Sustainment of a high-density plasma is an essential issue in fusion reactors, and penetration of particles deep into the core is necessary after injecting solid fuel pellets. One of the promising methods is to utilize a radial inward particle flux induced by plasma turbulence. In this paper, a global model is used to simulate the plasmas after post-ablation by introducing a peaked density profile as an initial condition. Nonlinearly sustained inward fluxes was observed, so nonlinear analyses are carried out to evaluate the energy balance of the fluctuation modes, which identifies dominant nonlinear couplings that drive the inward particle flux. The sustainment includes two fundamental mechanisms: (i) nonlinear mode couplings associated with local linear unstable modes and nonlinearly excited modes, and (ii) nonlocal turbulence spreading from the strong gradient region. This study provides the basis to increase an inward turbulent flux in the inverted particle gradient region.

Thanks to advances in plasma science and enabling technology, mirror machines are being reconsidered for fusion power plants and as possible fusion volumetric neutron sources. However, cross-field transport and turbulence in mirrors remains relatively understudied compared with toroidal devices. Turbulence and transport in mirror configurations were studied utilizing the flexible magnetic geometry of the Large Plasma Device (LAPD). Multiple mirror ratios from $M=1$ to $M=2.68$ and three mirror-cell lengths from $L=3.51$ to $L=10.86$ m were examined. Langmuir and magnetic probes were used to measure profiles of density, temperature, potential and magnetic field. The electric field-fluctuation-driven ${\tilde {\boldsymbol{E}}} \times {\boldsymbol{B}}$ particle flux, where $\boldsymbol{B}$ is the background field, was calculated from these quantities. Two probe correlation techniques were used to infer wavenumbers and two-dimensional structure. Cross-field particle flux and density fluctuation power decreased with increased mirror ratio. Core density and temperatures remain similar with mirror ratio, but radial line-integrated density increased. The physical expansion of the plasma in the mirror cell by using a higher field in the source region may have led to reduced density fluctuation power through the increased gradient scale length. This increased scale length reduced the growth rate and saturation level of rotational interchange and drift-like instabilities. Despite the introduction of magnetic curvature, no evidence of mirror-driven instabilities – interchange, velocity space or otherwise – were observed. For curvature-induced interchange, many possible stabilization mechanisms were present, suppressing the visibility of the instability.

Experimental analysis at DIII-D shows that small edge localized modes (ELMs) deposit a larger fraction of their energy to the first wall, compared to type-I ELMs in similar magnetic configuration and input power. The energy (λQ) and particle (λΓ) flux decay lengths in the scrape-off layer (SOL) are up to 3 and 5 times larger, respectively, for small ELMs than for larger type-I ELMs. Transport dynamics of ELM filaments in the SOL are found to be related to divertor conditions, where high divertor collisionality, typical for partially detached plasmas, is associated with increased cross field ELM radial fluxes. Results show that a sufficiently large outer wall gap and/or limiters might be needed in future scenarios to protect the first wall, if operating with small ELMs and a cold divertor. This might also have implications for RF heating in future devices, where the coupling efficiency is dependent to some degree to the outer-wall gap.

Abstract One dimensional fluid/electron Monte Carlo simulations of capacitively coupled Ar/O2 discharges driven by sawtooth up voltage waveforms are performed as a function of the number of consecutive harmonics driving frequencies of 13.56 MHz, N (1–3), pressure (200–500 mTorr) and gas mixture (10%–90% admixture of O2 to Ar). The effects of these external parameters on the electron dynamics, and the transport of ions and neutrals are revealed at constant peak-to-peak driving voltage. The electronegativity is found to decline as the number of consecutive harmonics increases and the DC self-bias voltage decreases. Increasing the pressure also leads to a decrease in electronegativity. The combination of a decrease in the mean free path of electrons and the presence of the electrical asymmetry effect result in different spatio-temporal distributions of the ionization rate, which lead to a reduction in the amplitude of the DC self-bias at higher pressure. As the admixture of electronegative O2 increases, the electronegativity is enhanced, and the discharge mode changes from an α—drift ambipolar (DA) hybrid to DA mode. This work focuses on linking these fundamental changes of the plasma physics induced by changing external parameters to process relevant charged particle and neutral fluxes to the electrodes. Particular attention is paid to O(1D) flux, because it is a precursor of deposition. In discharges driven by sawtooth up voltage waveforms, placing the substrate on the grounded electrode and increasing the number of consecutive harmonics, N, can facilitate the deposition process, since the O(1D) flux to the substrate is higher in these scenarios. Moreover, at an O2 admixture of 20%, the O(1D) flux is nearly as high as that at an O2 admixture of 90%, indicating that a higher O(1D) flux can be achieved without excessively increasing the O2 admixture.

