Range Of Values Research Articles

Reference Values for Water-Specific T1 of the Liver at 3 T: T2*-Compensation and the Confounding Effects of Fat.

T1 mapping of the liver is confounded by the presence of fat. Multiparametric T1 mapping combines fat-water separation with T1-weighting to enable imaging of water-specific T1 (T1Water ), proton density fat fraction (PDFF), and T2* values. However, normative T1Water values in the liver and its dependence on age/sex is unknown. Determine normative values for T1Water in the liver with comparison to MOLLI and evaluate a T2*-compensation approach to reduce T1 variability. Prospective observational; phantoms. One hundred twenty-four controls (56 male, 18-75 years), 50 patients at-risk for liver disease (18 male, 30-76 years). 2.89 T; Saturation-recovery chemical-shift encoded T1 Mapping (SR-CSE); MOLLI. SR-CSE provided T1Water measurements, PDFF and T2* values in the liver across three slices in 6 seconds. These were compared with MOLLI T1 values. A new T2*-compensation approach to reduce T1 variability was evaluated test/re-test reproducibility. Linear regression, ANCOVA, t-test, Bland and Altman, intraclass correlation coefficient (ICC). P < 0.05 was considered statistically significant. Liver T1 values were significantly higher in healthy females (F) than males (M) for both SR-CSE (F-973 ± 78 msec, M-930 ± 72 msec) and MOLLI (F-802 ± 55 msec, M-759 ± 69 msec). T1 values were negatively correlated with age, with similar sex- and age-dependencies observed in T2*. The T2*-compensation model reduced the variability of T1 values by half and removed sex- and age-differences (SR-CSE: F-946 ± 36 msec, M-941 ± 43 msec; MOLLI: F-775 ± 35 msec, M-770 ± 35 msec). At-risk participants had elevated PDFF and T1 values, which became more distinct from the healthy cohort after T2*-compensation. MOLLI systematically underestimated liver T1 values by ~170 msec with an additional positive T1-bias from fat content (~11 msec/1% in PDFF). Reproducibility ICC values were ≥0.96 for all parameters. Liver T1Water values were lower in males and decreased with age, as observed for SR-CSE and MOLLI acquisitions. MOLLI underestimated liver T1 with an additional large positive fat-modulated T1 bias. T2*-compensation removed sex- and age-dependence in liver T1, reduced the range of healthy values and increased T1 group differences between healthy and at-risk groups. 2 TECHNICAL EFFICACY: Stage 1.

In vivo assessment of the ocular biomechanical properties in patients with idiopathic normal pressure hydrocephalus

PurposeIdiopathic normal pressure hydrocephalus (iNPH) is associated with an increased prevalence of open-angle glaucoma, attributed to variations of the pressure gradient between intraocular and intracranial compartments at the level of the lamina cribrosa (LC). As ocular biomechanics influence the behavior of the LC, and a lower corneal hysteresis (CH) has been associated to a higher risk of glaucomatous optic nerve damage, in this study we compared ocular biomechanics of iNPH patients with healthy subjects.Methods Twenty-four eyes of 24 non-shunted iNPH patients were prospectively recruited. Ocular biomechanical properties were investigated using the ocular response analyzer (Reichert Instruments) for the calculation of the CH, corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg), and corneal-compensated intraocular pressure (IOPcc). Results were compared with those of 25 eyes of 25 healthy subjects.Results In iNPH eyes, the median CH value and interquartile range (IQR) were 9.7 mmHg (7.8–10) and 10.6 mmHg (9.3–11.3) in healthy controls (p = 0.015). No significant differences were found in IOPcc [18.1 mmHg (14.72–19.92) vs. 16.4 mmHg (13.05–19.6)], IOPg [15.4 mmHg (12.82–19.7) vs. 15.3 mmHg (12.55–17.35)], and CRF [9.65 mmHg (8.07–11.65) vs. 10.3 mmHg (9.3–11.5)] between iNPH patients and controls.Conclusions In iNPH patients, the CH was significantly lower compared to healthy subjects. This result suggests that ocular biomechanical properties may potentially contribute to the risk of development of glaucomatous optic nerve damage in iNPH patients.

