Plasma Distribution Research Articles

Reconstruction of Fermi and eROSITA Bubbles from Magnetized Jet Eruption with Simulations

The Fermi bubbles and the eROSITA bubbles around the Milky Way Galaxy are speculated to be the aftermaths of past jet eruptions from a supermassive black hole in the galactic center. In this work, a 2.5D axisymmetric relativistic magnetohydrodynamic (RMHD) model is applied to simulate a jet eruption from our galactic center and to reconstruct the observed Fermi bubbles and eROSITA bubbles. High-energy non-thermal electrons are excited around forward shock and discontinuity transition regions in the simulated plasma distributions. The γ-ray and X-ray emissions from these electrons manifest patterns on the skymap that match the observed Fermi bubbles and eROSITA bubbles, respectively, in shape, size and radiation intensity. The influence of the background magnetic field, initial mass distribution in the Galaxy, and the jet parameters on the plasma distributions and hence these bubbles is analyzed. Subtle effects on the evolution of plasma distributions attributed to the adoption of a galactic disk model versus a spiral-arm model are also studied.

Prediction of plasma path and analysis of axial fracturing properties in rock fragmentation by high-voltage pulsed discharge (RHPD)

Rock fragmentation by high-voltage pulsed discharge (RHPD) is widely utilized in resource recovery and energy extraction due to its low energy consumption and high efficiency. However, observing the plasma development process during RHPD presents challenges, and the frequency dependence of dielectric properties further complicates plasma path prediction and the analysis of fracturing properties in the axial direction of the plasma. To address these issues, we analyzed the development properties of plasma within rocks and established a segmented breakdown criterion that considered the propagation velocity of plasma. Additionally, utilizing a transient electromagnetic field model and a particle flow model (PFM), we established a multi-physics field model and proposed a predictive method for the plasma path in a rock–liquid combination environment. This allows for the quantification of the velocity, potential, and length of the plasma. Furthermore, we computed the time response of shock waves and analyzed the loading mechanism of shock waves. Based on the spatial distribution of plasma, the PFM was applied to simulate the fracturing properties of rocks under shock wave loading. Finally, we established a comprehensive experimental platform for RHPD and conducted three-dimensional reconstructions of the fractured area to validate the accuracy of plasma path prediction methods and fracturing properties analysis. This study significantly advances plasma development theory and provides insights for optimizing rock fragmentation efficiency.

Numerical and experimental study of supersonically expanding argon plasma using a micrometer hollow cathode discharge

Pulsed discharge nozzles (PDNs) have been successfully used for decades to produce rotationally cold (Trot ∼ 20 K) radicals and ions of astrophysical interest and to characterize these species spectroscopically. In this work, an evolution of the PDN, the piezostack pulsed discharge nozzle (P2DN), is used for the first time to investigate the characteristics of the still poorly understood supersonic plasma expansion. The P2DN allows for a better control of the reservoir pressure of which an accurate measurement is required to characterize the plasma expansion. This new source, thus, gives the opportunity to further optimize the plasma conditions and extend its use to new target species. The spatial distribution of an argon plasma and the effect of the supersonic flow for different pressures are studied by combining a two-dimensional extended fluid model (extFM) and a direct simulation Monte Carlo (DSMC) method. The combined simulation is validated with experimental results obtained through emission spectroscopy associated with a group-code collisional-radiative model to retrieve the plasma parameters. The validated numerical approach (DSMC-extFM) allows for an accurate characterization of the plasma structure in our typical experimental conditions (a reservoir pressure ranging from 90 to 905 mbar). Thus, this simulation will be used in future studies to improve the plasma conditions to favor the synthesis of (transient) hydrocarbon species as found in space, by seeding the argon gas with a suitable precursor, such as acetylene.

