real time radon monitoring in the underground waters for earthquake prediction using laser-induced plasma spectroscopy (LIBS)","authors":"G.R. Shyeganrad, L. Mashhadi","doi":"10.1109/PLASMA.2008.4591094","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591094","url":null,"abstract":"Anomalous changes in radon concentration of ground water have been observed prior to certain large earthquakes. Temporal variation of radon gas concentration with probability of earthquake occurring have been previously investigated. Here we proposed a flexible method based on Laser-induced plasma spectroscopy (LIPS) for earthquake prediction by real time measurement concentration of radon gas solution in the underground water. Using fundamental harmonic Q-switched Nd:YAG laser, radon concentration fluctuation in the under ground water can be analyzed via observation of radon emission at 705.5 and 745 nm.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80248813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4590742
T. Berghofer, C. Eing, B. Flickinger, C. Gusbeth, R. Strassner, W. Frey, S. Schneider
Annine-6, a voltage sensitive dye, was used to evaluate the transmembrane potential sensitivity of different mammalian cell lines (KEK293, 22Rv1, and HeLa). Transmembrane potential was measured at different field strengths. To guarantee the comparability with theoretical charging models, the measurements have been performed well below the assumed critical value for incipient pore formation of approximately 1 kV/cm for a typical cell-diameter of 15 micrometer.A good agreement between theoretical predictions and data has been found considering the general shape of the measured curve, whereas discrepancies occurred considering the absolute amplitude.
{"title":"Transmembrane potential measurements on mammalian cells using the voltage sensitive dye annine-6","authors":"T. Berghofer, C. Eing, B. Flickinger, C. Gusbeth, R. Strassner, W. Frey, S. Schneider","doi":"10.1109/PLASMA.2008.4590742","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590742","url":null,"abstract":"Annine-6, a voltage sensitive dye, was used to evaluate the transmembrane potential sensitivity of different mammalian cell lines (KEK293, 22Rv1, and HeLa). Transmembrane potential was measured at different field strengths. To guarantee the comparability with theoretical charging models, the measurements have been performed well below the assumed critical value for incipient pore formation of approximately 1 kV/cm for a typical cell-diameter of 15 micrometer.A good agreement between theoretical predictions and data has been found considering the general shape of the measured curve, whereas discrepancies occurred considering the absolute amplitude.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81512718","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4590918
Z. Araoud, B. Ben Hamida, K. Charrada, G. Zissis
A two-dimensional fluid model has been used to investigate the thermal and dynamic behavior of a high pressure mercury lamp during the high pressure phase. Among the various important mechanisms present in the arc, natural convection effect plays a pivotal role in determining the qualitative as well as quantitative distribution of the temperature field. By being able to contrast the solutions with and without the convection effect, the exact influence of the convection can be established. Based from the results, it is shown that convection slows the warm-up time.
{"title":"Theoretical investigation of the warm-up phase of a high pressure mercury lamp","authors":"Z. Araoud, B. Ben Hamida, K. Charrada, G. Zissis","doi":"10.1109/PLASMA.2008.4590918","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590918","url":null,"abstract":"A two-dimensional fluid model has been used to investigate the thermal and dynamic behavior of a high pressure mercury lamp during the high pressure phase. Among the various important mechanisms present in the arc, natural convection effect plays a pivotal role in determining the qualitative as well as quantitative distribution of the temperature field. By being able to contrast the solutions with and without the convection effect, the exact influence of the convection can be established. Based from the results, it is shown that convection slows the warm-up time.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81609637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4591190
L. Merensky, A. Kardo-Sysoev, A. Flerov, A. Pokryvailo, D. Shmilovitz, A. Kesar
A state-of-the-art, all-solid-state sub-nanosecond pulse generator is presented. The generator is characterized by three compression stages. The first stage uses a power MOSFET that initially provides current increase in the storage inductor and then breaks the current. The second stage uses a 3 kV drift step recovery diode that cuts the reverse current rapidly to create a less than 1 nanosecond rise time pulse to charge a peaking capacitor. In the last stage, a silicon-avalanche shaper is used as a fast closing switch to discharge the capacitor. A 100 ps rise time, 1.5 kV output with 250 ps FWHM to a 50 Ohm load was achieved at a high pulse repetition frequency of up to 60 kHz with low < 30 ps jitter. The optimization and characterization of this generator will be presented.
