arXiv - PHYS - Plasma Physics最新文献_第4页

Pump depletion and the Raman gap in ignition-scale plasmas 点火尺度等离子体中的泵耗和拉曼间隙

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-08 DOI: arxiv-2409.05232

S. H. Cao, M. J. Rosenberg, A. A. Solodov, H. Wen, C. Ren

引用次数: 0

Lectures on Statistical Mechanics 统计力学讲座

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-07 DOI: arxiv-2409.04899

Allan N. Kaufman, Bruce I. Cohen, Alain J. Brizard

引用次数: 0

Machine Learning for Chemistry Reduction in $text{N}_2-text{H}_2$ Low-Temperature Plasmas 在$text{N}_2-text{H}_2$低温等离子体中进行化学还原的机器学习

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-07 DOI: arxiv-2409.05914

Diogo R. Ferreira, Alexandre Lança, Luís Lemos Alves

引用次数: 0

Infra-red thermographic inversion in ST40 ST40 中的红外热成像反转

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-06 DOI: arxiv-2409.04278

Matteo Moscheni, Erik Maartensson, Matthew Robinson, Chris Marsden, Adrian Rengle, Travis Kelly Gray, Andrea Scarabosio, Elena Vekshina, Xin Zhang

{"title":"Infra-red thermographic inversion in ST40","authors":"Matteo Moscheni, Erik Maartensson, Matthew Robinson, Chris Marsden, Adrian Rengle, Travis Kelly Gray, Andrea Scarabosio, Elena Vekshina, Xin Zhang","doi":"arxiv-2409.04278","DOIUrl":"https://doi.org/arxiv-2409.04278","url":null,"abstract":"A new tool for infra-red thermographic inversion on Tokamak Energy's\u0000spherical tokamak, ST40, is developed in-house and here presented. Functional\u0000Analysis of Heat Flux (FAHF) is written in Python, and configured for multi-2D\u0000thermographic inversions, solving the heat conduction equation within the\u0000divertor tiles via the finite difference method, and leveraging an explicit\u0000time-marching scheme. Using infra-red camera data of the highest effective\u0000spatial resolution available, FAHF ultimately outputs the plasma perpendicular\u0000heat flux on the divertor, crucial quantity in any edge plasma investigation.\u0000In the present work, the internal numerics of the tool is first successfully\u0000verified by formal time and space convergence analyses, and corroborated by an\u0000energy balance assessment. A significant sensitivity of the perpendicular heat\u0000flux computed by FAHF to the user-selected spatial resolution is then\u0000evidenced. However, a precise heat flux is proved to be recoverable by ensuring\u0000a sufficiently high resolution. Last, the appropriateness of the model/geometry\u0000simplifications adopted in FAHF is successfully confirmed, by means of\u0000comparison against COMSOL Multiphysics simulations. FAHF is hence conclusively\u0000proven to qualify as a precise and accurate tool for infra-red thermographic\u0000inversions.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196036","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

Empirically extending 1D Child-Langmuir theory to a finite temperature beam 根据经验将一维 Child-Langmuir 理论扩展到有限温度梁

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-06 DOI: arxiv-2409.04355

Jesse M. Snelling, Gregory R. Werner, John R. Cary

{"title":"Empirically extending 1D Child-Langmuir theory to a finite temperature beam","authors":"Jesse M. Snelling, Gregory R. Werner, John R. Cary","doi":"arxiv-2409.04355","DOIUrl":"https://doi.org/arxiv-2409.04355","url":null,"abstract":"Numerical solutions to the 1D steady-state Vlasov-Poisson system are used to\u0000develop a straightforward empirical formula for the electric current density\u0000transmitted through a vacuum diode (voltage gap) as a function of gap distance,\u0000gap voltage, the injected current density, and the average velocity and\u0000temperature of injected particles, as well as their charge and mass. This\u0000formula generalizes the 1D cold beam Child-Langmuir law (which predicts the\u0000maximum transmitted current for mono-energetic particles in a planar diode as a\u0000function of gap voltage and distance) to the case where particles are injected\u0000with a finite velocity spread. Though this case is of practical importance, no\u0000analytical solution is known. Found by a best-fit to results from\u0000particle-in-cell (PIC) simulations, the empirical formula characterizes the\u0000current transmitted across the diode for an injected velocity distribution of a\u0000drifting Maxwellian. It is not meant to yield a precise answer, but\u0000approximately characterizes the effect of space charge on transmitted current\u0000density over a large input space. The formula allows quick quantitative\u0000estimation of the effect of space charge in diode-like devices, such as\u0000gate-anode gaps in nanoscale vacuum channel transistors.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"182 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196033","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