Effect of coil and chamber structure on plasma radial uniformity in radio frequency inductively coupled plasma

Enhancing plasma uniformity can be achieved by modifying coil and chamber structures in radio frequency inductively coupled plasma (ICP) to meet the demand for large-area and uniformly distributed plasma in industrial manufacturing. This study utilized a two-dimensional self-consistent fluid model to investigate how different coil configurations and chamber aspect ratios affect the radial uniformity of plasma in radio frequency ICP. The findings indicate that optimizing the radial spacing of the coil enhances plasma uniformity but with a reduction in electron density. Furthermore, optimizing the coil within the ICP reactor, using the interior point method in the Interior Point Optimizer significantly enhances plasma uniformity, elevating it from 56% to 96% within the range of the model sizes. Additionally, when the chamber aspect ratio k changes from 2.8 to 4.7, the plasma distribution changes from a center-high to a saddle-shaped distribution. Moreover, the plasma uniformity becomes worse. Finally, adjusting process parameters, such as increasing source power and gas pressure, can enhance plasma uniformity. These findings contribute to optimizing the etching process by improving plasma radial uniformity.

The multi-peak point phenomenon of broadband microwave reflection caused by inhomogeneous plasma

During spacecraft re-entry, the challenge of measuring plasma sheath parameters directly contributes to difficulties in addressing communication blackout. In this work, we have discovered a phenomenon of multiple peaks in reflection data caused by the inhomogeneous plasma. Simulation results show that the multi-peak points fade away as the characteristic frequency is approached, resembling a series of gradually decreasing peaks. The positions and quantities of these points are positively correlated with electron density, yet they show no relation to collision frequency. This phenomenon is of significant reference value for future studies on the spatial distribution of plasmas, particularly for using microwave reflection signals in diagnosing the plasma sheath.

Tomographic reconstructions of the fast-ion phase space using imaging neutral particle analyser measurements

In this paper we demonstrate how the inversion, in energy and major radius (E, R) coordinates, of imaging neutral particle analyser (INPA) measurements can be used to obtain the fast-ion distribution. The INPA is most sensitive to passing ions with energies in the range (20–150) keV and pitches near 0.5 in the core and 0.7 near the plasma edge. Inversion of synthetic signals, via 0th-order Tikhonov and Elastic Net regularization, were performed to demonstrate the capability of recovering the ground truth fast-ion 2D phase-space distribution resolved in major radius and energy, even in the presence of moderate noise levels (10%). Finally, we apply our method to measure the 2D phase-space distribution in an MHD quiescent plasma at ASDEX Upgrade and find good agreement with the slowing down fast-ion distribution predicted by TRANSP.

Examination of Magnetic Field Signatures and Local Plasma Distribution Variations in Jupiter's Magnetosphere

AbstractSpinning disk of plasma results in deformation of Jupiter's magnetic field from a dipole to a magnetodisc configuration with significant radial and azimuthal components. Polar orbit of the Juno spacecraft enables a comprehensive in situ observation of Jupiter's plasmadisc at different latitudes. Observations from magnetometer and plasma distribution instruments on Juno mission were used to examine interaction of magnetic field and heavy ions in Jupiter's nightside magnetosphere. Power spectrum analysis was used to evaluate magnetic fluctuations inside and outside of the plasmadisc. Extensive radial maps of magnetic activity in Jupiter's nightside magnetosphere are presented. Comprehensive examination of magnetic fluctuations enable to identify local plasma density variations that correlate with plasma distribution count rate fluctuations. Observations of magnetic signatures together with examination of plasma distribution are used to detect features that point to plasma transport inside and outside of Jupiter's plasmadisc. This work shows that plasma in Jupiter's magnetosphere is contained near centrifugal equator and is not a subject to curvature drift that could generate ring currents. Signatures described as current sheet crossings were investigated. On close inspection these signatures show attributes that belong to stand alone formations rather than a single current sheet structure. This work shows that current flow is not an adequate mechanism to explain deformation of Jupiter's magnetic field.

Influence of plasma on the optical appearance of spinning black hole in Kalb-Ramond gravity and its Existence around M87* and Sgr A*

The visible universe is filled with different types of plasma media in the form of stars, nebulas and other forms of excited gases. These matter fields have a high influence on the gravity and are likely to be present around the black holes due to the immense gravitational attraction. Since a plasma medium affects the speed of light, therefore we investigated the null geodesics and various optical features around the rotating black hole in Kalb-Ramond gravity immersed in plasma medium. Various plasma distributions are considered to develop a comparative study for their influence on unstable null circular orbits, shadows and evaporation rate of the black hole in the presence of a plasma medium. Moreover, the shadow results are also compared with Event Horizon Telescope data for M78* and Sgr A* in order to estimate the parametric bounds for which the rotating black hole in Kalb-Ramond gravity is considered either M87* or Sgr A* under the different values of plasma parameters. From this analysis, we also found the distribution of plasma that has a significant impact on the above mentioned features and is most likely to be present around M87* and Sgr A*.

