2016 IEEE International Conference on Plasma Science (ICOPS)最新文献_第2页

Novel high-power radio-frequency sources for mobile ionospheric heating 用于移动电离层加热的新型大功率射频源

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534058

B. Beaudoin, J. A. Karakkad, Charles Turner, A. Narayan, C. Thompson, N. Goyal, G. Nusinovich, T. Antonsen

{"title":"Novel high-power radio-frequency sources for mobile ionospheric heating","authors":"B. Beaudoin, J. A. Karakkad, Charles Turner, A. Narayan, C. Thompson, N. Goyal, G. Nusinovich, T. Antonsen","doi":"10.1109/PLASMA.2016.7534058","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534058","url":null,"abstract":"The ionosphere plays an important role in the performance of critical civilian and defense communication systems. Perturbation studies of the ionosphere allow us to investigate the ionosphere and improve the performance of communications that rely on the ionosphere as well as develop new applications. A key instrument in ionospheric modification is the ionospheric heater, a powerful high frequency transmitter that perturbs the properties of the ionospheric plasma by modulating the electron temperature at preselected altitudes. The latest technology uses stationary facilities, among which HAARP is the largest. There are numerous benefits from using mobile ionospheric heaters (MIHs). Such a mobile system would allow investigators to conduct the research at different latitudes without building a costly permanent installation. These mobile sources would be substantially smaller than HAARP and located on a barge-size platform. A mobile heater for ionospheric modification studies requires a new megawatt class of RF (3-10 MHz) source operating with an antenna that is roughly 1/100 in area of a HAARP antenna [2]. In order to deliver to the ionosphere, an effective power density comparable to that of HAARP, the total source power must be in the range of up to 100 MW, placing a premium on efficiency. The present paper describes some of the technical advances in the development of such sources (inductive output tubes, IOTs): a novel electron gun, which allows the D-class operation of a MW-level IOT without interception of an electron beam by grid electrodes, a prototyping test-stand, two types of modulators capable of driving the mod-anode of a MW level gun and a tunable constant impedance cavity operating in the desired frequency range.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121724504","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}

引用次数: 0

Numerical investigation on nanoparticle formation and influence on size distribution in wire explosion process 金属丝爆炸过程中纳米颗粒形成及其对粒径分布影响的数值研究

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534042

J. Bai, Z. Shi, S. Jia, Xingwen Li, Lijun Wang

{"title":"Numerical investigation on nanoparticle formation and influence on size distribution in wire explosion process","authors":"J. Bai, Z. Shi, S. Jia, Xingwen Li, Lijun Wang","doi":"10.1109/PLASMA.2016.7534042","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534042","url":null,"abstract":"Wire explosion technique has been widely studied in recent years to produce nanoparticles of different materials due to the enormous outstanding characteristics of nanomaterials as well as the advantages of wire explosion technique1. In the wire explosion process for preparation of nanoparticles, the wire firstly melts, vaporizes and then generates a mixture of metal vapor and liquid droplets. The voltage reaches a peak amplitude and the current quickly drops because only a small amount of metal vapor ionizes at this moment. Then the metal vapor gets cooled down and starts the following growing process of nanoparticles. In this paper, following simulation is carried out with wire material of aluminum. In the first stage, the generation process of vapor particles is modeled and the relationship between the explosion temperature, resistive deposited energy, the size of the vapor particles and the parameters of the explosion is derived and compared with experimental data. We find the resistive deposited energy is below the ionization one and the size of the vapor particles at the moment of explosion increases as the explosion temperature and deposited energy increases. Base on the results of the first stage, the growing process of the metal vapor to nanoparticles is simulated by adopting nodal treatment. The three main growing process, including homogeneous nucleation, surface growth and coagulation, are investigated to predict the size distribution of nanoparticles. It shows that nuclei of small size are formed during nucleation process. The decrease of number density of vapor particles demonstrates that condensation plays a more significant role than evaporation in surface growth process. The size distributions of nanoparticles at different temperatures also demonstrate that the growing process of nanoparticles tends to be inactive when temperature becomes relatively low. The final size distribution of nanoparticles is compared with experimental data as well2.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128853214","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}

引用次数: 0

Microwave pulse compression experiments in a waveguide cavity with RF breakdown triggered switch 射频击穿触发开关波导腔中的微波脉冲压缩实验