Particle fluidization technology is often involved in biomass industrial applications. However, the utilization of biomass particles requires gas–solid flow and processes, such as heat transfer and reaction transformation. Therefore, in this paper, biomass pellets were processed into cylindrical particles and designed with five aspect ratios (AR = 0.5, 1.0, 1.5, 2.0, and 3.0). The kinetic and heat transfer characteristics of cylindrical particles with different aspect ratios in a bubbling fluidized bed were analyzed from macroscopic and microscopic perspectives using the Computational Fluid Dynamics-Discrete Element Method. The simulation results show that the higher the sphericity of cylindrical particles (AR = 1), there is obvious particle aggregation near the wall, and the higher the bed height, the more asymmetric the particle flux distribution. Increasing the gas superficial velocity helps to improve the mixing quality of the particles, convective heat transfer, particle temperature cooling rate, and uniformity of particle temperature distribution. The contact force between particles is much larger than the gas–particle interaction force, and the particle contact force is mainly concentrated on both sides of the wall. The larger the aspect ratio of cylindrical particles, the smaller and more uniformly distributed the particle contact force at the wall. Furthermore, when AR > 1, the drag force and lift force gradually increase with the increase in particle aspect ratio, the faster the particle temperature decreases, the larger the particle convective heat transfer, and the larger the standard deviation of temperature.

Spiral gravity separators are designed to separate multi-species slurry components based on differences in density and size. Previous studies [S. Lee et al., Phys. Fluids 26, 043302 (2014); D. Arnold et al., Phys. Fluids 31, 073305 (2019)] have investigated steady-state solutions for mixtures of liquids and single particle species in thin-film flows. However, these models are constrained to single-species systems and cannot describe the dynamics of multi-species separation. In contrast, our analysis extends to mixtures containing two particle species of differing densities, revealing that they undergo radial separation—an essential mechanism for practical applications in separating particles of varying densities. This work models gravity-driven bidensity slurries in a spiral trough by incorporating particle interactions, using empirically derived formulas for particle fluxes from previous bidensity studies on inclined planes [J. T. Wong and A. L. Bertozzi, Phys. D 330, 47–57 (2016)]. Specifically, we study a thin-film bidensity slurry flowing down a rectangular channel helically wound around a vertical axis. Through a thin-film approximation, we derive equilibrium profiles for the concentration of each particle species and the fluid depth. Additionally, we analyze the influence of key design parameters, such as spiral radius and channel width, on particle concentration profiles. Our findings provide valuable insights into optimizing spiral separator designs for enhanced applicability and adaptability.

ENN is planning the next generation experimental device EHL-2 with the goal to verify the thermal reaction rates of p-11B fusion, establish spherical torus/tokamak experimental scaling laws at 10’s keV ion temperature, and provide a design basis for subsequent experiments to test and realize the p-11B fusion burning plasma. Based on 0-dimensional (0-D) system design and 1.5-dimensional transport modelling analyses, the main target parameters of EHL-2 have been basically determined, including the plasma major radius, R 0, of 1.05 m, the aspect ratio, A, of 1.85, the maximum central toroidal magnetic field strength, B 0, of 3 T, and the plasma toroidal current, I p, of 3 MA. The main heating system will be the neutral beam injection at a total power of 17 MW. In addition, 6 MW of electron cyclotron resonance heating will serve as the main means of local current drive and MHD instabilities control. The physics design of EHL-2 is focused on addressing three main operating scenarios, i.e., (1) high ion temperature scenario, (2) high-performance steady-state scenario and (3) high triple product scenario. Each scenario will integrate solutions to different important issues, including equilibrium configuration, heating and current drive, confinement and transport, MHD instability, p-11B fusion reaction, plasma-wall interactions, etc. Beyond that, there are several unique and significant challenges to address, including establish a plasma with extremely high core ion temperature (T i,0 > 30 keV), and ensure a large ion-to-electron temperature ratio (T i,0/T e,0 > 2), and a boron concentration of 10%‒15% at the plasma core;realize the start-up by non-inductive current drive and the rise of MA-level plasma toroidal current. This is because the volt-seconds that the central solenoid of the ST can provide are very limited;achieve divertor heat and particle fluxes control including complete detachment under high P/R (> 20 MW/m) at relatively low electron densities. This overview will introduce the advanced progress in the physics design of EHL-2.

Abstract Molybdenum disulfide (MoS2) deposited by sputtering holds promise for applications in areas such as three-dimensional (3D)-stacked field-effect transistors (FETs) and human-interface devices. The quality of the MoS2 film is enhanced by maintaining a low particle flux with sufficient energy flux during sputtering. Furthermore, the sulfur defects in the MoS2 films were suppressed by annealing in a sulfur-vapor atmosphere, leading to an improvement in the film quality. This technology has great potential for the development of high-performance FETs based on MoS2 channels using sputtering.