Design and Experiment of a Slotted Antenna Surface Wave Plasma Flood Gun

In a modern ion implanter, plasma flood gun (PFG) is used to neutralize wafer charge during doping process, preventing the breakdown of floating wafers caused by the space charge accumulation. In order to obtain the PFG which can produce ribbon electron beams with the characteristics of high stability, high plasma density, no metal pollution and long life, studies at Peking University (PKU) are focused on surface wave plasma flood gun (SW-PFG) recently. A 2.45 GHz SW-PFG with a quartz plate and a series of metal slotted antenna arrays was designed and tested. Theoretical studies are carried out to optimize the SW-PFG structural parameters. The quartz plate thickness is determined as 15 mm. The size of the plasma chamber is 280 mm×150 mm×40 mm with a 280 mm×2 mm extraction slit. In the experiment, a relatively uniform argon plasma is obtained under the condition of gas flow rate of 2 sccm and input power of 800 W. In this case, the plasma distribution is studied by emission spectrum diagnosis and 73 mA ribbon electron beam is measured.

Thermal Evolution of an Active Region Through Quiet and Flaring Phases as Observed by NuSTAR, XRT, and AIA

Solar active regions (ARs) contain a broad range of temperatures, with the thermal plasma distribution often observed to peak in the few millions of kelvin. Differential emission measure (DEM) analysis can allow instruments with diverse temperature responses to be used in concert to estimate this distribution. Nuclear Spectroscopic Telescope ARray (NuSTAR) hard X-ray (HXR) observations are uniquely sensitive to the highest-temperature components of the corona, and thus extremely powerful for examining signatures of reconnection-driven heating. Here, we use NuSTAR diagnostics in combination with extreme-ultraviolet and soft X-ray observations (from the Solar Dynamics Observatory/Atmospheric Imaging Assembly and Hinode/X-Ray Telescope) to construct DEMs over 170 distinct time intervals during a 5 hr observation of an alternately flaring and quiet active region (NOAA designation AR 12712). This represents the first HXR study to examine the time evolution of the distribution of thermal plasma in an AR. During microflares, we find that the initial microflare-associated plasma heating is predominantly heating of material that is already relatively hot, followed later on by broader heating of initially cooler material. During quiescent times, we show that the amount of extremely hot (>10 MK) material in this region is significantly (∼2–4 orders of magnitude) less than that found in the quiescent AR observed in HXRs by FOXSI-2. This result implies there can be radically different high-temperature thermal distributions in different ARs, and strongly motivates future HXR DEM studies covering a large number of these regions.

Plasma evolution mechanism and distribution characteristics of supersonic vehicles

During the flight of hypersonic vehicle, air will be decomposed and ionized due to the “friction” under ultra-high speed, thus forming a plasma layer. Because the plasma has the ability to absorb and reflect electromagnetic waves, the “black barrier” phenomenon is formed. In addition, when the hypersonic vehicle passes through the atmosphere, the surface temperature rises sharply due to aerodynamic heating, and the surface material undergoes a series of complex changes to form ablation. In this paper, the finite volume method and the laminar finite rate model are used to study the flow field velocity, pressure distribution, flow field temperature, and spatial distribution of each component of the aircraft at different Mach numbers, angles of attack, and heights. In the flow field of supersonic aircraft, N and O are mainly concentrated in the tail of the aircraft, NO is mainly concentrated in the head of the aircraft, and N2 and O2 are full of the whole space. Because of the accumulation of NO+ and O2+ in the tail of the aircraft, the charge accumulation is formed, which will further interfere with the electromagnetic wave signal. The mass fraction of N and O increases with the increase in Mach numbers, while the mass fraction of O2 decreases with the increase in Mach numbers. Different angles of attack will affect the asymmetry of the shock wave of the aircraft. In this paper, the evolution mechanism and distribution characteristics of aircraft plasma are revealed, which lay a theoretical foundation for solving the problem of black barrier and ablation.

