arXiv - PHYS - Plasma Physics最新文献

{"title":"Thermo-electron accumulation in light and heavy water during MHz-burst laser ablation","authors":"Denys Moskal, Jiri Martan, Vladislav Lang, Milan Honner","doi":"arxiv-2409.03311","DOIUrl":"https://doi.org/arxiv-2409.03311","url":null,"abstract":"Laser-induced water ablation triggers various physical effects, including\u0000atom ionization, optical breakdown of the liquid, phase explosion, cavitation,\u0000and shockwave propagation. These effects can be further amplified in heavy\u0000water by deuterium-deuterium fusion reactions, which require extremely high\u0000energy levels. Laser pulses can be grouped in bursts to achieve the necessary\u0000energy within the ablation plasma plume. This study aims to compare the\u0000ablation plasma glow and thermal effects in light and heavy water under both\u0000single-pulse and burst-mode ultrashort laser irradiation. Notably, this\u0000research introduces the novel application of burst laser ablation in heavy\u0000water for the first time. The ablation was conducted beneath the water surface\u0000along a circular, laser-scanned trajectory, with two distinct ablation regimes:\u0000burst mode and single-pulse mode, utilizing lenses with varying focal lengths\u0000and different pulse durations. Absorption processes and plasma glow were\u0000monitored using visible and infrared detectors, a fast silicon detector, and a\u0000thermocouple. The study revealed that the burst regime in heavy water produced the most\u0000intense plasma glow when 1 ps laser pulses were used, with shorter pulses\u0000yielding less intense glow and the longest pulses yielding the least.\u0000Surprisingly, plasma glow at a lower initial power density of 2.6e13 W/cm2 was\u0000four times higher than at a higher power density of 8e13 W/cm2. These findings\u0000were compared with existing theories on plasma formation in water by ultrashort\u0000laser pulses. The observed increase in pulse-to-pulse plasma glow in burst mode\u0000was attributed to thermo-electron accumulation effects. The density of excited\u0000and hydrated electrons was calculated using both strong-field ionization and\u0000avalanche ionization models. Additionally, the influence of pulse parity on\u0000burst ablation glow in heavy water was discussed.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"396 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196045","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}

{"title":"Spot size dependent shock wave, plume and ion expansion dynamics of laser produced YBCO plasma","authors":"S. C. Singh, C. Fallon, P. Yeates, C. McLoughlin, J. T. Costello","doi":"arxiv-2409.03846","DOIUrl":"https://doi.org/arxiv-2409.03846","url":null,"abstract":"The expansion dynamics of laser produced plasma plumes in gaseous atmospheres\u0000exhibit information on plasma-ambient gas interactions which result in plume\u0000splitting, shock formation, sharpening and confinement. We investigate laser\u0000spot size variation on shock wave, plume, and ion dynamics from laser produced\u0000YBa2Cu3O7 (YBCO) plasmas using fast photography and Langmuir probe diagnosis.\u0000Changes in plume geometry are observed with varying focal spot size. At smaller\u0000spot sizes, lateral expansion of the plume is found to be larger, and plume\u0000expansion is spherical, while at larger spot sizes plume expansion is more\u0000cylindrical. Shock front formation time, relative intensity, spatial extent and\u0000total charge yield (TCY) are all dependent on laser spot size. Total charge\u0000yield (TCY) increases as the spot area increases, but decreases beyond a\u0000certain value. The width of the ion velocity distribution and the peak velocity\u0000decrease with increasing spot size, demonstrate that ions corresponding to\u0000larger spot sizes are somewhat more monoenergetic.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196039","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}

{"title":"Magnetic, Kinetic, and Transition regime: Spatially-segregated structure of compressive MHD turbulence","authors":"Guang-Xing Li, Mengke Zhao","doi":"arxiv-2409.02769","DOIUrl":"https://doi.org/arxiv-2409.02769","url":null,"abstract":"Turbulence is a complex physical process that emerges in multiple areas of\u0000modern physics, and in ionized environments such as interstellar gas, the\u0000magnetic field can be dynamically important. However, the exact function of the\u0000magnetic field in the ionized gas remains unclear. We use the $M_{rm A} =\u0000sqrt{E_{rm k}/E_B} $ to describe the importance of the magnetic field measured to the turbulent\u0000motion, and reveal diverse ways of mutual interaction. At low $M_{rm A}$\u0000(magnetic regime), the magnetic field is well-described as force-free. Despite\u0000the strong magnetic field, the motion of gas does not stay aligned with the\u0000magnetic field. At the regime of intermediate $M_{rm A}$ (magnetic-kinetic\u0000transition regime), the velocity field and the magnetic field exhibit the\u0000highest degree of alignment, which is likely the result of a rapid relaxation.\u0000At high $M_{rm A}$ (kinetic regime), both the magnetic field and the velocity\u0000field are irregular, with no alignment. We find observational counterparts to\u0000these regimes in observations of interstellar gas. The results highlight the\u0000diverse behavior of gas in MHD turbulence and guide future interpretations of\u0000the role of the magnetic field in astrophysical observations.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142195847","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}