In an era where Position, Navigation, and Timing (PNT) systems are integral to our technological infrastructure, the increasing prevalence of severe space weather events and the advent of deliberate disruptions such as GPS jamming and spoofing pose significant risks. These challenges are underscored by recent military operations in Ukraine, highlighting the vulnerability of Global Navigation Satellite Systems (GNSS). In response, we introduce the Cosmic Ray Navigation System (CRoNS). This innovative and resilient alternative utilizes cosmic ray showers for high-precision navigation in environments where GNSS is compromised or unavailable. CRoNS capitalizes on an economical, distributed network of compact muon/electron sensors deployed across urban landscapes and integrated into mobile devices. These sensors continuously refine the parameters of the coordinate system, ensuring that adaptive and self-improving PNT services provide a significant advantage over static GNSS. They constantly monitor particle flux from extensive air showers (EASs) triggered by the stable galactic cosmic ray (GCR) flux entering Earth's atmosphere. Robots and vehicles equipped with CRoNS can autonomously navigate surface landscapes and underground, cross-referencing measured particle densities against the continuously updated reference system.

Abstract Ocean eddies are mesoscale features that can extend > 100 km and maintain cohesiveness for months, impacting planktonic community structure and water column biogeochemical cycles. Standing stocks of protists in the water column and on sinking particles were investigated using microscopy, in situ imagery, and metabarcoding across an anticyclonic to cyclonic eddy dipole in the North Pacific Subtropical Gyre during July 2017. The water column was sampled from the surface to 500 m and particle interceptor traps were deployed at 150 m. Protistan assemblage composition varied substantially between sample type and analytical approach across the eddy dipole. Alveolates represented 63% of sequences from water samples. In contrast to water samples, rhizarian protists represented 79% of trap sequences obtained by metabarcoding of sediment trap material. Microscopy of trap material supported the important contribution of Rhizaria to sinking particles and revealed increased relative abundances of ciliates in the anticyclonic eddy and diatoms in the cyclonic eddy. In situ imagery confirmed the presence of relatively large Rhizaria that were not adequately assessed from water samples but contributed significantly to particle flux. Together, these data demonstrate differing perspectives of planktonic protistan community composition and contributions to sinking particles gained from the application of different sampling and analytic approaches. Our observations and analyses indicate a specific subset of the protistan community contributed disproportionately to organic matter downward export.

The passive sinking flux of particles, termed the biological gravitational pump (BGP), is an important component of the ocean’s biological carbon pump. In addition, carbon-rich particles are actively injected to depth through the diel vertical migration (DVM) of micronekton and mesozooplankton from the surface to the oceans’ twilight zone (200 m – 1000 m depth). This is known as the mesopelagic-migrant pump (MMP). We investigated the magnitude of the MMP at one subantarctic and two polar sites in summer by assessing particulate and dissolved carbon export below 200 m depth based on DVM and the composition of the mesopelagic community. Carbon injection potential (CIP) for the dominant taxa at each site was estimated through four pathways, i.e., excretion, respiration, fecal pellets, and carcass production. Blooms of two migratory tunicate species, the pyrosome Pyrosoma atlanticum (subantarctic) and the salp Salpa thompsoni (polar) dominated the micronekton biomass and MMP export ranged from 5.0 to 9.4 mg C m-2 d-1 across the three Southern Ocean sites. Mesozooplankton abundance was dominated by copepods, which contributed an additional 0.7 to 32.2 mg C m-2 d-1 to the MMP. Results from this summertime study suggest an increase in the relative importance of the MMP compared to the BGP south of the Polar Front, however, future work should target the seasonality of the MMP, which necessitates linking environmental drivers to micronekton and mesozooplankton community composition, life history, and DVM.

Proton-proton collisions at energy-frontier facilities produce an intense flux of high-energy light particles, including neutrinos, in the forward direction. At the LHC, these particles are currently being studied with the far-forward experiments FASER/FASERν and SND@LHC, while new dedicated experiments have been proposed in the context of a Forward Physics Facility (FPF) operating at the HL-LHC. Here we present a first quantitative exploration of the reach for neutrino, QCD, and BSM physics of far-forward experiments integrated within the proposed Future Circular Collider (FCC) project as part of its proton-proton collision program (FCC-hh) at s ≃ 100 TeV. We find that 109 electron/muon neutrinos and 107 tau neutrinos could be detected, an increase of several orders of magnitude compared to (HL-)LHC yields. We study the impact of neutrino DIS measurements at the FPF@FCC to constrain the unpolarised and spin partonic structure of the nucleon and assess their sensitivity to nuclear dynamics down to x ∼ 10−9 with neutrinos produced in proton-lead collisions. We demonstrate that the FPF@FCC could measure the neutrino charge radius for νe and νμ and reach down to five times the SM value for ντ. We fingerprint the BSM sensitivity of the FPF@FCC for a variety of models, including dark Higgs bosons, relaxion-type scenarios, quirks, and millicharged particles, finding that these experiments would be able to discover LLPs with masses as large as 50 GeV and couplings as small as 10−8, and quirks with masses up to 10 TeV. Our study highlights the remarkable opportunities made possible by integrating far-forward experiments into the FCC project, and it provides new motivation for the FPF at the HL-LHC as an essential precedent to optimize the forward physics experiments that will enable the FCC to achieve its full physics potential.

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.

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.