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Plasma-based water purification involves the transport of reactive species across the gas–liquid interface. This process is limited by slow diffusion driven mass transport of reactive species across the interface. Additionally, the plasma gas–liquid contact area is typically limited, contributing to reduced dose delivery. These key factors make it difficult to scale up the treatment process to input flows of industrial interest. In this work, turbulence is explored as a means to introduce a fine grain structure, thus greatly increasing the interfacial surface area, leading to large property gradients and more efficient mass transport. Such a fine scale structure can also enhance the local electric field. The test apparatus explored in this work is the packed bed reactor that places thin water jets into contact with plasma. It is theorized that introducing turbulence, via increasing Reynolds number in such thin jets, may enhance the effective plasma dose at fixed plasma power. In this work, changes in the flow regime, from laminar to turbulent, of water jets in a packed bed water reactor (PBR) configuration are investigated experimentally. Methylene blue dye, a model contaminant, was tested in the PBR to demonstrate enhanced treatment via reduced treatment times. Plasma surface morphology around the jets noticeably changed with the flow regime, and turbulent flow demonstrated a faster hydrogen peroxide uptake, along with slower temperature, electrical conductivity, and a pH change in a batch treatment process, compared to laminar flow. The dye was destroyed significantly faster in the turbulent flow, indicating an increased effective plasma dose. 

Stratospheric aerosol injection (SAI) of reflective sulfate aerosols has been proposed to temporarily reduce the impacts of global warming. In this study, we compare two SAI simulations which inject at different altitudes to provide the same amount of cooling, finding that lower‐altitude SAI requires 64% more injection. SAI at higher altitudes cools the surface more efficiently per unit injection than lower‐altitude SAI through two primary mechanisms: the longer lifetimes of SO₂and SO₄at higher altitudes, and the water vapor feedback, in which lower‐altitude SAI causes more heating in the tropical cold point tropopause region, thereby increasing water vapor transport into the stratosphere and trapping more terrestrial infrared radiation that offsets some of the direct aerosol‐induced cooling. We isolate these individual mechanisms and find that the contribution of lifetime effects to differences in cooling efficiency is approximately five to six times larger than the contribution of the water vapor feedback.

 

Abstract The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation 1,2 . Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole 3 . Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of $${8.4}_{-1.1}^{+0.5}$$ 8.4 − 1.1 + 0.5 Schwarzschild radii in diameter, approximately 50% larger than that seen at 1.3 mm. The outer edge at 3.5 mm is also larger than that at 1.3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects, in addition to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow. 

We investigate an interval of moderate magnetic activity from 0–8 UT on 14 March 2008 by using a global magnetohydrodynamics (MHD) simulation with high spatial and temporal resolution. Observations show several distinct substorms during this interval. One of these with onset at 04:44 UT occurs at 04:42 UT in the simulation. The simulation shows reconnection is continuously present at multiple sites. During the growth phase, the number of X‐lines decreases as their total length increase and their locations approach the Earth. The X‐lines create multiple fast flow channels with dipolarization fronts. The total length and area of these channels increase during the growth phase as they penetrate closer to the Earth carrying more magnetic flux. The 04:42 UT onset in the simulation was preceded by the growth of an X‐line that eventually extended 55R_Efrom 12R_Epremidnight to 50 on the dawn side. It produced a narrow flow channel parallel to the X‐line that eventually penetrated inside 10R_Erapidly depositing magnetic flux as the expansion phase developed. Despite this good agreement in expansion phase onset time, ground and satellite observations suggest a quiet growth phase with a sudden onset of reconnection. It may be possible to explain the difference between observations and simulations if all growth phase activity in the simulation maps to the ionosphere at very high latitudes. An auroral streamer at onset maps in the simulation very close to Earth. A recovery phase streamer maps to the middle tail.

 

A search for pair production of squarks or gluinos decaying via sleptons or weak bosons is reported. The search targets a final state with exactly two leptons with same-sign electric charge or at least three leptons without any charge requirement. The analysed data set corresponds to an integrated luminosity of 139 fb⁻¹of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Multiple signal regions are defined, targeting several SUSY simplified models yielding the desired final states. A single control region is used to constrain the normalisation of theWZ+ jets background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of several supersymmetric models featuring R-parity conservation or R-parity violation, yielding exclusion limits surpassing those from previous searches. In models considering gluino (squark) pair production, gluino (squark) masses up to 2.2 (1.7) TeV are excluded at 95% confidence level.

 

We investigate the relation of fast flows at the inner edge of the plasma sheet to the onset of auroral expansion. Recent work suggests that nearly all expansions are an instability triggered by an auroral streamer from far out in the magnetotail. We investigate an 8‐hr interval of activity on 14 March 2008 using ground magnetometer and all‐sky camera data to determine the onset times of six substorm expansions. We compare these times with Time History of Events and Macroscale Interactions during Substorms observations of plasma flow and magnetic field. We show that every expansion followed the arrival of a fast flow and dipolarization event at the inner edge of the plasma sheet. To relate the aurora to flows, we develop procedures for removing fixed lights, the moving Moon and its reflection, and contamination due to scattered moonlight. We scan movies of enhanced images for auroral streamers. Three onsets were tentatively associated with streamers. For two, the apparent source was very close to the growth phase arc mapping close to Earth. For one, an onset occurred in the recovery phase of an earlier substorm after a double oval had formed. For this one, the end of an N‐S streamer stopped about 2° north of the breakup arc. For the remaining three expansions, no streamers were associated with the onsets. Most substorms exhibit N‐S streamers in the recovery phase. These usually cannot be associated with fast flows. Either fast flows in the growth phase do not produce streamers or they make streamers that require significant image enhancement.

 

A search for supersymmetry targeting the direct production of winos and higgsinos is conducted in final states with either two leptons (eorμ) with the same electric charge, or three leptons. The analysis uses 139 fb⁻¹ofppcollision data at$$ \sqrt{s} $$$\sqrt{s}$= 13 TeV collected with the ATLAS detector during Run 2 of the Large Hadron Collider. No significant excess over the Standard Model expectation is observed. Simplified and complete models with and withoutR-parity conservation are considered. In topologies with intermediate states including eitherWhorWZpairs, wino masses up to 525 GeV and 250 GeV are excluded, respectively, for a bino of vanishing mass. Higgsino masses smaller than 440 GeV are excluded in a naturalR-parity-violating model with bilinear terms. Upper limits on the production cross section of generic events beyond the Standard Model as low as 40 ab are obtained in signal regions optimised for these models and also for anR-parity-violating scenario with baryon-number-violating higgsino decays into top quarks and jets. The analysis significantly improves sensitivity to supersymmetric models and other processes beyond the Standard Model that may contribute to the considered final states.

 

Search for a new pseudoscalar a-boson decaying to muons in events with additional top quark pairs. 

Abstract The Phase-I trigger readout electronics upgrade of the ATLAS Liquid Argon calorimeters enhances thephysics reach of the experiment during the upcoming operation atincreasing Large Hadron Collider luminosities.The new system, installed during the second Large Hadron Collider Long Shutdown,increases the trigger readout granularity by up to a factor of tenas well as its precision and range.Consequently, the background rejection at trigger level is improvedthrough enhanced filtering algorithms utilizing the additional informationfor topological discrimination of electromagnetic and hadronic shower shapes.This paper presents the final designs of the new electronic elements,their custom electronic devices, the proceduresused to validate their proper functioning, and the performance achievedduring the commissioning of this system.