{"title":"AI-Machine Learning-Enabled Tokamak Digital Twin","authors":"William Tang, Eliot Feibush, Ge Dong, Noah Borthwick, Apollo Lee, Juan-Felipe Gomez, Tom Gibbs, John Stone, Peter Messmer, Jack Wells, Xishuo Wei, Zhihong Lin","doi":"arxiv-2409.03112","DOIUrl":"https://doi.org/arxiv-2409.03112","url":null,"abstract":"In addressing the Department of Energy's April, 2022 announcement of a Bold\u0000Decadal Vision for delivering a Fusion Pilot Plant by 2035, associated software\u0000tools need to be developed for the integration of real world engineering and\u0000supply chain data with advanced science models that are accelerated with\u0000Machine Learning. An associated research and development effort has been\u0000introduced here with promising early progress on the delivery of a realistic\u0000Digital Twin Tokamak that has benefited from accelerated advances by the\u0000Princeton University AI Deep Learning innovative near-real-time simulators\u0000accompanied by technological capabilities from the NVIDIA Omniverse, an open\u0000computing platform for building and operating applications that connect with\u0000leading scientific computing visualization software. Working with the CAD files\u0000for the GA/DIII-D tokamak including equilibrium evolution as an exemplar\u0000tokamak application using Omniverse, the Princeton-NVIDIA collaboration has\u0000integrated modern AI/HPC-enabled near-real-time kinetic dynamics to connect and\u0000accelerate state-of-the-art, synthetic, HPC simulators to model fusion devices\u0000and control systems. The overarching goal is to deliver an interactive\u0000scientific digital twin of an advanced MFE tokamak that enables near-real-time\u0000simulation workflows built with Omniverse to eventually help open doors to new\u0000capabilities for generating clean power for a better future.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"66 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196044","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}

{"title":"Achievement of highly radiating plasma in negative triangularity and effect of reactor-relevant seeded impurities on confinement and transport","authors":"L. Casali, D. Eldon, T. Odstrcil, R. Mattes, A. Welsh, K. Lee, A. O. Nelson, C. Paz-Soldan, F. Khabanov, T. Cote, A. G. McLean, F. Scotti, K. E. Thome","doi":"arxiv-2409.02377","DOIUrl":"https://doi.org/arxiv-2409.02377","url":null,"abstract":"The first achievement of highly radiating plasmas in negative triangularity\u0000is shown with an operational space featuring high core radiation at high\u0000Greenwald fraction obtained with the injection of reactor-relevant seeded\u0000gases. These negative triangularity (NT) shape diverted discharges reach high\u0000values of normalized plasma pressure (BetaN > 2) at high radiation fraction\u0000with no ELMs. We demonstrate that as long as the impurity level in the core is\u0000kept low to avoid excessive fuel dilution and impurity accumulation,\u0000integration of NT configuration with high radiation fraction not only is\u0000achievable but it can lead to confinement improvement with stabilization\u0000effects originating from collisionality, ExB shear and profiles changes due to\u0000impurity radiation cooling. The underlying physics mechanism is robust and\u0000holds for a variety of impurity species. The absence of the requirement to stay\u0000in H-mode translates in a higher core radiation fraction potentially allowed in\u0000NT shape effectively mitigating the power exhaust issue. The results presented\u0000here demonstrate a path to high performance, ELM free and highly radiative\u0000regime with rector-relevant seeding gases making this regime a potential new\u0000scenario for reactor operation.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227738","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}

