Abstract Hydrodynamical simulations of protoplanetary disk dynamics are useful tools for understanding the formation of planetary systems, including our own. Approximations are necessary to make these simulations computationally tractable. A common assumption when simulating dust fluids is that of a constant Stokes number, a dimensionless number that characterizes the interaction between a particle and the surrounding gas. Constant Stokes number is not a good approximation in regions of the disk where the gas density changes significantly, such as near a planet-induced gap. In this paper, we relax the assumption of a constant Stokes number in the popular FARGO3D code using semianalytic equations for the drag force on dust particles, which enables an assumption of constant particle size instead. We explore the effect this change has on disk morphology and particle fluxes across the gap for both outward- and inward-drifting particles. The assumption of constant particle size, rather than constant Stokes number, is shown to make a significant difference in some cases, emphasizing the importance of the more accurate treatment.

We present a method for generating homogeneous and tunable magnetic flux for bosonic particles in a lattice using Rydberg atoms. Our setup relies on Rydberg excitations hopping through the lattice by dipolar exchange interactions. The magnetic flux arises from complex hopping via ancilla atoms. Remarkably, the total flux within a magnetic unit cell directly depends on the ratio of the number of lattice sites to ancilla atoms, making it topologically protected to small changes in the positions of the atoms. This allows us to optimize the positions of the ancilla atoms to make the flux through the magnetic unit cell homogeneous. With this homogeneous flux, we get a topological band in the single-particle regime. In the many-body regime, we obtain indications of a bosonic fractional Chern insulator state at ν=1/2 filling. Published by the American Physical Society 2025

Abstract. Ocean alkalinity enhancement (OAE) has been proposed as a carbon dioxide removal technology (CDR), allowing for long-term storage of carbon dioxide in the ocean. By changing the carbonate speciation in seawater, OAE may potentially alter marine ecosystems with implications for the biological carbon pump. Using mesocosms in the subtropical North Atlantic, we provide first empirical insights into impacts of carbonate-based OAE on the vertical flux and attenuation of sinking particles in an oligotrophic plankton community. We enhanced total alkalinity (TA) in increments of 300 µmol kg−1, reaching up to ΔTA = 2400 µmol kg−1 compared to ambient TA. We applied a pCO2-equilibrated OAE approach; i.e., dissolved inorganic carbon (DIC) was raised simultaneously with TA to maintain seawater pCO2 in equilibrium with the atmosphere, thereby keeping perturbations of seawater carbonate chemistry moderate. The vertical flux of major elements, including carbon, nitrogen, phosphorus, and silicon, as well as their stoichiometric ratios (e.g., carbon-to-nitrogen ratios), remained unaffected over 29 d of OAE. The particle properties controlling the flux attenuation, including sinking velocities and remineralization rates, also remained unaffected by OAE. However, we observed abiotic mineral precipitation at high OAE levels (ΔTA = 1800 µmol kg−1 and higher) that resulted in a substantial increase in particulate inorganic carbon (PIC) formation. The associated consumption of alkalinity reduces the efficiency of CO2 removal and emphasizes the importance of maintaining OAE within a carefully defined operating range. Our findings suggest that carbon export by oligotrophic plankton communities is insensitive to OAE perturbations using a CO2 pre-equilibrated approach. The integrity of ecosystem services is a prerequisite for large-scale application and should be further tested across a variety of nutrient regimes and for less idealized OAE approaches.

Abstract Divertor asymmetry is a major challenge in achieving high-power, long-pulse discharges in future fusion reactors. Impurity seeding is the most common method for achieving divertor detachment in fusion devices. In this study, the SOLPS-ITER code is used to investigate the impact mechanisms of nitrogen (N) and neon (Ne) impurity seeding on the asymmetry between the inner and outer divertor in HL-2A under the attached and detached divertor conditions. Results indicate that N and Ne impurity seeding can increase asymmetry of energy and particle flux between the inner and outer targets. The trend in the energy flux ratio between the inner and outer targets is consistent with that of the particle flux ratio. Research indicates that under the attached divertor condition, the increase in energy flux asymmetry due to impurity seeding is primarily influenced by the electron temperatures between the inner and outer targets. However, when under the detached divertor condition, the increased asymmetry in energy and particle flux is primarily attributed to impurity seeding, which narrows the ion source generation in the inner divertor while broadening the ion sink region compared to the outer divertor.