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534403

S. Savaidis, S. Mitilineos, Z. Ioannidis, N. Stathopoulos

引用次数: 1

Plasma irradiation effects in the abdominal adhesion mouse model 等离子体辐照对腹腔粘连小鼠模型的影响

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534129

Keita Soda, T. Hamakubo, H. Yamashita, Kyungho Chang, Nobuyuki Shimizu

{"title":"Plasma irradiation effects in the abdominal adhesion mouse model","authors":"Keita Soda, T. Hamakubo, H. Yamashita, Kyungho Chang, Nobuyuki Shimizu","doi":"10.1109/PLASMA.2016.7534129","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534129","url":null,"abstract":"Plasma phenomenon has been demonstrated as a new promising tool in medical field, although little is known about the plasma irradiation effects on tissues in abdominal cavity. Therefore finding the possible marker is the first and the key step to evaluate the events after plasma irradiation and a suitable mouse model is required to validate the plasma effects. We focused on abdominal adhesion formation that is the secondary event after surgery irrespective of the any surgical devices, and is associated with complications such as ileus, abdominal pain or infertility. Firstly we generated a mouse abdominal adhesion model using bipolar forceps. Within 7days, cauterized cecum was demonstrated to recruit the epididymal adipose tissue (EAT), which connected tissues abnormally and infiltrated inflammatory cells into EAT were observed by microscopic examination. We also identified some inflammatory proteins released into peritoneal cavity by proteomics of ascites after cauterization. Moreover, we measured serum cytokines level and determined that adhesion could be evaluated as a result of the alteration of pro-inflammatory and anti-inflammatory cytokines. Now we are pursuing to assess the plasma irradiation effects using those inflammatory proteins and cytokines as an appropriate marker.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126884234","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}

引用次数: 0

Benchmarking multi-fluid plasma-electromagnetic models 对标多流体等离子体电磁模型

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534242

K. Beckwith, M. Kundrapu, P. Stoltz, J. Luginsland

{"title":"Benchmarking multi-fluid plasma-electromagnetic models","authors":"K. Beckwith, M. Kundrapu, P. Stoltz, J. Luginsland","doi":"10.1109/PLASMA.2016.7534242","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534242","url":null,"abstract":"Summary form only given. The dynamical behavior of plasmas is strongly dependent on frequency. At the lowest frequency the plasma is in the regime of magnetohydrodynamics (MHD) and has been the focus of extensive research in fluid plasma modeling in the past few decades. At somewhat higher frequencies, the electrons and ions can move relative to each other, behaving like two charge separated, interpenetrating fluids. This is the regime of high-frequency, non-neutral two-fluid physics and is relevant to high-density, fast MHD phenomena encountered in pulsed-power devices like dense plasma focus, Z-pinches, plasma thrusters and field-reversed configurations. Although initial work has been done on efficiently solving fast MHD phenomena, several open research problems remain. For example, implicit schemes developed for application in slow MHD can not be applied directly as pulsed-power devices commonly exhibit shocks and other sharp features in the flow. To meet this need, we have developed fully implicit schemes for solving the two fluid equations based on a combination of physics-based preconditioning and Jacobian-Free Newton Krylov solvers. Here, we present application of this approach to a range of problems, including shock physics, ambipolar expansion and shear flow. Results obtained from our approach will be compared to analytic theory and, where appropriate, magnetohydrodynamic and kinetic simulations.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132493951","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}

引用次数: 0

Theory of sheaths near positively biased electrodes 正偏压电极附近的鞘理论

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534341

B. Scheiner, S. Baalrud, B. Yee, M. Hopkins, E. Barnat

引用次数: 2

Electron density uniformity commensurate with B-dot uniformity verification measurements for a phase-locked, RF distributed current source control system 电子密度均匀性相称的b点均匀性验证测量锁相，射频分布电流源控制系统

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534057

D. Coumou, S. Shannon

引用次数: 0

Numerical simulation of the initial expansion process of cathode spots in high-current triggered vacuum arc 大电流触发真空电弧中阴极点初始膨胀过程的数值模拟