{"title":"Optimization and characterization of a 1.5 kV, 100 sp rise time, all-solid-state pulse generator","authors":"L. Merensky, A. Kardo-Sysoev, A. Flerov, A. Pokryvailo, D. Shmilovitz, A. Kesar","doi":"10.1109/PLASMA.2008.4591190","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591190","url":null,"abstract":"A state-of-the-art, all-solid-state sub-nanosecond pulse generator is presented. The generator is characterized by three compression stages. The first stage uses a power MOSFET that initially provides current increase in the storage inductor and then breaks the current. The second stage uses a 3 kV drift step recovery diode that cuts the reverse current rapidly to create a less than 1 nanosecond rise time pulse to charge a peaking capacitor. In the last stage, a silicon-avalanche shaper is used as a fast closing switch to discharge the capacitor. A 100 ps rise time, 1.5 kV output with 250 ps FWHM to a 50 Ohm load was achieved at a high pulse repetition frequency of up to 60 kHz with low < 30 ps jitter. The optimization and characterization of this generator will be presented.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84215091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4590739
P. Rutberg, V. L. Gorjachev, V. Kolikov, V. Snetov, A. Stogov
For last two decades at IEE RAS the investigations of pulsed electric discharges (PED) in water and study of physical, chemical and biological properties of oxide nanoparticles water dispersions produced at electrodischarge treatment of water were carried out. Parameters of PED were next: duration 0.2-27 mus; current 30-1200 A, and current rate 106-109 A/s. As temperature of the discharge channel is ~104 K, it is source of UV irradiation. At absorption of UV irradiation H2O2, OH radicals, O, O3 and other substances are formed. All factors above destroy a lot of microorganisms and spores of pathogen microscopic fungi. It was determined that the prolonged microbic resistance of water (PMRW) treated by PED is caused by oxide nanoparticles and toxic ions of electrodes metal. It was shown also that the essential role in this phenomenon plays the surface electric charge of nanoparticles. Relations between: bactericidal action of water and mass concentration of nanoparticles in dependence on metal of electrodes; properties of nanoparticles as a function of electric discharges parameters and other initial parameters had been established. In the future it is supposed to execute investigations of nanoparticles water dispersions interaction with various biological objects including tumoral tissues.
{"title":"Pulsed electric discharges in water: Results and prospects","authors":"P. Rutberg, V. L. Gorjachev, V. Kolikov, V. Snetov, A. Stogov","doi":"10.1109/PLASMA.2008.4590739","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590739","url":null,"abstract":"For last two decades at IEE RAS the investigations of pulsed electric discharges (PED) in water and study of physical, chemical and biological properties of oxide nanoparticles water dispersions produced at electrodischarge treatment of water were carried out. Parameters of PED were next: duration 0.2-27 mus; current 30-1200 A, and current rate 106-109 A/s. As temperature of the discharge channel is ~104 K, it is source of UV irradiation. At absorption of UV irradiation H2O2, OH radicals, O, O3 and other substances are formed. All factors above destroy a lot of microorganisms and spores of pathogen microscopic fungi. It was determined that the prolonged microbic resistance of water (PMRW) treated by PED is caused by oxide nanoparticles and toxic ions of electrodes metal. It was shown also that the essential role in this phenomenon plays the surface electric charge of nanoparticles. Relations between: bactericidal action of water and mass concentration of nanoparticles in dependence on metal of electrodes; properties of nanoparticles as a function of electric discharges parameters and other initial parameters had been established. In the future it is supposed to execute investigations of nanoparticles water dispersions interaction with various biological objects including tumoral tissues.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84503476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4590983
R. Rezaei-Nasirabad, E. Yazdani, P. Zobdeh, R. Sadighi-Bonabi
This paper investigates that by using a new electron density transition in plasma, the wave breaking threshold was reduced and transversely electron injection into the acceleration phase of the wake field was increased. Numerical results identify that injected electron bunch causes to modification of the wake field. By optimization of transient length and injected charge of electron, electromagnetic propagation and electron density variation in plasma has been evaluated and the efficient energy and gain of electrons have been obtained.