Abstract Experimental measurements of plasma and neutral profiles across the pedestal are used in conjunction with 2D edge modeling to examine pedestal stiffness in Alcator C-Mod H-mode plasmas. Enhanced D α experiments on Alcator C-Mod observed pedestal degradation and loss in confinement below a critical value of net power crossing the separatrix, P net = P net crit ≈ 2.3 MW, in the absence of any external fueling. New analysis of ionization and particle flux profiles reveal saturation of the pedestal electron density, n e ped , despite continuous increases in ionization throughout the pedestal, inversely related to P net . A limit to the pedestal ∇ n e emerges as the particle flux, Γ D , continues to grow, implying increases in the effective particle diffusivity, D eff . This is well-correlated with the separatrix collisionality, ν sep ∗ and a turbulence control parameter, α t , implying a possible transition in type of turbulence. The transition is well correlated with the experimentally observed value of P net crit . SOLPS-ITER modeling is performed for select discharges from the power scan, constrained with experimental electron and neutral densities, measured at the outer midplane. The modeling confirms general growth in D eff , consistent with experimental findings, and additionally suggests even larger growth in χ e at the same P net crit .

A rapid increase in the use of proton therapy for cancer treatment has been seen in the last decade due to its clinical advantages. Therefore, more and more patients with implants and other metallic devices will be among those who will be treated. This study experimentally examines the effect and changes in the delivered fields, using water-equivalent phantoms with and without titanium (Ti) dental implants positioned along the primary beam path. We measured in detail the composition and spectral-tracking characterization of particles generated in the plateau region of the Bragg curve towards the Sub-peak region using high-spatial resolution, spectral and time-sensitive imaging detectors with a pixelated array provided by the ASIC chip Timepix3. A 170 MeV proton beam was collimated and modulated in a polymethyl methacrylate (PMMA) block. Placing two dental implants behind the PMMA block, the radiation was measured using two pixeled detectors with silicon (Si) sensors. The Timepix3 (TPX3) detectors measured in detail particle fluxes, dose rates (DR) and linear energy transfer (LET) spectra for resolved particle types. Artificial intelligence (AI) based-trained neural networks (NN) calibrated in well-defined radiation fields were used to analyze and identify particles based on morphology and characteristic spectral-tracking response. The beam was characterized and single-particle tracks were registered and decomposed into particle-type groups. The resulting particle fluxes in both setups are resolved into three main classes of particles: i) protons, ii) electrons and photons, and iii) ions. Protons are the main particle component responsible for dose deposition. High-energy transfer particles (HETP), namely ions exhibited differences in both dosimetric aspects that were investigated: DR and particle fluxes, when the Ti implants were placed in the setup. The detailed multi-parametric information of the secondary radiation field provides a comprehensive understanding of the impact of Ti materials in proton therapy.

Proposals for a new approach to the development of scientific equipment for the study of galactic and solar cosmic ray fluxes in the solar modulation energy range (30–1000 MeV/nucleon) with elementary charge and mass resolution are considered. It is proposed to place the equipment on the Russian space station ROS (project "Modulation") and on the international scientific lunar station MNLS (project "Moon–Modulation"), if it is created. The projects assume the creation of a database of galactic and solar cosmic rays (SCR) for the entire solar activity cycle. Such a database is necessary to improve numerical models of the fluxes of energetic heliospheric particles in interplanetary and near-Earth space.