Influence of electrolytic plasma spatial distribution on nanoporous structure etching on 4H-SiC surface

Single-crystal SiC nanoporous structure has important applications in the field of micro electromechanical systems, chemical sensors and biomedical devices. However, SiC exhibits a strong chemical inertness due to the short interatomic distance and high binding energy, making it significantly challenging to fabricate nanoporous structure. Electrolytic plasma-assisted chemical etching (EPACE) based on electrochemical anodic oxidation and high-activity electrolytic plasma etching is an ideal method for SiC nanoporous structure etching. In which, the spatial distribution of electrolytic plasma has an important impact on EPACE performance, such as etching efficiency and stability. In order to analyze the impact mechanism, this paper studies EPACE in tool electrode mounting posture of vertical and horizontal types by visual observation, real-time recording of voltage-current waveforms during processing, and the morphology analysis of SiC nanoporous structure after etching. It can be found that in the vertical etching type, EPACE can proceed stably because the workpiece immersion depth is greater than the bubble accumulation thickness. However, in the horizontal etching type, bubbles accumulate seriously between the workpiece and the liquid surface, which may cause bubble cavitation and abnormal discharge, leading to damage to the etching surface. The etching current in the vertical etching type is about 1.3 times that of the horizontal etching type, indicating that the bubble mass transfer in the vertical etching type is faster and the etching impedance is smaller, which is beneficial to improve the etching efficiency and obtain a uniform nanoporous structure. Finally, a SiC nanoporous layer with a thickness of 10.6 μm was prepared at etching time t = 50 min in vertical etching type, and the etching efficiency was 212 nm/min. In addition, the prepared nanoporous structure (nanofiber) was connected to the SiC substrate, indicating that it has a good bonding strength.

Nonideal effects on ionization potential depression and ionization balance in dense Al and Au plasmas.

For low-density plasmas, the ionization balance can be properly described by the normal Saha equationin the chemical picture. For dense plasmas, however, nonideal effects due to the interactions between the electrons and ions and among the electrons themselves affect the ionization potential depression and the ionization balance. With the increasing of plasma density, the pressure ionization starts to play a more obvious role and competes with the thermal ionization. Based on a local-density temperature-dependent ion-sphere model, we develop a unified and self-consistent theoretical formalism to simultaneously investigate the ionization potential depression, the ionization balance, and the charge states distributions of the dense plasmas. In this work, we choose Al and Au plasmas as examples as Al is a prototype light element and Au is an important heavy element in many research fields such as in the inertial confinement fusion. The nonideal effect of the free electrons in the plasmas is considered by the single-electron effective potential contributed by both the bound electrons of different charge states and the free electrons in the plasmas. For the Al plasmas, we can reconcile the results of two experiments on measuring the ionization potential depression, in which one experiment can be better explained by the Stewart-Pyatt model while the other fits better with the Ecker-Kröll model. For dense Au plasmas, the results show that the double peak structure of the charge state distribution appears to be a common phenomenon. In particular, the calculated ionization balance shows that the two- and three-peak structures can appear simultaneously for denser Au plasmas above ∼30g/cm^{3}.

Evaluation of Lipid Emulsion-Mediated Sequestration and Redistribution of the Highly Lipophilic Carbamazepine in the Plasma of Rats