Macroscopic parameterization of positive streamer heads in air 空气中正流头的宏观参数化

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-06 DOI: arxiv-2409.04282

Dennis Bouwman, Jannis Teunissen, Ute Ebert

{"title":"Macroscopic parameterization of positive streamer heads in air","authors":"Dennis Bouwman, Jannis Teunissen, Ute Ebert","doi":"arxiv-2409.04282","DOIUrl":"https://doi.org/arxiv-2409.04282","url":null,"abstract":"The growth of streamers is determined at their heads, for individual\u0000streamers as well as in collective phenomena, such as streamer trees or coronas\u0000or streamer bursts ahead of lighting leaders. Some properties of the streamer\u0000heads, such as velocity v and radius R now can be measured quite well, but this\u0000is very challenging for others such as the maximal electric field, the charge\u0000content at the streamer head and the degree of chemical excitation and\u0000ionization in the streamer channel. Here we develop, test and evaluate a\u0000macroscopic approximation for positive streamer heads in air that relates\u0000macroscopic streamer head properties to each other. In particular, we find that\u0000velocity v, radius R and background field E_bg determine the complete profile\u0000of streamer heads with photoionization, if they propagate steadily. We also\u0000revisit Naidis' approximate relation between v, R and the maximal field E_max.\u0000The approximate head model consists of three first-order ordinary differential\u0000equations along the streamer axis. It is derived from the classical fluid model\u0000for streamer discharges by assuming axisymmetry, steady streamer propagation\u0000(with constant velocity and shape), and a (semi-)spherical shape of the charge\u0000layer. The model shows good agreement with solutions of the classical fluid\u0000model, even when it is applied to accelerating streamers. Therefore the model\u0000can be used for evaluations of experiments, like measurements of the maximal\u0000electric field, and it could be a valuable tool in constructing reduced models\u0000for the collective dynamics of many streamer discharges.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196034","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

Buoyant crystals halt the cooling of white dwarf stars 浮力晶体阻止白矮星冷却

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-06 DOI: arxiv-2409.04419

Antoine Bédard, Simon Blouin, Sihao Cheng

{"title":"Buoyant crystals halt the cooling of white dwarf stars","authors":"Antoine Bédard, Simon Blouin, Sihao Cheng","doi":"arxiv-2409.04419","DOIUrl":"https://doi.org/arxiv-2409.04419","url":null,"abstract":"White dwarfs are stellar remnants devoid of a nuclear energy source,\u0000gradually cooling over billions of years and eventually freezing into a solid\u0000state from the inside out. Recently, it was discovered that a population of\u0000freezing white dwarfs maintains a constant luminosity for a duration comparable\u0000to the age of the universe, signaling the presence of a powerful yet unknown\u0000energy source that inhibits the cooling. For certain core compositions, the\u0000freezing process is predicted to trigger a solid-liquid distillation mechanism,\u0000due to the solid phase being depleted in heavy impurities. The crystals thus\u0000formed are buoyant and float up, thereby displacing heavier liquid downward and\u0000releasing gravitational energy. Here we show that distillation interrupts the\u0000cooling for billions of years and explains all the observational properties of\u0000the unusual delayed population. With a steady luminosity surpassing that of\u0000some main-sequence stars, these white dwarfs defy their conventional portrayal\u0000as dead stars. Our results highlight the existence of peculiar merger remnants\u0000and have profound implications for the use of white dwarfs in dating stellar\u0000populations.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196040","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

Exploring the operational limits of Mirnov coil arrays in stellarators by means of a synthetic diagnostic 通过合成诊断探索恒星器中米尔诺夫线圈阵列的运行极限