The electrostatic accelerator (ESA) EG-5 has been operating stationary in the Nuclear Physics Department of the Nuclear Physics Department of JINR (Dubna) since 1965. Along with an experimental nuclear reactor and a pulsed accelerator IREN, ESA EG-5 occupies its own unique niche as part of a complex of nuclear physics installations. The beams of high-energy particles obtained using EG-5 have the highest energy stability (± 15 keV per 2 MeV), due to which it is possible to conduct unique studies of the elemental composition of solids, including depth profiling, conducting studies of fast neutron nuclear reactions, etc. ESA EG-5 is a universal research device that allows conducting both studies of the elemental composition and physical, chemical and biological modification of objects of inanimate and living nature, respectively. EG-5 electrostatic accelerator at FLNP JINR, used to produce intense fluxes of fast particles (H+, He+, D+) and neutrons; for elemental analysis of surface layers of various objects using beams of α-particles, using non-destructive techniques RBS, ERD and PIXE; for implantation of ions into the surface layers of various materials; to study the radiation resistance of materials. Unique opportunities will appear after the implementation of a microbeam spectrometer at the EG-5 accelerator in period since 2025.

Infections in infants, after childbirth, remain a leading cause of neonatal morbidity and mortality, globally. A soaring percentage of these infections arise from bacterial colonization of the umbilicus. Current therapy for omphalitis includes the topical application of chlorhexidine on the umbilicus. Bacteria such as Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus, which are the key causative organisms of omphalitis, are resistant to chlorhexidine. In this study, curcumin-loaded liposomes were prepared using the "thin film hydration" method. Liposomes were characterized by particle size analysis, light microscopy, encapsulation efficiency, and flux. Stable organogels were formed via a high-speed homogenization method and stabilized by an emulsifier mix. They were evaluated for stability over a period by observing for phase separation. Four gels F1 (curcumin-loaded liposomes in chlorhexidine organogel), F2 (curcumin-loaded liposomes in organogel), F3 (chlorhexidine in organogel), and control (plain organogel) were prepared. Physicochemical properties of all gels were evaluated such as organoleptic tests, gel-to-sol transition, rheological studies, pH, skin irritancy, spreadability, accelerated stability, and antibacterial activity studies. Liposomes were spherical with an average size of 7 μm and an encapsulation efficiency of 97%. The in vitro release profile best fits the Higuchi mathematical model implying that curcumin release was by diffusion and dissolution mechanism. In vitro release was also higher at pH 5.5. F1 had the highest spreadability of 63 mm2g-1 and the lowest viscosity of 184,400 MPas at a shear rate of 10 rotations per minute with a pH of 6.5. Formulation F1 also displayed the highest antibacterial activity against all three bacteria. It can be concluded that the synergistic interaction between curcumin and chlorhexidine may be responsible for the significant antibacterial potency exhibited in formulation F1. Curcumin-loaded liposomes in chlorhexidine organogel (F1) can serve as a prototype for the development of an antibacterial topical formulation having intrinsic activity and enhanced potency to combat omphalitis.

The paper studies various characteristics of solar flares and coronal mass ejections that led or did not lead to the registration of solar proton events near the Earth for the period from 1996 to 2023. A detailed catalog of events was compiled, regression dependences of the parameters of solar sources and proton flux enhancements near the Earth were obtained. A new “proton index” of the event was proposed, and calculations were made of the probability of solar proton events and expected fluxes of particles with different energies. Longitudinal distributions of various parameters characterizing proton ux enhancements were also obtained. The established patterns will form the basis of an empirical model that allows estimating the probability of high-energy particle arrival at the Earth and the expected levels and times of registering the maxima of increases in fluxes of protons with energies >10 and >100 MeV.