Aim: The idea that intravenous lipid emulsion (ILE) may serve as a "reservoir" for lipophilic drugs has emerged in research as an intravascular "lipid sink" effect. Carbamazepine (CBZ) is a widely used anticonvulsant. This compound has a neutral and highly lipophilic structure and can easily cross body membranes. In this study, our hypothesis focused on the potential efficacy of ILE in modulating blood carbamazepine concentrations. Material and Methods: 22 adult Sprague-Dawley rats were divided into four groups. All groups received CBZ at a dose of 20 mg/kg orogastrically. The first group was the control group. In the second group (activated charcoal group), activated charcoal (AC) was administered orogastrically at a dose of 1 g/kg five minutes after orogastric administration of carbamazepine. The third group (lipid group) received ILE at a dose of 3 ml/kg/min at the fifth minute. The fourth group was the saline group, in which 16 ml/kg of 0.9% NaCl was infused at the fifth minute. Blood samples of 0.5 ml were collected at 0, 4, 8, and 24 hours. Plasma was separated by centrifugation (4000 rpm, 10 minutes) and stored at -80oC for determination of CBZ concentrations. An Agilent 6410B HP-1200 LC series (USA) liquid chromatography system was used for analysis. Quantitative analysis was performed in the multiple reaction mode with electrospray positive ionization (ES+). Results: At the 8th hour of orogastric CBZ administration, CBZ concentration was significantly lower in the activated charcoal group than in the lipid and saline groups (p: 0.021; p: 0.023; p<0.05, respectively). There was no significant difference in CBZ concentrations between the other groups at 8 hours (p>0.05). In the lipid group, the increase in CBZ plasma concentrations was statistically significant at 4 and 8 hours compared to 0 hours (p: 0.005; p: 0.005, respectively). Conclusion: In the lipid group, plasma CBZ concentrations increased at 4 and 8 hours in plasma samples from which lipids were separated by differential centrifugation. In the lipid group, no effects favoring drug-lipid sequestration on the plasma distribution of CBZ were observed.

Abstract 4592: Preclinical characterization of ATG-042-198, a novel MTAP null-selective PRMT5 inhibitor

Abstract Background: PRMT5 inhibitors are considered as a promising approach for cancer therapy due to their crucial role in the initiation and progression of many types of malignancies. Nevertheless, the crucial involvement of PRMT5 in controlling hematopoiesis, even in normal cells, resulted in significant on-target-off-tumor hematological toxicity when using first-generation, non-selective PRMT5 inhibitors in clinical settings, which hampered the clinical development of these drugs. The MTAP gene is deleted in around 10-15% of all human malignancies. As a result, the loss of MTAP leads to the buildup of MTA, which can bind to PRMT5 and partially inhibit PRMT5 activity. Inhibitors targeting the PRMT5-MTA complex become a promising strategy for treating MTAPnull cancer in a synthetically lethal manner. Herein, we report the preclinical feature of ATG-042-198, a novel MTAPnull-selective PRMT5 inhibitor. Methods: The in vitro activity and MTAP selectivity of ATG-042-198 on cell proliferation and cellular symmetric dimethylarginine (SDMA) expression were profiled using HCT116 MTAP wild type (wt) cells and HCT116 MTAP knock out (ko) cells, as well as in five MTAPnull cell lines. The in vivo efficacy was tested in cell derived xenograft (CDX) mouse models with HCT116 MTAP wt cells, HCT116 MTAP ko cells and LU99 cells (MTAPnull). The in vitro and in vivo pharmacokinetic properties were assessed with corresponding assay methods. Results: ATG-042-198 demonstrated potent and selectively inhibitory effect on HCT116 MTAP ko cells’ proliferation (IC50=44nM) and SDMA expression (IC50=0.146nM), but very weak effect on HCT116 MTAP wt cells’ proliferation (IC50=4550nM) and SDMA expression (IC50>500nM). Consistently, ATG-042-198 showed excellent anti-proliferation activities on multiple endogenous MTAPnull cell lines (A549, IC50=2nM; LU99, IC50=6nM; U87MG, IC50=11nM; NALM-6, IC50=37nM; MIA PaCa-2, IC50=43nM). ATG-042-198 demonstrated high permeability (Caco2 assay, ER=2), good metabolic stability (Human liver microsomes assay, T1/2>145min), and low risk of drug interaction (CYP inhibition assay, 3A4/2C19/2D6, all IC50>10μM). In vivo PK study showed that ATG-042-198 was well absorbed, with a dose-dependent increase in plasma distribution and high oral bioavailability (F=108%). Plasma free drug concentrations were continuously higher than the IC50 of cell proliferation inhibition within 24 hours after 30mpk administration. In three CDX models (HCT116 MTAP wt, HCT116 MTAP ko and LU99), ATG-042-198 at a dose of 30 mg/kg QD potently and selectively inhibited tumor growth (TGI=-1%, 89% and 106%) without inducing body weight loss. Conclusions: In summary, ATG-042-198 is an oral MTAP null-selective PRMT5 inhibitor with potent efficacy against MTAPnull tumor. It also demonstrated good tolerability and preclinical PK profiles. Citation Format: Ya Kong, Ming Zhang, Lulu Jiang, Ruiting Xu, Bin Jiang, Guoqiang Dai, Yulong He, Huiling Liu, Jay Mei, Bing Hou, Bo Shan. Preclinical characterization of ATG-042-198, a novel MTAP null-selective PRMT5 inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4592.