Architecture Design of Internet of things Virtual Laboratory

The development of the internet today has been very developed including for the world of education, one of the technologies is the application of the Internet of Things (IoT) which should be accompanied by an increase in student competence in higher education but is currently still constrained by laboratory facilities, The purpose of this study is to produce an IoT virtual laboratory architecture design, which will then be developed into an IoT virtual lab system. The method used in this research is the waterfall method in the design and design aspects, testing is done using an expert validation instrument to determine the validity level of the virtual laboratory design before entering the implementation or system creation stage. The research has produced an IoT virtual laboratory architecture consisting of three main components, namely (1) virtualab information system, (2) virtual lab manager and (3) system integration through SCORM (Sharable Content Object Reference Model) which is used for integration into the LMS (Learning Management System) system, the results of validation from experts on the design of the IoT virtual laboratory architecture show an average score of 3.56, within the value range of 3.26 to 4.00. This indicates a very good level of quality. This indicates a very good level of quality. However, there are still areas that need to be improved, especially in criterion V2 related to the system development flow diagram which gets an average score of 3.33, so the results of this research design can be used for the system development stage.

Mangrove gastropod distribution based on dominant vegetation classes and their relationship with physicochemical characteristics on fringe mangroves of Lembongan Island, Bali, Indonesia

Abstract. Ernawati NM, Dewi APWK, Sugiana IP, Dharmawan IWE, Ma’ruf MS, Galgani GA. 2024. Mangrove gastropod distribution based on dominant vegetation classes and their relationship with physicochemical characteristics on fringe mangroves of Lembongan Island, Bali, Indonesia. Biodiversitas 25: 156-166. Mangrove ecosystems are important in supporting diverse marine life, offering refuge, reproductive grounds, and sustenance to various species. However, mangroves possess distinct zoning patterns determined by dominant species due to environmental variations that significantly impact the biodiversity of biota, particularly gastropods. A study on the Indonesian island of Nusa Lembongan revealed distinct communities of coexisting gastropod species in each mangrove vegetation zone. We discovered 29 distinct species of mangrove gastropods, with the Sonneratia mangrove zone having the most and the Lumnitzera zone having the least. Certain species, including Amphidromus perversus, Cerithium adustum, and Echinolittorina sundaica, were detected in only one of the mangrove zones. In each mangrove zone, the composition of gastropod species changed depending on the substrate type, e.g., soil, mangrove trunks, or mangrove leaves. The Shannon-Wiener diversity index values range from low to high diversity, and the community structure index values in mangrove zones vary. The evenness index varied by region, with Avicennia, Bruguiera, and Sonneratia having the highest index value. The findings indicate that mangrove vegetation zones are essential for maintaining diverse gastropod populations, with distinct composition and abundance patterns influenced by the distance of each mangrove zone from the ocean. This data may influence conservation efforts to preserve mangrove habitats and the diverse array of organisms that depend on them.

Analysis of Octane Retention Prediction Model for Catalytic Cracked Gasoline Based on Ridge Regression Model and Gradient Descent Optimization

On the basis of the given material, in order to increase the RON retention of the catalytic cracking unit, the prediction model of gasoline octane retention and the best operation variable inversion model were established based on the Ridge regression model and Gradient descent method. First, based on the Ridge regression model, the leave-one method is used to obtain the relative importance of the operational variables, and select the most important variables, so as to reduce the characteristic dimension of the model; Then, the RON retention prediction model is trained based on the Ridge regression model; Finally, based on the trained Ridge regression model and its weight parameters, the optimal operating variables were optimized separately using the gradient when the operation variable has a range or no range of value. The experimental results show that when 146 are selected from 361 operating variables, the model loss value stabilizes; when α is 0.6, the test set R2 is 0.9882, test set MSE is 0.0193, and the comprehensive performance is better than the random forest, support vector machine model; When the operation variable has two categories of value range and no value range, 2,000 times, the best inversion value of the operation variable makes the RON retention prediction value of the test sample similar to the expected value, and the MAE drops to 2.89999�10-3 and 7.62939�10-6, respectively. In conclusion, the RON retention prediction model proposed in this study has good results, and the best operating variable can be reversed, based on the given material parameters, making the optimal RON retention quantity.

Pedestrian level of service for sidewalks in Tangier City

The pedestrian level of service (PLOS) is a measure that quantifies walkway comfort levels. PLOS defined into six categories (A, B, C, D, E, and F) each level defines the range of values, for example, a good level (best traffic condition) is defined with the letter A until reaching the worst level, F (high congestion). This article aims to define the PLOS on sidewalks considering walking conditions in Tangier City (Morocco). Sidewalks are analyzed using video recording in the urban center of Tangier City. The collected data are pedestrian flow and effective sidewalk width. Each level contains a range of values that corresponds to the pedestrian flow that defines the level of service. Clustering techniques are used to identify the threshold of each level using a self-organizing map (SOM). The results are different from those obtained with other methods because pedestrian traffic differs from country to country.