{"title":"Compression of high-power laser pulse leads to increase of electron acceleration efficiency","authors":"O. E. Vais, M. G. Lobok, V. Yu. Bychenkov","doi":"arxiv-2409.02671","DOIUrl":"https://doi.org/arxiv-2409.02671","url":null,"abstract":"Propagation of ultrarelativistically intense laser pulse in a self-trapping\u0000mode in a near critical density plasma makes it possible to produce electron\u0000bunches of extreme parameters appropriate for different state of art\u0000applications. Based on the 3D PIC simulations, it has been demonstrated how the\u0000best efficiency of electron acceleration in terms of the total charge of\u0000high-energy electrons and laser-to-electrons conversion rate can be achieved.\u0000For given laser pulse energy the universal way is a proper matching of laser\u0000hot spot size and electron plasma density to the laser pulse duration. The\u0000recommendation to achieve the highest yield of high-energy electrons is to\u0000compress laser pulse as much as possible. As example, compression of the few\u0000tens fs pulse to the 10 fs pulse leads to generation of the high-energy\u0000electron bunch with the highest total charge to exhibit conversion efficiency\u0000exceeding 50% for the Joule-level laser pulse energies.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225088","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}

{"title":"Slope of Magnetic Field-Density Relation as An Indicator of Magnetic Dominance","authors":"Mengke Zhao, Guang-Xing Li, Keping Qiu","doi":"arxiv-2409.02786","DOIUrl":"https://doi.org/arxiv-2409.02786","url":null,"abstract":"The electromagnetic field is a fundamental force in nature that regulates the\u0000formation of stars in the universe. Despite decades of efforts, a reliable\u0000assessment of the importance of the magnetic fields in star formation relations\u0000remains missing. In star-formation research, our acknowledgment of the\u0000importance of magnetic field is best summarized by the Cruther+ 2010 B-rho\u0000relation. The relation is either interpreted as proof of the importance of a\u0000magnetic field in the collapse, or the result of self-similar collapse where\u0000the role of the magnetic is secondary to gravity. Using simulations, we find a\u0000fundamental relation, ${cal M}_{rm A}$-k$_{B-rho}$(slope of $B-rho$\u0000relation) relation. This fundamental B-$rho$-slope relation enables one to\u0000measure the Alfv'enic Mach number, a direct indicator of the importance of the\u0000magnetic field, using the distribution of data in the B-$rho$ plane. It allows\u0000us to drive the following empirical $B-rho$ relation begin{equation} frac{B}{B_c} = {rm exp}left(left(frac{gamma}{{cal\u0000K}}right)^{-1}left( frac{rho}{rho_c}right)^frac{gamma}{{cal\u0000K}}right)nonumber, end{equation} which offers an excellent fit to the\u0000Cruther et al. data, where we assume ${cal M}_{rm A}-rho$ relation. The\u0000foundational ${cal M}_{rm A}-{rm k}_{B-rho}$ relation provides an\u0000independent way to measure the importance of magnetic field against the\u0000kinematic motion using multiple magnetic field measurements. Our approach\u0000offers a new interpretation of Cruther+2010, where a gradual decrease in the\u0000importance of B at higher densities is implied.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"62 6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196060","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}

{"title":"Evolution of radiation profiles in a strongly baffled divertor on MAST Upgrade","authors":"Fabio Federici, Matthew L. Reinke, Bruce Lipschultz, Jack J. Lovell, Kevin Verhaegh, Cyd Cowley, Mike Kryjak, Peter Ryan, Andrew J. Thornton, James R. Harrison, Byron J. Peterson, Bartosz Lomanowski, Jeremy D. Lore, Yacopo Damizia","doi":"arxiv-2409.02837","DOIUrl":"https://doi.org/arxiv-2409.02837","url":null,"abstract":"Plasma detachment involves interactions of the plasma with impurities and\u0000neutral particles, leading to significant losses of plasma power, momentum, and\u0000particles. Accurate mapping of plasma emissivity in the divertor and X-point\u0000region is essential for assessing the relationship between particle flux and\u0000radiative detachment. The recently validated InfraRed Video Bolometer (IRVB)\u0000diagnostic, in MAST-U enables this mapping with higher spatial resolution than\u0000more established methods like resistive bolometers. In previous preliminary\u0000work, the evolution of radiative detachment was characterised in L-mode (power\u0000entering the scrape-off layer, PSOL ~0.4MW). With a conventional divertor the\u0000inner leg consistently detached ahead of the outer leg, and radiative\u0000detachment preceded particle flux detachment. This work presents results also\u0000from the third MAST-U experimental campaign, fuelled from the low field side\u0000instead of the high field side, including Ohmic and beam heated L-mode shots\u0000(with a power exiting the core up to PSOL ~1-1.5MW). The radiation peak moves\u0000upstream from the target at lower upstream densities than the ion target flux\u0000roll-over (typically considered the detachment onset), while the inner leg\u0000detaches before the outer one. The movement of the radiation is in partial\u0000agreement with the expectations from the DLS model, predicting a sudden shift\u0000from the target to the X-point. The energy confinement is found to be related\u0000to detachment, but there seems to be some margin between the radiation on the\u0000inner leg reaching the X-point and confinement being affected, a beneficial\u0000characteristic if it could be extrapolated to future reactors. For increasing\u0000PSOL the particle flux roll over is almost unaffected, while radiative\u0000detachment occurs at higher density in both legs, but much higher on the outer,\u0000suggesting an uneven distribution of the power exiting the core.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142225087","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}