Observational signatures of Rotating compact objects in Plasma space–time

We have investigated the characteristics of shadows cast by the Kerr black hole in the presence of plasma and compared them to those of a rotating wormhole in a uniform plasma space–time for an observer at infinity. Interestingly, for the same uniform plasma density, the apparent shadow size of the rotating wormhole is always greater than that of the Kerr black hole. To further distinguish the two compact objects we studied the deflection angle and did a comparative study in the presence of the uniform and non-uniform plasma profiles. The goal of this whole exercise is to deepen our understanding of the observational phenomena of these astrophysical objects. The analysis reveals the importance of specific plasma distribution profiles, the impact of plasma on the shadow diameter, and the behavior of deflection angles in different plasma scenarios. We have calculated constraints on the plasma parameters by considering observational data and employing analytical formulations. Our work therefore provides valuable insights into the behavior of light rays near compact objects in plasma space–time.

3D neutronic analysis on compact fusion reactors: PHITS-OpenMC cross-comparison

The development of high temperature superconducting tape technology enabled the design of compact fusion reactors, allowing faster development in the field. The reduced size makes even more important the evaluation of neutron flux on all components and at every region, including at the magnet position, to assess the lifetime of the materials and their performances during operations. Compactness, however, introduces new technological challenges, considering the reduced space available for shielding materials and the consequently harsher radiation environment for both structural and functional materials. Many different particle transport codes have been developed for nuclear engineering and fundamental physics purposes, each one relying on different algorithms and nuclear models, with different features and capabilities. In the present work the transport codes PHITS and OpenMC are compared, testing the impact on integral results such as the tritium breeding ratio and on spatially resolved neutron spectra of different nuclear libraries, nuclear models and codes, on a CAD imported 3D geometry of an ARC like fusion machine. The impact of different neutron source shapes is also investigated, from a simple ring-like source to a realistic toroidal plasma distribution, as well as the possibility of performing calculations on a 10°reduced domain, instead of on a full 360°geometry. The uncertainty introduced by each model and geometry choice is analyzed and the computational time required is briefly discussed.

Abstract B013: In vitro stability and in vivo pharmacokinetic behavior of panobinostat in mouse models for the treatment of CNS tumors