Calculating the Hydraulic Characteristics of Bai Hassan Aquifer in Erbil City/Northern Iraq

Iraq lacks surface water resources, so groundwater extraction is prioritized to meet the demands of the industrial, agricultural, and domestic sectors. The chosen location is the Bai Hassan Formation’s major aquifer for the city of Erbil. The hydrogeological system in the study area within the central basin of the Erbil Plain, is considered the largest part of the basin and water reservoir, which is a confined aquifer. The study aims to describe the hydraulic characteristics of the limited characteristics of the aquifer in Erbil, northern Iraq. The wells that were studied are 300 m deep and penetrate the Bai Hassan Formation and Quaternary sediments. The general direction of the flow of Groundwater in the region is generally toward the western regions. Using methods of Jacob straight line and theis recovery methods, the results of the pumping test conducted in 5 wells without observation wells indicated a transmissivity values range between 80.295-299.6 m2 / day and hydraulic conductivity values range between 0.65-3.565 m/day and this reflects the wide horizontal and vertical variation in the layers of the reservoirs. The measured specific capacity for these wells ranges from 40.4 to 79.6 m2/day, and there is an inverse relationship between the specific capacity and well drawdown.

The relevance of biologically effective dose for pain relief and sensory dysfunction after Gamma Knife radiosurgery for trigeminal neuralgia: an 871-patient multicenter study.

Recent studies have suggested that biologically effective dose (BED) is an important correlate of pain relief and sensory dysfunction after Gamma Knife radiosurgery (GKRS) for trigeminal neuralgia (TN). The goal of this study was to determine if BED is superior to prescription dose in predicting outcomes in TN patients undergoing GKRS as a first procedure. This was a retrospective study of 871 patients with type 1 TN from 13 GKRS centers. Patient demographics, pain characteristics, treatment parameters, and outcomes were reviewed. BED was compared with prescription dose and other dosimetric factors for their predictive value. The median age of the patients was 68 years, and 60% were female. Nearly 70% of patients experienced pain in the V2 and/or V3 dermatomes, predominantly on the right side (60%). Most patients had modified BNI Pain Intensity Scale grade IV or V pain (89.2%) and were taking 1 or 2 pain medications (74.1%). The median prescription dose was 80 Gy (range 62.5-95 Gy). The proximal trigeminal nerve was targeted in 77.9% of cases, and the median follow-up was 21 months (range 6-156 months). Initial pain relief (modified BNI Pain Intensity Scale grades I-IIIa) was noted in 81.8% of evaluable patients at a median of 30 days. Of 709 patients who achieved initial pain relief, 42.3% experienced at least one pain recurrence after GKRS at a median of 44 months, with 49.0% of these patients undergoing a second procedure. New-onset facial numbness occurred in 25.3% of patients after a median of 8 months. Age ≥ 63 years was associated with a higher probability of both initial pain relief and maintaining pain relief. A distal target location was associated with a higher probability of initial and long-term pain relief, but also a higher incidence of sensory dysfunction. BED ≥ 2100 Gy2.47 was predictive of pain relief at 30 days and 1 year for the distal target, whereas physical dose ≥ 85 Gy was significant for the proximal target, but the restricted range of BED values in this subgroup could be a confounding factor. A maximum brainstem point dose ≥ 29.5 Gy was associated with a higher probability of bothersome facial numbness. BED and physical dose were both predictive of pain relief and could be used as treatment planning goals for distal and proximal targets, respectively, while considering maximum brainstem point dose < 29.5 Gy as a potential constraint for bothersome numbness.

Hybrid algorithm for initial phase calibration of optical phased array.

The synthesis of laser coherence and the accuracy of beam scanning, which are based on an optical phased array (OPA), are severely constrained by phase noise. This limitation hampers their applications in various fields. Currently, the most widely utilized calibration method is adaptive optics, which can effectively mitigate phase noise and enhance the quality of the output beam. However, because of the multiple array elements of the OPA and the large optimization range for each element, the adaptive optimization method experiences slow convergence and a high risk of falling into local optima. We propose a narrowing search range algorithm that can quickly reduce phase noise by narrowing the search range of the optimal value. After initial optimization, the SPGD algorithm was used. This study was verified through simulations and experiments utilizing the OPA of various array elements. These findings indicate that the hybrid algorithm expedites the calibration process, requires simple experimental equipment, and can be broadly utilized.

