Physics of Plasmas最新文献

{"title":"An investigation of the anti-cancer effect of underwater air jets with different grounding methods","authors":"Tianji Ni, Renpu Ge, Xinyi Zhao, Xingzhu Zhang, Shuai Yuan, Z C Xu, Dehui Xu","doi":"10.1063/5.0308017","DOIUrl":"https://doi.org/10.1063/5.0308017","url":null,"abstract":"With the wide application of plasma-treated activated water in biomedicine in recent years, people have begun to explore how to prepare activated water efficiently. In this paper, we introduce a new idea of underwater plasma air jet to prepare activated water for anticancer use. Meanwhile, we compared the anticancer effect of underwater discharge of two different structural devices by changing the position of grounded electrodes. We photographed the evolution of the underwater jet using a high-speed camera and measured the generated free radicals by an emission spectrometer. We measured the physicochemical properties, including pH, oxidation–reduction potential, temperature, O3 concentration, and some active particles in the liquid-phase reaction, such as H2O2, NO2−, and NO3−, and the concentration of these active particles can indirectly reflect the anticancer effect. We use the activated water mixed medium to treat the cells for a certain period of time and test their activity after a period of time. Results show that the underwater discharge device with two grounding methods has a better anti-cancer effect. In order to find out the specific response of activated water against cancer, we measured the apoptosis and the concentration of intracellular reactive oxygen species (ROS) and found that the apoptosis rate of cells treated with activated water increased significantly and the concentration of intracellular ROS also increased. Therefore, the preparation of activated water by underwater air jets for anticancer purposes may be a novel plasma anticancer method.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"32 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147900900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms of OH and H2O2 formation in the liquid phase induced by an atmospheric pressure plasma jet with oxygen introduction","authors":"Wenhao Xi, H. Zhang, Wenxue Ren, Jingwen Li, Nuo Chen, Mian Chen, Wei Han, Cheng Cheng","doi":"10.1063/5.0268974","DOIUrl":"https://doi.org/10.1063/5.0268974","url":null,"abstract":"Atmospheric pressure plasmas exhibit broad potential for application in nanomaterial synthesis, water purification, and biomedicine. Investigating the mechanisms of plasma-induced generation and transformation of liquid-phase reactive species, particularly hydroxyl radicals (OH) and hydrogen peroxide (H2O2), is crucial for optimizing plasma-based applications. In this study, two plasma discharge modes were established: (a) Nor mode: direct liquid contact discharge and (b) Cut mode: conductor cutoff discharge. The concentrations of liquid-phase OH and H2O2 induced by helium and helium/oxygen mixture plasma jets were measured and analyzed using a combination of optical emission spectroscopy (OES), chemical trapping-fluorescence spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy. The results indicate significant differences in the generation of liquid-phase OH and H2O2 between the two discharge modes. Specifically, in (a) the Nor mode, the production of liquid-phase OH is considerably higher compared to (b) the Cut mode. Conversely, the concentration of liquid-phase H2O2 is higher in the cutoff discharge mode than in the direct contact mode. Additionally, the introduction of oxygen significantly suppresses the generation of both liquid-phase OH and H2O2. Comprehensive analysis of OES, fluorescence spectra, and EPR data reveals that the formation pathways of liquid-phase OH and H2O2 are closely related to the transport mechanisms of gas-phase reactive species in plasma, primarily resulting from the dissolution of gas-phase products into the liquid phase. Furthermore, dissolved atomic oxygen in the liquid phase interferes with HTA fluorescence detection, leading to inaccurate measurements of liquid-phase OH concentrations. This study elucidates the impact of oxygen introduction on the generation of OH and H2O2 induced by plasma and clarifies their generation and transformation mechanisms. It also discusses the limitations of conventional detection methods in complex atmospheres. These findings provide important theoretical insights and references for optimizing plasma applications in medicine and environmental fields.