Abstract Aberrant alterations of histone deacetylases (HDACs), an epigenetic regulator, are common in central nervous system (CNS) tumors and HDAC inhibitors have been found to have therapeutic potential for the treatment of CNS tumors. Panobinostat is a pan-HDAC inhibitor that has shown potency against multiple CNS tumors. Panobinostat has a hydroxamic acid side chain, a structural element reported to be susceptible to esterase activity in multiple compounds. Therefore, in vitro stability of panobinostat may allow the prediction of in vivo pharmacokinetic behavior. The objective of this study is to discover the mechanisms influencing the in vitro stability of panobinostat in multiple matrices and evaluate the in vivo pharmacokinetics in mouse models. In vitro stability studies in mouse plasma at different temperatures showed that panobinostat was unstable in mouse plasma and the decomposition rate was temperature-dependent. Meanwhile, panobinostat was stable in phosphate-buffered saline (PBS, pH7.4) tested at the same incubation conditions. Therefore, we propose that enzymatic activity is a contributor of the in vitro instability of panobinostat. Panobinonstat stability was also measured in plasma from different species. Data show that panobinostat was stable in human, monkey and dog plasma while unstable in mouse and rat plasma. The species difference observed was in line with the carboxylesterase 1c (Ces1c) expression among these species, where rodent plasma has abundant Ces1c expression while the other species have no Ces1c in plasma. With this in mind, we evaluated the impact of Ces1c removal from the matrices. We found that panobinostat was stable in plasma collected from Ces1c knockout mice (B6.Cg-Ces1ctm1.1Loc/J), indicating that Ces1c is contributing to the in vitro instability of panobinostat in plasma. To evaluate the influence of Ces1c on its pharmacokinetic behaviors, we studied the plasma and CNS distribution of panobinostat in wild-type C57BL6/J mice and Ces1c knockout mice following an intravenous bolus dose of 10 mg/kg via tail vein. Despite improved in vitro stability of panobinostat in plasma from Ces1c knockout mice compared with that in plasma from wild-type C57BL6/J, in vivo plasma concentration-time profiles were superimposable between these two genotypes. In addition, the CNS delivery of panobinostat was not influenced by the lack of Ces1c. Studies are ongoing to find potential in vivo mechanisms that are protecting the compound from robust in vitro degradation in the plasma. Citation Format: Wenqiu Zhang, Ju-Hee Oh, Wenjuan Zhang, Rachael W. Sirianni, William F. Elmquist. In vitro stability and in vivo pharmacokinetic behavior of panobinostat in mouse models for the treatment of CNS tumors [abstract]. In: Proceedings of the AACR Special Conference on Brain Cancer; 2023 Oct 19-22; Minneapolis, Minnesota. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_1):Abstract nr B013.

Temperature Distribution Within an Ignition Kernel Initiated by a Laser-Induced Plasma

The sizes of, and temperature distributions within, ignition kernels initiated by a Q-switched neodymium-doped yttrium aluminum garnet laser-induced plasma in an unconfined lean premixed hydrogen-air upward jet flow are investigated. The experiments involved a range of jet velocities and a range of deposited laser energies at a fixed height above the exit along the axis of a burner. The growth of, and the temperature distributions within, the ignition kernels, as affected by the size and the energy distribution of the laser-induced plasma, are monitored with an infrared camera. The initial ignition kernels’ areas are larger with higher laser pulse energies and remain unchanged up to 20 μs and then increase by factors of up to 3 at 100 μs. The change in the kernel area caused by the jet velocities is less than 1.5%. An increase of the bulk velocity by 190% decreases the ignition kernel temperature by 6%. This reduction in the ignition kernel temperatures is because of an increase in energy losses by a factor of 2 and decreases in heat releases by 2% at 10 μs and by 11% at 100 μs. The present contributions are: measurements of and insights into temperature distributions and kernel development rates during the laser-induced plasma ignition process at different deposited energies and flow velocities.

The Impact of Non‐Equilibrium Plasma Distributions on Solar Wind Measurements by Vigil's Plasma Analyser

AbstractIn order to protect society from space weather impacts, we must monitor space weather and obtain early warnings for extreme events if possible. For this purpose, the European Space Agency is currently preparing to launch the Vigil mission toward the end of this decade as a space‐weather monitor at the fifth Lagrange point of the Sun–Earth system. Vigil will carry, amongst other instruments, the Plasma Analyser (PLA) to provide quasi‐continuous measurements of solar wind ions. We model the performance of the PLA instrument, considering typical solar wind plasma conditions, to compare the expected observations of PLA with the assumed input conditions of the solar wind. We evaluate the instrument performance under realistic, non‐equilibrium plasma conditions, accounting for temperature anisotropies, proton beams, and the contributions from α‐particles. We examine the accuracy of the instrument's performance over a range of input solar wind moments. We identify sources of potential errors due to non‐equilibrium plasma conditions and link these to instrument characteristics such as its angular and energy resolution and its field of view. We demonstrate the limitations of the instrument and potential improvements such as applying ground‐based fitting techniques to obtain more accurate measurements of the solar wind even under non‐equilibrium plasma conditions. The use of ground processing of plasma moments instead of on‐board processing is crucial for the extraction of reliable measurements.