Spherical Langmuir probes in magnetized plasma. A model based on particle-in-cell simulations

We present a new model for current collected by a spherical Langmuir probe in magnetized plasmas. Data are obtained using state-of-the-art fully 3D kinetic particle-in-cell simulations. We perform a dimensional analysis and use it to determine the appropriate model function. The model is then empirically derived based on the simulation data for a range of probe potentials and magnetic field values with respect to the Debye length. The final model function is applicable to most space plasmas and can easily be generalized.

Upscaling of Reactive Mass Transport through Porous Electrodes in Aqueous Flow Batteries

Porous electrodes (PEs) are an important component of modern energy storage devices, such as lithium-ion batteries, flow batteries or fuel cells. Their complicated multiphase structure presents a considerable challenge to modeling and simulation. In this paper, we apply the volume-averaging method (VAM) as an efficient approach for the evaluation of effective macroscopic transport parameters in PEs. We consider the transport of electro-active species coupled to heterogeneous Butler-Volmer type reactions at the electrode surface. We identify the characteristic scales and dimensionless groups for the application to aqueous flow batteries. We validate the VAM-based model with direct numerical simulation results and literature data showing excellent agreement. Subsequently, we characterize several simplified periodic PE structures in 2D and 3D in terms of hydraulic permeability, effective dispersion and the effective kinetic number. We apply the up-scaled transport parameters to a simple macroscopic porous electrode to compare the overall efficiency of different pore-scale structures and material porosity values over a wide range of energy dissipation values. This study also reveals that the Bruggeman correction, commonly used in macroscopic porous electrode models, becomes inaccurate for realistic kinetic numbers in flow battery applications and should be used with care.

Fate of an Earth‐Like Water Inventory on Mars

AbstractWe have determined the global inventory of surface and near‐surface water on Mars by tracking the amounts of water lost to each of the significant sinks for water. The sinks include loss to space, formation of hydrated minerals, possible remnants of an ancient ocean, water present within the crust, and the present‐day polar caps and near‐surface ice deposits; we utilize both previous analyses and new analyses of the amount of water in the sinks. Summed up, they total 380–970 m H2O (as a global equivalent layer), and possibly up to 685–1,970 m if possible crustal liquid water or ice is included. For comparison, the Earth's surface and near‐surface inventory, scaled to Mars, would be 1,400 m. This value for an Earth‐like Mars falls within the range of possible values for Mars, suggesting that Mars had a similar surface inventory of surface and near‐surface water. This abundance of water on early Mars is able to produce the observed water‐related geological features and suggests the presence of an early habitable environment capable of supporting life.

Subsurface Thermophysical Properties of Europa’s Leading and Trailing Hemispheres as Revealed by ALMA

We present best-fit values of porosity—and the corresponding effective thermal inertiae—determined from three different depths in Europa’s near-subsurface (∼1–20 cm). The porosity of the upper ∼20 cm of Europa’s subsurface varies between 75% and 50% (Γeff ≈ 50–140 J m−2 K−1 s−1/2) on the leading hemisphere and 50%–40% (Γeff ≈ 140–180 J m−2 K−1 s−1/2) on the trailing hemisphere. Residual maps produced by comparison with these models reveal thermally anomalous features that cannot be reproduced by globally homogeneous porosity models. These regions are compared to Europa’s surface terrain and known compositional variations. We find that some instances of warm thermal anomalies are co-located with known geographical or compositional features on both the leading and trailing hemisphere; cool temperature anomalies are well correlated with surfaces previously observed to contain pure, crystalline water ice and the expansive rays of Pwyll crater. Anomalous regions correspond to locations with subsurface properties different from those of our best-fit models, such as potentially elevated thermal inertia, decreased emissivity, or more porous regolith. We also find that ALMA observations at ∼3 mm sound below the thermal skin depth of Europa (∼10–15 cm) for a range of porosity values, and thus do not exhibit features indicative of diurnal variability or residuals similar to other frequency bands. Future observations of Europa at higher angular resolution may reveal additional locations of variable subsurface thermophysical properties, while those at other wavelengths will inform our understanding of the regolith compaction length and the effects of external processes on the shallow subsurface.