The fast solar wind stream which resulted from the helio-meridional crossing of an equatorial coronal hole on June 29th and 30th 2005 passed the Wind and Advanced Composition Explorer (ACE) spacecraft during July 1st and 2nd. This fast stream caused a moderate magnetospheric storm following a weak (though clearly defined) sudden commencement at 14:12 UT on July 1st. During the event, the two spacecraft were both in the vicinity of the L1 libration point, though separated in the Sun-Earth direction by about 150000 km. An algebraic method is described whereby the speed of the particle flux can be determined using measurements of the interplanetary magnetic field at the two spacecraft.

Abstract Most oceanic lead (Pb) is from anthropogenic emissions into the atmosphere deposited into surface waters, mostly during the past two centuries. The space‐ and time‐dependent emission patterns of anthropogenic Pb (and its isotope ratios) constitute a global geochemical experiment providing information on advective, mixing, chemical, and particle flux processes redistributing Pb within the ocean. Pb shares aspects of its behavior with other elements, for example, atmospheric input, dust solubilization, biological uptake, and reversible exchange between dissolved and adsorbed Pb on sinking particles. The evolving distributions allow us to see signals hidden in steady‐state tracer distributions. The global anthropogenic Pb emission experiment serves as a tool to understand oceanic trace element dynamics. We obtained a high‐resolution (5° station spacing) depth transect of dissolved Pb concentrations and Pb isotopes from Alaska (55°N) to just north of Tahiti (20°S) near 152°W longitude. The sections reveal distinct sources of Pb (American, Australian, and Chinese), transport of Australian style Pb to the water mass formation region of Sub‐Antarctic Mode Water which is advected northward, columnar Pb isotope contours due to reversible particle exchange on sinking particles from high‐productivity particle veils, and a gradient of high northern deep water [Pb] to low southern deep water [Pb] that is created by reversible exchange release of Pb from sinking particles carrying predominantly northern hemisphere Pb. 208Pb/206Pb versus 206Pb/207Pb isotope relationships show that most oceanic Pb in the North Pacific is from Chinese and American sources, whereas Pb in the South Pacific is from Australian and American sources.

The results of a comparative analysis of the solar proton event on March 30, 2022, which has an unusual time profile of solar proton fluxes, with the previous and subsequent solar proton events (March 28, 2022 and April 02, 2022) are presented. Increases in energetic proton fluxes in interplanetary and near-Earth space are associated with successive solar X-ray flares M4.0, X1.3 and M3.9 and three halo-type coronal mass ejections. The work was done based on experimental data obtained from spacecraft located in interplanetary space (ACE, WIND, STEREO A, DSCOVR), in a circular polar orbit at an altitude of 850 km (Meteor-M2) and in geostationary orbit (GOES-16, Electro-L2). An explanation has been proposed for the features of the energetic proton flux profile in the solar proton event on March 30, 2022: protons accelerated in the flare on March 30, 2022 were partially screened by an interplanetary coronal mass ejection, the source of which was the explosive processes on the Sun on March 28, 2022; late registration of maximum proton fluxes, simultaneous for particles of different energies, is due to the arrival of particle fluxes inside an interplanetary coronal mass ejection. The spatial distribution of solar protons in near-Earth orbit was similar to the distribution at the Lagrange point L1, but with a delay of ~50 min.

In tokamaks, it is commonly observed that the application of resonant magnetic perturbations (RMPs) leads to a reduction in plasma density. In this study, we show that this decrease in density is accompanied by kink-like modes in the plasma edge region in KSTAR. The dynamics of these modes is observed in the toroidal and poloidal directions using multiple diagnostics. It is captured that the phase of the edge kink-like modes aligns with the phase of the applied RMPs. In particular, a nonuniform plasma surface displacement due to these modes is measured along the poloidal direction using a novel image processing technique on in-vessel TV data. The symmetry-breaking effect of the displacement is known to be much larger than that of the applied RMPs. Thus, the modification in the magnetic field strength B on the distorted surface due to the displacement can lead to significant enhancement of the neoclassical particle transport. In this study, we calculate the enhanced neoclassical electron particle flux using the experimentally estimated variation of B in the presence of the edge kink-like modes. Transport analysis shows that the enhanced particle transport caused by the broken symmetry in the presence of the edge kink-like modes can account for a significant portion of the observed density pump-out by RMPs.