{"title":"Electron trapping and field propagation in laser-plasma interaction with density transition","authors":"R. Rezaei-Nasirabad, E. Yazdani, P. Zobdeh, R. Sadighi-Bonabi","doi":"10.1109/PLASMA.2008.4590983","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4590983","url":null,"abstract":"This paper investigates that by using a new electron density transition in plasma, the wave breaking threshold was reduced and transversely electron injection into the acceleration phase of the wake field was increased. Numerical results identify that injected electron bunch causes to modification of the wake field. By optimization of transient length and injected charge of electron, electromagnetic propagation and electron density variation in plasma has been evaluated and the efficient energy and gain of electrons have been obtained.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84575059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4591132
M. Botton, T. Antonsen, S. Cooke, B. Levush, I. Chernyavskiy, A. Vlasov
NEPTUNE (Nonlinear Evolution of Particle Trajectories Under Non-stationary Excitation) is a new code under development for 3D time dependent large amplitude simulations of coherent radiation sources. The code deals mainly with the description of the beam tunnel where the interaction between the electron beam and the electromagnetic (EM) waves takes place. The EM fields are described by complex envelopes allowing several carrier frequencies which are all harmonics of some fundamental frequency. The fields are calculated self consistently with the electron beam as a source, using the ADI scheme. The ADI scheme is based on splitting the time step into two halves. In each sub-step Maxwell's equations are solved implicitly in one direction and explicitly in the perpendicular direction. The ADI scheme is unconditionally stable, thus the time step can be larger than the one imposed by the CFL condition. This allows, in principal, high spatial resolution required for high frequency cavities without extending the calculation time. Nevertheless, the ADI scheme requires a solution of six tri-diagonal equations for the electric field followed by derivation of the magnetic field. This increased complexity somewhat impairs the efficiency of the calculations. The boundary conditions on the six faces of the beam tunnel are general, and can be specified either as perfect conductor, symmetry boundary conditions or arbitrary external specification. The electron beam is described by a set of trajectories. The frozen-field approximation used for the solution of the equation of motion for these trajectories facilitates the calculations, but requires that the transit time of the electrons in the interaction domain is much shorter than the cavity fill time, as is the case in most of the coherent radiation sources. The resulting code is expected to be more efficient and requires modest computing power compared to conventional 3D particle-in-cell codes. Examples of the use of the code for dielectric loaded waveguide serving as a slow-wave amplifier are presented.
海王星(Non-stationary Excitation Nonlinear Evolution of Particle Trajectories Under Non-stationary Excitation)是一个正在开发的用于相干辐射源三维时间相关大振幅模拟的新程序。该代码主要描述电子束与电磁波相互作用发生的电子束隧道。电磁场是由复杂的包络来描述的，它允许几个载波频率，这些载波频率都是某个基频的谐波。以电子束为源，采用ADI格式自一致地计算了电场。ADI方案基于将时间步长分成两半。在每个子步骤中，麦克斯韦方程组在一个方向上隐式求解，在垂直方向上显式求解。ADI方案是无条件稳定的，因此时间步长可以大于CFL条件所施加的时间步长。原则上，这可以在不延长计算时间的情况下实现高频腔所需的高空间分辨率。然而，ADI方案需要六个电场的三对角线方程的解，然后推导磁场。这种增加的复杂性在一定程度上削弱了计算的效率。光束隧道的六个面边界条件是一般的，可以指定为完美导体、对称边界条件或任意外部规范。电子束用一组轨迹来描述。用于求解这些轨迹运动方程的冻结场近似简化了计算，但要求电子在相互作用域中的传递时间远短于空腔填充时间，这在大多数相干辐射源中都是如此。与传统的三维细胞内粒子编码相比，由此产生的编码预计将更高效，并且需要适度的计算能力。文中给出了将该代码用于介质加载波导作为慢波放大器的实例。
{"title":"Neptune: An efficient time dependent 3D simulations of coherent radiation sources","authors":"M. Botton, T. Antonsen, S. Cooke, B. Levush, I. Chernyavskiy, A. Vlasov","doi":"10.1109/PLASMA.2008.4591132","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591132","url":null,"abstract":"NEPTUNE (Nonlinear Evolution of Particle Trajectories Under Non-stationary Excitation) is a new code under development for 3D time dependent large amplitude simulations of coherent radiation sources. The code deals mainly with the description of the beam tunnel where the interaction between the electron beam and the electromagnetic (EM) waves takes place. The EM fields are described by complex envelopes allowing several carrier frequencies which are all harmonics of some fundamental frequency. The fields are calculated self consistently with the electron beam as a source, using the ADI scheme. The ADI scheme is based on splitting the time step into two halves. In each sub-step Maxwell's equations are solved implicitly in one direction and explicitly in the perpendicular direction. The ADI scheme is unconditionally stable, thus the time step can be larger than the one imposed by the CFL condition. This allows, in principal, high spatial resolution required for high frequency cavities without extending the calculation time. Nevertheless, the ADI scheme requires a solution of six tri-diagonal equations for the electric field followed by derivation of the magnetic field. This increased complexity somewhat impairs the efficiency of the calculations. The boundary conditions on the six faces of the beam tunnel are general, and can be specified either as perfect conductor, symmetry boundary conditions or arbitrary external specification. The electron beam is described by a set of trajectories. The frozen-field approximation used for the solution of the equation of motion for these trajectories facilitates the calculations, but requires that the transit time of the electrons in the interaction domain is much shorter than the cavity fill time, as is the case in most of the coherent radiation sources. The resulting code is expected to be more efficient and requires modest computing power compared to conventional 3D particle-in-cell codes. Examples of the use of the code for dielectric loaded waveguide serving as a slow-wave amplifier are presented.