Monitoring of pH level for maximizing oil palm ffb yields

Depending on the location of estates and types of soils, monitoring of pH changes is an integral part of soil-water management for realizing sustainable Fresh Fruit Bunches (FFB) yields. In Sumber Tani Agung Resources Tbk, fluctuations in pH levels in field blocks as well as nearby drains were monitored since 2019. The usage of portable units of pH meters made it possible for planters to record and monitor the on-site changes in pH. Monitoring of pH was done on two types of soils namely peat (three estates in North Sumatra) and acid sulfate soils (two estates in South Sumatra). Piezometer was established in each block in all five estates and pH reading was taken biweekly, including at nearby watergates for comparison. Lower pH values ranging from 3.5 to 3.7 were observed at piezometers and water gates on blocks established on acid sulfate soils as compared to pH values recorded in peat areas where slightly higher pH values were registered (4.3 to 5.6). The presence of pyrite contributed to a lower range of pH values on acid sulfate soils. Keeping water level at 40-70 cm on peat and at 45-60 cm for acid sulfate soils would have an impact on the improvement of soil physical chemistry and biology properties, besides creating aerobic conditions for roots of the cultivated oil palms. Organic fertilizer such as bunch ash was applied in the 2020-2021 period which also resulted in an increment in pH values. Generally, there were improvements in oil palm growth as well as palm yield performance in areas with higher pH values (>4.50).

Exploring the application of dual‐energy CT to discriminate sediment facies in a varved sequence

AbstractDual‐energy X‐ray computed tomography consists of imaging objects using two incident X‐ray beams of different energy to distinguish the different compounds within a sample based on their density (electron density, ρe) and elemental composition (effective atomic number, Zeff). The stoichiometric calibration for dual‐energy X‐ray computed tomography was already successfully implemented to identify single and homogeneous minerals easily and non‐destructively. It is here applied for the first time to a more complex and heterogeneous sample, a varved sediment core with three distinct facies. The output of dual‐energy X‐ray computed tomography was compared against elemental geochemistry obtained at the same resolution using a micro‐XRF core scanner. The three individual facies can be successfully differentiated using dual‐energy X‐ray computed tomography because their range of ρe and Zeff values allow their discrimination. Correlations with elemental geochemistry are also discussed but are less conclusive, probably because of variations in grain size and porosity, and because these high resolution analyses were not performed at the exact same location. The paper not only eventually discusses the limitations when using dual‐energy X‐ray computed tomography on sediments but also demonstrates its potential to quantitatively study sediment cores in a non‐destructive way.

Dimensional quantization in InSb and GaAs in three-zone model

Various cases of size quantization in narrow-gap crystals of cubic or tetrahedral symmetry in the three-band Kane approximation are analyzed. Expressions for the energy spectrum depending on the two-dimensional wave vector are obtained for two different cases, differing in the range of current carrier energy values. The size-quantized energy spectrum of electrons in the conduction band and holes in the subband of light holes in InSb and GaAs semiconductors is analyzed in the three-band Kane model.

Parendozoicomonas callyspongiae sp. nov. Isolated from a Marine Sponge, Callyspongia elongate, and Reclassification of Sansalvadorimonas verongulae as Parendozoicomonas verongulae comb. nov.

A strictly aerobic Gram-negative bacterium, designated 2012CJ34-2T, was isolated from marine sponge to Chuja-do in Jeju-island, Republic of Korea and taxonomically characterized. Cells were catalase- and oxidase-positive, and non-motile rods (without flagella). Growth was observed at 15-42°C (optimum, 30°C), pH 6-9 (optimum, pH 7), and in the presence of 0.5-10% (w/v) NaCl (optimum, 2-3%). The major cellular fatty acid and respiratory quinones were identified summed feature 3 (C16:1 ω7c/C16:1 ω6c), and Q-8 and Q-9, respectively. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, an unidentified aminophospholipid, two unidentified phospholipids, and three unidentified lipids. The DNA G+C content was 48.0mol%. Phylogenetic analyses based on 16S rRNA gene and whole genome sequences showed that strain 2012CJ34-2T formed a clade with Parendozoicomonas haliclonae S-B4-1UT and Sansalvadorimonas verongulae LMG 29871T within the family Endozoicomodaceae. Genome relatedness values, including dDDH, ANI and AF, and AAI and POCP, among strain 2012CJ34-2T, P. haliclonae S-B4-1UT, and S. verongulae LMG 29871T were within the range of the bacterial genus cut-off values. Based on the phylogenetic, chemotaxonomic, and genomic analyses, strain 2012CJ34-2T represents a novel bacterial species of the family Endozoicomodaceae, for which the name Parendozoicomonas callyspongiae sp. nov. is proposed. The type strain is 2012CJ34-2T (= KACC 22641T = LMG 32581T). Additionally, we proposed the reclassification of Sansalvadorimonas verongulae of the family Hahellaceae as Parendozoicomonas verongulae of the family Endozoicomonadaceae.