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534080

Cong Wang, Z. Shi, Bingzhou Wu, S. Jia, Lijun Wang

{"title":"Numerical simulation of the initial expansion process of cathode spots in high-current triggered vacuum arc","authors":"Cong Wang, Z. Shi, Bingzhou Wu, S. Jia, Lijun Wang","doi":"10.1109/PLASMA.2016.7534080","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534080","url":null,"abstract":"Summary form only given. The cathode spot (CS), as an intense source of inter-electrode arc plasma, plays a predominant role in maintaining the burning of vacuum arc, especially with an inactive anode. Consequently, the dynamics of CSs have a significant influence on the characteristics of the vacuum arc. Many experimental investigations have been devoted to better understanding of the motion of CSs, especially the initial expansion process of cathodes spots in high-current triggered vacuum arc. It has been indicated that the motion characteristic of cathode spots is greatly influenced by external axial magnetic field (AMF). In this work, a method is established to simulate the initial expansion process of CSs in high-current triggered vacuum arc, based on the proposed stepwise model of the motion of a single CS1. In this method, every new CS can be ignited in any direction around the old one with certain probability, which is connected with the magnetic field around the position of the old CS. With this approach, the initial expansion processes of CSs in free-burning and AMF-stabilized high-current triggered vacuum arc are simulated numerically with CSs initially uniformly distributed on a ring. The self-generated transverse magnetic field at the position of every CS is calculated by commercial software ANSYS with the current distribution in contact plate taken into account2. Simulation results agree well with relevant experiment results. Simulation results show that CSs expand faster without external AMF than that under AMF, and external AMF has significant influence on the distribution of CSs on the cathode surface, e.g., more and more CSs appear inside the ring when external AMF is present. Furthermore, the results also indicate that the expanding ring structure of CSs is unstable, and AMF can accelerate the breaking of the ring.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128727596","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}

引用次数: 0

Design and optimization of a liner-on-target injector for staged Z-pinch experiments using computational fluid dynamics and MHD simulations 利用计算流体动力学和MHD模拟技术，设计并优化了用于分段z夹紧实验的瞄准尾管喷射器

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7534113

J. Valenzuela, J. Narkis, F. Conti, I. Krasheninnikov, V. Fadeev, F. Beg, F. Wessel, H. Rahman, P. Ney, E. Mckee, T. Darling, A. Covington

{"title":"Design and optimization of a liner-on-target injector for staged Z-pinch experiments using computational fluid dynamics and MHD simulations","authors":"J. Valenzuela, J. Narkis, F. Conti, I. Krasheninnikov, V. Fadeev, F. Beg, F. Wessel, H. Rahman, P. Ney, E. Mckee, T. Darling, A. Covington","doi":"10.1109/PLASMA.2016.7534113","DOIUrl":"https://doi.org/10.1109/PLASMA.2016.7534113","url":null,"abstract":"Summary form only given. Previous Staged Z-pinch experiments have demonstrated that gas liners (or puffs) can efficiently couple energy to a target plasma and implode uniformly, producing plasmas in High Energy Density (HED) regimes. In these experiments, a 50 kJ, 1.5 MA, 1 μs current driver was used to implode a magnetized, Kr liner onto a D+ target, producing 1010 neutrons per shot. Time-of-flight data suggested that primary and secondary neutrons were produced. MHD simulations show that, using optimized liner and plasma target conditions, neutron yield could be further increased in Staged Z-pinch implosions using the Zebra machine, a 1.5 MA and 100 ns rise time current driver. In this work we present the design and optimization of an injector for these experiments. The injector is composed of an annular high atomic number (e.g. Ar, Kr) gas-puff and an on-axis plasma gun that delivers the ionized deuterium target. The gas-puff nozzle optimization was performed using the computational fluid dynamics (CFD) code Fluent and the MHD code MACH2. The CFD simulations produce density profiles as a function of the nozzle shape and gas. These profiles are initialized in MACH2 to find the optimal liner density profile for a stable, uniform implosion that produces high neutron yield.","PeriodicalId":424336,"journal":{"name":"2016 IEEE International Conference on Plasma Science (ICOPS)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128731097","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}

引用次数: 0

FIR polarimetry on the Alcator C-Mod tokamak

2016 IEEE International Conference on Plasma Science (ICOPS) Pub Date : 2016-08-08 DOI: 10.1109/PLASMA.2016.7533942

J. Irby

引用次数: 0