The effect of sawteeth on plasma performance and transport in the plasma of tokamak is an important problem in the fusion field. Sawtooth oscillations can trigger off heat and turbulence pulses that propagate into the edge plasma, and thus enhancing the edge shear flow and inducing a transition from low confinement mode to high confinement mode. The influences of turbulence spreading and symmetry breaking on edge shear flow with sawtooth crashes are observed in the J-TEXT tokamak. The edge plasma turbulence and shear flow are measured using a fast reciprocating electrostatic probe array. The experimental data are analyzed using some methods such as conditional average and probability distribution function. After sawtooth crashes, the heat and turbulence pulses in the core propagate to the edge, with the turbulence pulse being faster than the heat pulse. The attached figures (a)–(e) show the core electron temperature, and the edge electron temperature, turbulence intensity, turbulence drive and spreading rates, Reynolds stress and its gradient, and shearing rates, respectively. After sawtooth crashes, the edge electron temperature increases and the edge turbulence is enhanced, with turbulence preceding temperature. The enhanced edge turbulence is mainly composed of two parts: the turbulence driven by local gradient and the turbulence spreading from core to edge. The development of the estimated turbulence spreading rate is prior to that of the turbulence driving rate. The increase in the turbulence intensity can cause the turbulent Reynold stress and its gradient to increase, thereby enhancing shear flows and radial electric fields. Turbulence spreading leads the edge Reynolds stresses to develop and the shear flow to be faster than edge electron temperature. The Reynolds stress arises from the symmetry breaking of the turbulence wave number spectrum. After sawtooth collapses, the joint probability density function of radial wave number and poloidal wave number of turbulence intensity becomes highly skewed and anisotropic, exhibiting strong asymmetry, which can be seen in attached figures (f) and (g). The development of turbulence spreading flux at the edge is also prior to the particle flux driven by turbulence, indicating that turbulent energy transport is not simply accompanied by turbulent particle transport. These results show that the turbulence spreading and symmetry breaking can enhance turbulent Reynolds stress, thereby driving shear flows, after sawtooth has crashed.

A porous conical type electrospray array thruster consisting of 6102 individual emitters is operated at up to 13.3 W power. The design and manufacture of the thruster are described, including its porous glass emitter chip and metallized ceramic extractor chip. A precision mass balance mounted inside a bell jar is used to directly measure the thrust, specific impulse, and efficiency in negative polarity, from 42±0.5μN, 1050±26 s, and 57±1.9% at -1000 V and 0.38 W to 174±0.5μN, 420±2 s, and 21±0.3% at -1300 V and 1.7 W. Additional negative polarity experiments in a 2 meter vacuum facility demonstrate powers from order 1 μW to over 10 W, spanning 7 orders of magnitude. Power and performance measurements were not repeated for positive mode operation, as this was found to induce arcing between the emitter and extractor electrodes at 1400 V and above. The drop in efficiency from -1000 V to -1300 V operation in the bell jar is discussed within the context of facility effects, and secondary charged particle flux to the thruster is identified as a likely contributor. Finally, the performance of the thruster is considered relative to scaling electrospray systems to higher power robustly.

The neutron radiation of the lunar surface under the influence of energetic charged particle flux from the intense Solar Proton Event (SPE) is considered. Numerical estimates of the neutron flux and the corresponding neutron component of the radiation dose are made for the historical Carrington SPE, which can be considered an example of the most intense SPE recorded in the modern period of solar activity observations. It is shown that the neutron component of the dose during the Carrington SPE was approximately 1000 times higher than the background value from the impact of Galactic cosmic rays (GCR) on the lunar surface under quiet Sun conditions. The value of the total radiation dose on the lunar surface during the Carrington SPE was close to the limit values for humans in space.