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"32 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147918290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced gamma-ray generation and collimation in laser-plasma interactions via a cone-channel target design","authors":"S. Chintalwad, D. J. Stark","doi":"10.1063/5.0273530","DOIUrl":"https://doi.org/10.1063/5.0273530","url":null,"abstract":"Recent advancements in high-intensity lasers have made all-optical nonlinear Compton scattering a promising method for generating ultrashort, brilliant γ-rays in compact systems, although currently these sources are still limited by low conversion efficiencies and spectral intensities. In this study, we explore laser–target driven γ-ray emission through two-dimensional (2D) and three-dimensional (3D) particle-in-cell simulations using two setups: one with a standard channel—used many times to control the laser plasma interaction—and one with a cone tapering into the channel, all using overdense walls. The cone alters the performance in three notable ways: 1) focusing the laser to a higher intensity; 2) entraining electrons from the cone walls and injecting them into the channel; 3) coupling the laser to the channel so as to alter the mode structure within the channel. Our simulations predict improved conversion efficiencies into high-energy gamma rays and greater collimation with the cone. These findings persist in 3D, where simulations reveal an ∼8-fold improvement in laser-to-photon conversion efficiency with the cone plasma setup, in comparison with the 2D cone plus channel case, corresponding with the added dimensionality of focusing. These findings suggest that the cone + channel setup can serve as an effective element at petawatt laser facilities to enable efficient γ-ray sources with broad applications.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"32 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147893540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical investigations of spatiotemporal dynamics of space-charge limited collisional sheaths","authors":"D. Vatansever, N. Nuwal, D. A. Levin","doi":"10.1063/5.0216487","DOIUrl":"https://doi.org/10.1063/5.0216487","url":null,"abstract":"Electrostatic particle-in-cell (PIC) and direct simulation Monte Carlo (DSMC) methods are used to compare the plasma dynamics of collisionless with collisional emissive sheaths in partially ionized environments. Space-charge limited emissive sheaths submersed in a plasma with a density of ∼1017 m−3 are examined using a PIC-DSMC solver, CHAOS. Collisionless emissive sheaths with plasma domains sufficiently long (30 and 60 Debye lengths, λD) are subject to strong oscillations due to two-stream electron instability, whereas emissive sheaths in weakly collisional conditions with a short domain (15 λD) exhibit self-spike (sawtooth) oscillations in the plasma field due to the trapped charge-exchange (CEX) ion population within the virtual cathode (VC) region. The two-stream electron instability leads to strong temporal fluctuations in the total emission current, with maximum deviations of 60% and 100% from the time-averaged current for the long plasma domains, whereas CEX collisions cause strong spikes in the emission current if the domain size is short. Our PIC-DSMC simulations show for the first time that the interaction of the two types of instabilities causes the strength of the self-spike to be weakened due to the strong fluctuations caused by the two-stream instability when a sufficiently long computational domain with ion-neutral collisions is employed. By conducting a two-dimensional Fast Fourier Transform (FFT) on the collisional and collisionless sheaths with long domains, we show that the transient evolution of CEX entrapment in the VC increases frequency of sheath oscillations up to two times the ion-acoustic frequencies observed in the collisionless sheath. CEX collisions weaken the VC region and result in a total emission current more than that obtained from the collisionless case for the same domain length. With a more rarefied neutral environment of 1019 m−3 in the plasma sheath, the total emission current increases only 4% in comparison with 14% for one order of magnitude denser environment, within 20 μs. In addition, the spike period is tested with different neutral temperatures and densities. While we do not observe any self-spike in the more rarefied environment, the spike period increased from 5 to 7.5 μs when the neutral temperature is increased from 300 to 2000 K in the denser environment with the simulation time of 20 μs.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"7 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259300","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toroidal Alfvén mode instability driven by plasma current in low-density Ohmic plasmas of the spherical tori","authors":"V. S. Marchenko, S. N. Reznik","doi":"10.1063/5.0223920","DOIUrl":"https://doi.org/10.1063/5.0223920","url":null,"abstract":"Due to intrinsically low magnetic fields, at low density the drift speed of the current-carrying electrons in spherical tokamaks can exceed fraction of the Alfvén speed sufficient for the excitation of the Alfvén gap modes. A particular case of the toroidal mode, observed during minor disruptions in Ohmic shots on SUNIST [Liu et al., Phys. Plasmas 23, 120706 (2016)], is considered in the present communication. Due to the negligible effect of the electron pressure gradient, the growth rate scales linearly with the drift speed, with slope inversely proportional to electron thermal velocity. In the absence of continuum damping, the threshold value of the drift speed for TAE excitation is independent of electron temperature.