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85583384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2008-06-15DOI: 10.1109/PLASMA.2008.4591140
S. Point, É. Robert, S. Dozias, C. Cachoncinlle, R. Viladrosa, J. Pouvesle
Summary form only given. As mercury is a non environmental friendly element, many efforts are made in the field of light sources in order to replace Mercury-based lamps. This contribution deals with the potentialities of Neon Xenon discharges for replacing Mercury ones used in cold hollow cathodes fluorescent tubes. Interest of pulsed excitation (pulse duration: few mus; pulse frequency: few kHz) had been already shown in our previous works in comparison of AC mode. Following parametric studies on pressure (on the range 10 mbar-100 mbar) have shown that a pulsed Ne-Xe discharge at advanced pressure is able to provide close to 50% of illuminance provided by a mercury tube supplied with a 25 mA sinusoidal excitation current. Working times of thousands hours have been reached without significant decreasing of the luminous flux. Spectroscopic analysis and simple computed simulations have improved comprehension of mechanisms leading to the phosphor excitation, and permits to clarify results of parametric studies: in particular, neon partial pressure has been clearly identified as a fundamental parameter which determines the density of ionic excimers (essentially Xe2 +) whose recombination efficiently populates Xe first resonant level during post-discharge period. Its de- excitation to the ground level produces a significant VUV emission (147 nm) able to excite phosphor. As post- discharge emission typically occurs on few hundreds of mus, duty cycle must be adapted to fully recover VUV emission. Ignition processes have also been investigated. Strong influence of the excitation frequency on breakdown has been observed: residual electronic density from previous pulse increases with the frequency. Consequently, ignition in hollow cathode is accelerated and breakdown voltage decreases. Compromise has to be found between pulse frequency and duty cycle in order to have the breakdown voltage as low as possible while fully recovering post- discharge emission.
{"title":"Potentialities of neon xenon pulsed discharges for publicity and architectural lighting","authors":"S. Point, É. Robert, S. Dozias, C. Cachoncinlle, R. Viladrosa, J. Pouvesle","doi":"10.1109/PLASMA.2008.4591140","DOIUrl":"https://doi.org/10.1109/PLASMA.2008.4591140","url":null,"abstract":"Summary form only given. As mercury is a non environmental friendly element, many efforts are made in the field of light sources in order to replace Mercury-based lamps. This contribution deals with the potentialities of Neon Xenon discharges for replacing Mercury ones used in cold hollow cathodes fluorescent tubes. Interest of pulsed excitation (pulse duration: few mus; pulse frequency: few kHz) had been already shown in our previous works in comparison of AC mode. Following parametric studies on pressure (on the range 10 mbar-100 mbar) have shown that a pulsed Ne-Xe discharge at advanced pressure is able to provide close to 50% of illuminance provided by a mercury tube supplied with a 25 mA sinusoidal excitation current. Working times of thousands hours have been reached without significant decreasing of the luminous flux. Spectroscopic analysis and simple computed simulations have improved comprehension of mechanisms leading to the phosphor excitation, and permits to clarify results of parametric studies: in particular, neon partial pressure has been clearly identified as a fundamental parameter which determines the density of ionic excimers (essentially Xe2 +) whose recombination efficiently populates Xe first resonant level during post-discharge period. Its de- excitation to the ground level produces a significant VUV emission (147 nm) able to excite phosphor. As post- discharge emission typically occurs on few hundreds of mus, duty cycle must be adapted to fully recover VUV emission. Ignition processes have also been investigated. Strong influence of the excitation frequency on breakdown has been observed: residual electronic density from previous pulse increases with the frequency. Consequently, ignition in hollow cathode is accelerated and breakdown voltage decreases. Compromise has to be found between pulse frequency and duty cycle in order to have the breakdown voltage as low as possible while fully recovering post- discharge emission.","PeriodicalId":6359,"journal":{"name":"2008 IEEE 35th International Conference on Plasma Science","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2008-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85632334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：