Studying the auroral emissions is of great importance since they are created in an atmospheric layer (80–300 km) where in-situ measurements are complicated and they represent a good proxy of the particle precipitations into the atmosphere. The emission spectrum of the aurora is complex, made of both atomic and molecular lines. The intensities of these emissions vary with the solar and geomagnetic activities, mostly due to the particle precipitations. In this paper, we simulate auroral emission spectra for a given distribution of precipitating electrons using Transsolo, a kinetic code solving the transport equation of the electrons along the local magnetic field line. It allows calculations of the particle fluxes for different energies, pitch-angles and altitudes, from which the related emissions are computed. The modules to compute the emissions have recently been updated by including the vibrational structures of the molecular bands and several atomic lines. Only the O2 emissions and the hydrogen emissions due to proton precipitations are not considered in the model. The code also permits to relate auroral spectra with characteristics of the precipitating electrons such as their mean energy and total fluxes at the top of the atmosphere. Such simulations also provide the auroral spectrum at any altitude of the upper atmosphere, which is important in the perspective of volume emission reconstructions as done using tomographic-like techniques. Moreover, many auroral monitoring instruments are equipped with filters of variable widths. Such synthetic spectra can help to identify possible contamination of the measurements due to overlap of several emission lines. For example, the green line at 557.7 nm overlaps with several O2+, N I and N2 lines or bands in a ±5 nm range. Calculating the relative ratio of these lines in different conditions is therefore crucial for measurements using a filter of 5 nm width. For example, we discuss if these overlapped lines could possibly be at the origin of the linear polarization measured in the green line despite the fact that the theory of impact polarization predicts zero polarization.

The transition between two-dimensional hydrodynamic turbulence and quasi-one-dimensional zonostrophic turbulence is examined in the modified Hasegawa–Wakatani system, which is considered as a minimal model of β-plane-like drift-wave turbulence with an intrinsic instability. Extensive parameter scans were performed across a wide range of values for the adiabaticity parameter C describing the strength of coupling between the two equations. A sharp transition from 2D isotropic turbulence to a quasi-1D system, dominated by zonal flows, is observed using the fraction of the kinetic energy of the zonal modes as the order parameter, at C≈0.1. It is shown that this transition exhibits a hysteresis loop around the transition point, where the adiabaticity parameter plays the role of the control parameter of its nonlinear self-organization. It was also observed that the radial particle flux scales with the adiabaticity parameter following two different power law dependencies in the two regimes. A simple quasi-linear saturation rule which accounts for the presence of zonal flows is proposed, and is shown to agree very well with the observed nonlinear fluxes. Motivated by the phenomenon of quasi-one dimensionalisation of the system at high C, a number of reduction schemes based on a limited number of modes were investigated and the results were compared to direct numerical simulations. In particular, it was observed that a minimal reduced model consisting of 2 poloidal and 2 radial modes was able to replicate the phase transition behavior, while any further reduction failed to capture it.

During the EAST radiative divertor experiments, one of the key challenges was how to avoid the occurrence of disruptive events caused by excessive impurity seeding. To estimate the required impurity fraction for divertor detachment, we introduce a reduced edge plasma radiation model. In the model, based on the momentum conservation along the magnetic field line, the upstream pressure is determined by the plasma density and temperature at the divertor target, and then the impurity radiation loss is obtained by the balance of the heat and particle fluxes. It is found that the required impurity fraction shows a non-monotonic variation with divertor electron temperature ( ) when . In the range of , the position near the valley of required impurity fraction corresponds to strong plasma recombination. Due to the dependence of the volumetric momentum loss effect on the in the range of , the required impurity fraction peaks and then decreases as is increased. Compared to neon, the usage of argon reduces the impurity fraction by about twice. In addition, for the various fitting parameters in the pressure–momentum loss model, it is shown that the tendency of required impurity fraction with always increases first and then decreases in the range of , but the required impurity fraction decreases when the model that characterizes the strong loss in pressure momentum is used.