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"52 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of N2 admixture on mode transition of discharge in N2–Ar helicon plasma","authors":"Tianliang Zhang, Zhangyu Xia, Feng He, Bocong Zheng, Jiting Ouyang","doi":"10.1063/5.0227336","DOIUrl":"https://doi.org/10.1063/5.0227336","url":null,"abstract":"Effects of N2 admixture on multiple wave modes and transitions were investigated in N2–Ar helicon plasma under fixed input power and magnetic field. The structures of helicon waves were measured by a B-dot probe to verify the different eigenmodes. The experimental results show that the plasma morphology, emission spectrum, and spatial profile change significantly during mode transitions with the N2–Ar ratio. The calculated results from the pressure balance model indicate that the densities of species N2, N+, Ar, and Ar+ will change largely during mode transition around some specific N2 percentages, which will help to improve the application of N2–Ar helicon plasma in material processing greatly.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"55 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259326","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Design and modeling of indirectly driven magnetized implosions on the NIF","authors":"D. J. Strozzi, H. Sio, G. B. Zimmerman, J. D. Moody, C. R. Weber, B. Z. Djordjević, C. A. Walsh, B. A. Hammel, B. B. Pollock, A. Povilus, J. P. Chittenden, S. O'Neill","doi":"10.1063/5.0214674","DOIUrl":"https://doi.org/10.1063/5.0214674","url":null,"abstract":"The use of magnetic fields to improve the performance of hohlraum-driven implosions on the National Ignition Facility (NIF) is discussed. The focus is on magnetically insulated inertial confinement fusion, where the primary field effect is to reduce electron-thermal and alpha-particle loss from the compressed hotspot (magnetic pressure is of secondary importance). We summarize the requirements to achieve this state. The design of recent NIF magnetized hohlraum experiments is presented. These are close to earlier shots in the three-shock, high-adiabat (BigFoot) campaign, subject to the constraints that magnetized NIF targets must be fielded at room-temperature, and use ≲1 MJ of laser energy to avoid the risk of optics damage from stimulated Brillouin scattering. We present results from the original magnetized hohlraum platform, as well as a later variant that gives a higher hotspot temperature. In both platforms, imposed fields (at the capsule center) of up to 28 T increase the fusion yield and hotspot temperature. Integrated radiation-magneto-hydrodynamic modeling with the Lasnex code of these shots is shown, where laser power multipliers and a saturation clamp on cross-beam energy transfer are developed to match the time of peak capsule emission and the P2 Legendre moment of the hotspot x-ray image. The resulting fusion yield and ion temperature agree decently with the measured relative effects of the field, although the absolute simulated yields are higher than the data by 2.0−2.7×. The tuned parameters and yield discrepancy are comparable for experiments with and without an imposed field, indicating the model adequately captures the field effects. Self-generated and imposed fields are added sequentially to simulations of one BigFoot NIF shot to understand how they alter target dynamics.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"17 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259301","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytical model of a Hall thruster","authors":"Trevor Lafleur, Pascal Chabert","doi":"10.1063/5.0220130","DOIUrl":"https://doi.org/10.1063/5.0220130","url":null,"abstract":"Hall thrusters are one of the most successful and prevalent electric propulsion systems for spacecraft in use today. However, they are also complex devices and their unique E×B configuration makes modeling of the underlying plasma discharge challenging. In this work, a steady-state model of a Hall thruster is developed and a complete analytical solution presented that is shown to be in reasonable agreement with experimental measurements. A characterization of the discharge shows that the peak plasma density and ionization rate nearly coincide and both occur