Uranium Redox and Deposition Transitions Embedded in Deep‐Time Geochemical Models and Mineral Chemistry Networks

AbstractUranium (U) is an important global energy resource and a redox sensitive trace element that reflects changing environmental conditions and geochemical cycling. The redox evolution of U mineral chemistry can be interrogated to understand the formation and distribution of U deposits and the redox processes involved in U geochemistry throughout Earth history. In this study, geochemical modeling using thermodynamic data, and mineral chemistry network analysis are used to investigate U geochemistry and deposition through time. The number of U6+ mineral localities surpasses the number of U4+ mineral localities in the Paleoproterozoic. Moreover, the number of sedimentary U6+ mineral localities increases earlier in the Phanerozoic than the number of U4+ sedimentary mineral localities, likely due to the necessity of sufficient sedimentary organic matter to reduce U6+–U4+. Indeed, modeling calculations indicate that increased oxidative weathering due to surface oxygenation limited U4+ uraninite (UO2) formation from weathered granite and basalt. Louvain network community detection shows that U6+ forms minerals with many more shared elements and redox states than U4+. The range of weighted Mineral Element Electronegativity Coefficient of Variation (wMEECV) values of U6+ minerals increases through time, particularly during the Phanerozoic. Conversely, the range of wMEECV values of U4+ minerals is consistent through time due to the relative abundance of uraninite, coffinite, and brannerite. The late oxidation and formation of U6+ minerals compared to S6+ minerals illustrates the importance of the development of land plants, organic matter deposition, and redox‐controlled U deposition from ground water in continental sediments during this time‐period.

Effects of pH and salt concentration on freeze-thaw fractionation of soymilk protein.

The two major storage proteins of soymilk are the globulins 7S and 11S. Freeze-thaw fractionation is a simple method for separating these proteins in raw soymilk. In this study, we assessed the freeze-thaw fractionation ability of raw soymilk under various pH (4.3-11.6) conditions and added salt (sodium chloride) concentrations (0.00-0.67 mol L-1). We successfully achieved fractionation within a pH range of 5.8-6.7 and when the salt concentration was 0.22 mol L-1 or lower. Analysis of particle size distribution and microscopic examination of soymilk revealed no direct correlation between particle size and freeze-thaw fractionation ability. Interestingly, it was confirmed that the ranges of zeta potential values associated with successful freeze-thaw fractionation in raw soymilk remained consistent across different pH and salt concentration conditions. These ranges were between -23 and -28 mV at pH levels ranging from 5.8 to 6.7 and between -18 and -29 mV at added salt concentrations ranging from 0 to 0.22 mol L-1. The pH and salt concentration in raw soymilk markedly influence the freeze-thaw fractionation process. We confirmed that the range of zeta potential values where fractionation was possible remained consistent under various pH and salt concentration conditions. These findings suggest that the zeta potential value might serve as an indicator for evaluating the freeze-thaw fractionation ability of raw soymilk. © 2024 Society of Chemical Industry.

Nonadiabatic effects in the electron-optical system of a relativistic millimeter-wave gyrotron

Gyrotrons based on relativistic electron flows generated by thermionic magnetron injection guns are promising pulsed sources of millimeter and submillimeter radiation with multi-megawatt output power. Obviously, to increase the output power of such devices, it is necessary to provide a high beam current of more than 100 A. At the selected emission density, this forces the use of an emitter with a sufficiently large area. As is well known, wide emitters produce beams with a large velocity spread, which reduces the efficiency of the electron-wave interaction. Therefore, it is necessary to increase the diameter and, accordingly, increase the distance from the cathode to the gyrotron cavity, which leads to an increase in the magnetization reversal coefficient. Thus, the magnetic field in the region of beam formation becomes weak, and the Larmor radius and the turn pitch of the electron trajectory become large compared to the geometry of the surrounding electrodes, which can cause nonadiabatic effects. In this work, we consider one of these effects, which consists in the emergence of a range of anode voltage values in which the monotonic growth of the pitch factor stops. The results of trajectory analysis using current tube and discrete source methods based on the ANGEL software package are presented, as well as an assessment of the influence of a magnetic lens on the properties of an electron beam based on a simple analytical model.