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-06 DOI: arxiv-2409.04221

Pedro Pons-Villalonga, Álvaro Cappa, José Martínez-Fernández

{"title":"Exploring the operational limits of Mirnov coil arrays in stellarators by means of a synthetic diagnostic","authors":"Pedro Pons-Villalonga, Álvaro Cappa, José Martínez-Fernández","doi":"arxiv-2409.04221","DOIUrl":"https://doi.org/arxiv-2409.04221","url":null,"abstract":"A synthetic Mirnov coils diagnostic is presented and used to study the\u0000capabilities of the poloidal array of single-axis coils and the two helical\u0000arrays of tri-axial coils installed in the TJ-II stellarator. This tool\u0000integrates the plasma currents induced by Alfv'en-like perturbations of the\u0000electric potential inside the plasma and provides the induced magnetic field\u0000oscillations anywhere outside of it. The simulated signals can then be analyzed\u0000in the same manner as the experimental ones, and a scan on the radial position\u0000and width of the potential perturbation is conducted to find the limiting\u0000values that produce identifiable signals. We find, not surprisingly, that\u0000core-localized modes are indistinguishable from one another; and that the\u0000identification of low-n, low-m modes is often subject to off-by-one errors. We\u0000also determine the optimal polarization basis in which to analyze the tri-axial\u0000coils signals and address the diagnostic performance when resolving components\u0000of gap modes such as HAEs. Additionally, selected cases have been analyzed with\u0000a simplified plasma response model, showing that plasma shielding of the mode\u0000currents may further deteriorate the accuracy of the mode identification\u0000method. The code for this synthetic diagnostic, that can be easily used to\u0000conduct similar analysis for other devices, is publicly available in\u0000http://github.com/pponsv/synth_mirnov .","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196038","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

Propagation of strong electromagnetic waves in tenuous plasmas 强电磁波在粘性等离子体中的传播

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-06 DOI: arxiv-2409.04127

Emanuele Sobacchi, Masanori Iwamoto, Lorenzo Sironi, Tsvi Piran

引用次数: 0

Formation of high-aspect-ratio nanocavity in LiF crystal using a femtosecond of x-ray FEL pulse 利用飞秒 X 射线 FEL 脉冲在 LiF 晶体中形成高光谱比纳米腔

arXiv - PHYS - Plasma Physics Pub Date : 2024-09-05 DOI: arxiv-2409.03625

Sergey S. Makarov, Sergey A. Grigoryev, Vasily V. Zhakhovsky, Petr Chuprov, Tatiana A. Pikuz, Nail A. Inogamov, Victor V. Khokhlov, Yuri V. Petrov, Eugene Perov, Vadim Shepelev, Takehisa Shobu, Aki Tominaga, Ludovic Rapp, Andrei V. Rode, Saulius Juodkazis, Mikako Makita, Motoaki Nakatsutsumi, Thomas R. Preston, Karen Appel, Zuzana Konopkova, Valerio Cerantola, Erik Brambrink, Jan-Patrick Schwinkendorf, István Mohacsi, Vojtech Vozda, Vera Hajkova, Tomas Burian, Jaromir Chalupsky, Libor Juha, Norimasa Ozaki, Ryosuke Kodama, Ulf Zastrau, Sergey A. Pikuz

{"title":"Formation of high-aspect-ratio nanocavity in LiF crystal using a femtosecond of x-ray FEL pulse","authors":"Sergey S. Makarov, Sergey A. Grigoryev, Vasily V. Zhakhovsky, Petr Chuprov, Tatiana A. Pikuz, Nail A. Inogamov, Victor V. Khokhlov, Yuri V. Petrov, Eugene Perov, Vadim Shepelev, Takehisa Shobu, Aki Tominaga, Ludovic Rapp, Andrei V. Rode, Saulius Juodkazis, Mikako Makita, Motoaki Nakatsutsumi, Thomas R. Preston, Karen Appel, Zuzana Konopkova, Valerio Cerantola, Erik Brambrink, Jan-Patrick Schwinkendorf, István Mohacsi, Vojtech Vozda, Vera Hajkova, Tomas Burian, Jaromir Chalupsky, Libor Juha, Norimasa Ozaki, Ryosuke Kodama, Ulf Zastrau, Sergey A. Pikuz","doi":"arxiv-2409.03625","DOIUrl":"https://doi.org/arxiv-2409.03625","url":null,"abstract":"Sub-picosecond optical laser processing of metals is actively utilized for\u0000modification of a heated surface layer. But for deeper modification of\u0000different materials a laser in the hard x-ray range is required. Here, we\u0000demonstrate that a single 9-keV x-ray pulse from a free-electron laser can form\u0000a um-diameter cylindrical cavity with length of ~1 mm in LiF surrounded by\u0000shock-transformed material. The plasma-generated shock wave with TPa-level\u0000pressure results in damage, melting and polymorphic transformations of any\u0000material, including transparent and non-transparent to conventional optical\u0000lasers. Moreover, cylindrical shocks can be utilized to obtain a considerable\u0000amount of exotic high-pressure polymorphs. Pressure wave propagation in LiF,\u0000radial material flow, formation of cracks and voids are analyzed via continuum\u0000and atomistic simulations revealing a sequence of processes leading to the\u0000final structure with the long cavity. Similar results can be produced with\u0000semiconductors and ceramics, which opens a new pathway for development of laser\u0000material processing with hard x-ray pulses.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196042","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