upstream of the peak electric field. The peak locations also shift as the thruster operating conditions are varied. Three key similarity parameters emerge that govern the plasma discharge and which are connected via a thruster current–voltage relation: a normalized discharge current, a normalized discharge voltage, and an amalgamated parameter, α¯, that contains all system geometric and magnetic field information. For a given normalized discharge voltage, the similarity parameter α¯ must lie within a certain range to enable high thruster performance. When applied to a krypton thruster, the model shows that both the propellant mass flow rate and the magnetic field strength must be simultaneously adjusted to achieve similar efficiency to a xenon thruster (for the same thruster geometry, discharge voltage, and power level).","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"43 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259302","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Limiting current in a collisional crossed-field gap","authors":"Lorin I. Breen, Keith L. Cartwright, Amanda M. Loveless, Allen L. Garner","doi":"10.1063/5.0223826","DOIUrl":"https://doi.org/10.1063/5.0223826","url":null,"abstract":"Crossed-field devices are often used in pulsed power and high-power microwave applications. Previous studies derived closed-form solutions for the limiting current of a vacuum crossed-field system, corresponding to the maximum permissible current for laminar flow, below and above the Hull cutoff BH for magnetic insulation. We extend these studies by introducing collision frequency into the electron force law as a friction term to derive the limiting current in a collisional crossed-field gap. The resulting solution recovers the vacuum crossed-field case in the limit of no collisions and the collisional space-charge limited current with general initial velocity for magnetic field B→0. In the limit of infinite collisions, we obtain a crossed-field equivalent to the Mott–Gurney law for the maximum current permissible in a collisional, nonmagnetic diode. When the collision frequency ν is less than the electron cyclotron frequency Ω, increasing initial velocity makes the critical current nonmonotonic with increasing ν with the critical current higher at B=BH for ν=Ω. As for a misaligned crossed-field gap where a component of the magnetic field was introduced parallel to the electric field across the gap, magnetic insulation is eliminated and the discontinuity at B=BH for limiting current observed in a vacuum crossed-field gap vanishes. As B→∞, the limiting current approaches a constant that depends on the initial velocity and the collision frequency.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"46 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259327","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Data-driven prediction of scaling and ignition of inertial confinement fusion experiments","authors":"Jim A. Gaffney, Kelli Humbird, Andrea Kritcher, Michael Kruse, Eugene Kur, Bogdan Kustowski, Ryan Nora, Brian Spears","doi":"10.1063/5.0215962","DOIUrl":"https://doi.org/10.1063/5.0215962","url":null,"abstract":"Recent advances in inertial confinement fusion (ICF) at the National Ignition Facility (NIF), including ignition and energy gain, are enabled by a close coupling between experiments and high-fidelity simulations. Neither simulations nor experiments can fully constrain the behavior of ICF implosions on their own, meaning pre- and postshot simulation studies must incorporate experimental data to be reliable. Linking past data with simulations to make predictions for upcoming designs and quantifying the uncertainty in those predictions has been an ongoing challenge in ICF research. We have developed a data-driven approach to prediction and uncertainty quantification that combines large ensembles of simulations with Bayesian inference and deep learning. The approach builds a predictive model for the statistical distribution of key performance parameters, which is jointly informed by past experiments and physics simulations. The prediction distribution captures the impact of experimental uncertainty, expert priors, design changes, and shot-to-shot variations. We have used this new capability to predict a 10× increase in ignition probability between Hybrid-E shots driven with 2.05 MJ compared to 1.9 MJ, and validated our predictions against subsequent experiments. We describe our new Bayesian postshot and prediction capabilities, discuss their application to NIF ignition and validate the results, and finally investigate the impact of data sparsity on our prediction results.","PeriodicalId":20175,"journal":{"name":"Physics of Plasmas","volume":"31 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259328","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}