{"title":"Biermann-battery driven magnetized collisionless shock precursors in laser produced plasmas","authors":"Timothy Johnson, Graeme Sutcliffe, Jacob Pearcy, Andrew Birkel, Gabriel Rigon, Neel Kabadi, Brandon Lahmann, Patrick Adrian, Benjamin Reichelt, Justin Kunimune, Skylar Dannhoff, Matt Cufari, Frank Tsung, Hui Chen, Joseph Katz, Vladimir Tikhonchuk, Chikang Li","doi":"arxiv-2409.03076","DOIUrl":"https://doi.org/arxiv-2409.03076","url":null,"abstract":"This letter reports the first complete observation of magnetized\u0000collisionless shock precursors formed through the compression of\u0000Biermann-battery magnetic fields in laser produced plasmas. At OMEGA, lasers\u0000produce a supersonic CH plasma flow which is magnetized with Biermann-battery\u0000magnetic fields. The plasma flow collides with an unmagnetized hydrogen gas jet\u0000plasma to create a magnetized shock precursor. The situation where the flowing\u0000plasma carries the magnetic field is similar to the Venusian bow shock. Imaging\u00002$omega$ Thomson scattering confirms that the interaction is collisionless and\u0000shows density and temperature jumps. Proton radiographs have regions of strong\u0000deflections and FLASH magnetohydrodynamic (MHD) simulations show the presence\u0000of Biermann fields in the Thomson scattering region. Electrons are accelerated\u0000to energies of up to 100 keV in a power-law spectrum. OSIRIS particle-in-cell\u0000(PIC) simulations, initialized with measured parameters, show the formation of\u0000a magnetized shock precursor and corroborate the experimental observables.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196074","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}

{"title":"Characterizing the negative triangularity reactor core operating space with integrated modeling","authors":"H. S. Wilson, A. O. Nelson, J. McClenaghan, P. Rodriguez-Fernandez, J. Parisi, C. Paz-Soldan","doi":"arxiv-2409.03038","DOIUrl":"https://doi.org/arxiv-2409.03038","url":null,"abstract":"NT experiments have demonstrated core performance on par with positive\u0000triangularity (PT) H-mode without edge-localized modes (ELMs), encouraging\u0000further study of an NT reactor core. In this work, we use integrated modeling\u0000to scope the operating space around two NT reactor strategies: a high-field,\u0000compact fusion pilot plant concept and a low field, high aspect ratio concept.\u0000By integrating equilibrium, core transport, and edge ballooning instability\u0000models, we establish a range of operating points with less than 50 MW\u0000scrape-off layer power and fusion power comparable to positive triangularity\u0000(PT) H-mode reactor concepts. Heating and seeded impurities are leveraged to\u0000accomplish the same fusion performance and scrape-off layer exhaust power for\u0000various pressure edge boundary conditions. Scans over these pressure edge\u0000conditions accommodate any current uncertainty of the properties of the NT edge\u0000and show that the performance of an NT reactor will be extremely dependent on\u0000the edge pressure. The high-field case is found to enable lower scrape-off\u0000layer power because it is capable of reaching high fusion powers at a\u0000relatively compact size, which allows increased separatrix density without\u0000exceeding the Greenwald density limit. An increase in fusion power density is\u0000seen at weaker NT. Infinite-n ballooning instability models indicate that an NT\u0000reactor core can reach fusion powers comparable to leading PT H-mode reactor\u0000concepts while remaining ballooning-stable. Seeded krypton is leveraged to\u0000further lower scrape-off layer power since NT does not have a requirement to\u0000remain in H-mode. We contextualize the NT reactor operating space by comparing\u0000to popular PT H-mode reactor concepts, and find that NT exhibits competitive\u0000ELM-free performance with these concepts for a variety of edge conditions while\u0000maintaining relatively low scrape-off layer power.","PeriodicalId":501274,"journal":{"name":"arXiv - PHYS - Plasma Physics","volume":"185 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142196043","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}