Vacuum最新文献

{"title":"Preparation of block cathode through sedimentation process for high current pulsed electron beam emission","authors":"Bohang Yang ,&nbsp;Jie Yu ,&nbsp;Chenxiang Jin ,&nbsp;Ling Zhang ,&nbsp;Huihui Wang ,&nbsp;Shengzhi Hao","doi":"10.1016/j.vacuum.2026.115150","DOIUrl":"10.1016/j.vacuum.2026.115150","url":null,"abstract":"<div><div>A novel preparation technique of block cathode used for high current pulsed electron beam (HCPEB) emission was essayed. Through the sedimentation of short carbon fibers (SCF) of length 6 mm and adhesion of phenol formaldehyde resin (PFR) of concentration from 6 to 24 wt%, the discrete SCF could be integrated randomly and constituted a desirable structure. The microstructure of cathode was investigated by using X-ray microscopy (XRM) and scanning electron microscopy (SEM). The results showed that a stacked network of SCF was formed homogenously without the bundling phenomena. The carbonized PFR was found at the intersections of SCF. With the PFR of 24 wt%, the severe agglomeration was noticed with an appearance of spheres. The density of cathode increased with the content of SCF and PFR, as well as its capacity of structure maintenance. Contrarily, the resistance rate and evacuation speed were ruined by the density of block cathode. Considering the working requirements, the optimized parameter was selected as the SCF of 6 g and PFR of 12 wt%. The cathode was tested by the HCPEB emission experiment and exhibited satisfactory performance, including the spot size, energy uniformity, emission stability and long-term durability performance.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115150"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation of plasma in a 915 MHz MPCVD reactor using a simplified 2D structure","authors":"Xue Liu,&nbsp;Cuiting Zhang,&nbsp;Xianyi Lv,&nbsp;Qiliang Wang,&nbsp;Liuan Li,&nbsp;Guangtian Zou","doi":"10.1016/j.vacuum.2026.115159","DOIUrl":"10.1016/j.vacuum.2026.115159","url":null,"abstract":"<div><div>This study numerically investigates a 915 MHz iplas-type MPCVD reactor. Electromagnetic analysis identified the TE₁₀ mode in the annular waveguide and the TM₀₁₂ mode in the resonant cavity, clarifying the slot antenna's magnetic coupling mechanism. Subsequently, multi-dimensional simulations were conducted on the iplas cavity. Firstly, a plasma simulation was carried out based on the phenomenological method, and it was found that there were limitations in characterizing the spatial variations. To more accurately simulate plasma spatial distribution, an innovative approach was adopted, which reasonably simplified the non-axisymmetric three-dimensional (3D) cavity into a two-dimensional (2D) axisymmetric structure, and a self-consistent pure hydrogen plasma simulation was then carried out. The results showed that, at a fixed power, an increase in pressure led to plasma contraction and an increase in electron number density; at a fixed pressure, an increase in power caused plasma expansion, and when exceeding the critical value, the central electron number density decreased. Three sets of process parameters were selected for simulation and experiment validation, verifying the accuracy of the simulation prediction results using this simplified structure. Under the simulated process conditions (30 kW-10.5 kPa), high-quality 6-inch polycrystalline diamond films were successfully deposited.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115159"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Probing the structural, electronic, optical, magnetic and mechanical properties of CaX3H9 (X = Cr, Mn, Fe) hydrides towards next-generation hydrogen storage applications","authors":"Bilal Ahmed ,&nbsp;Muhammad Bilal Tahir ,&nbsp;Arafa A. Yagob ,&nbsp;Mohja Jaouadi ,&nbsp;Solima I. Yagoob","doi":"10.1016/j.vacuum.2026.115161","DOIUrl":"10.1016/j.vacuum.2026.115161","url":null,"abstract":"<div><div>Acquiring hydride materials that are structurally stable, have good hydrogen absorption thermodynamics, and have several useful physical properties is still a major challenge for next-generation hydrogen storage methods. This study presents the inaugural full first-principles analysis of hitherto unexamined cubic CaX₃H₉ (X = Cr, Mn, Fe) hydrides, employing density functional theory inside the CASTEP framework. Structural optimization, negative formation enthalpies (−0.081 to −0.078 eV/atom), phonon dispersion without imaginary modes, and ab initio molecular dynamics simulations up to 800 K all show that they are thermodynamically, dynamically, and thermally stable. Calculations of the electronic structure show that substantial transition-metal 3d–H-1s hybridization causes inherent metallic behavior. This is also related to how hydrogen moves and how it can be reversed. Spin-polarized computations reveal unique magnetic ground states: CaCr₃H₉ and CaFe₃H₉ display ferromagnetism, but CaMn₃H₉ stabilizes in an antiferromagnetic arrangement. The elastic constant analysis shows that all of the compounds are mechanically stable. However, CaMn₃H₉ and CaFe₃H₉ are ductile (B/G &gt; 2.2), whereas CaCr₃H₉ is brittle. Optical spectra show that the material absorbs a lot of light in the visible to UV range, mostly because of interband transitions between transition-metal d-states. This shows that the material has more optoelectronic functions. Most crucially, CaX₃H₉ hydrides store hydrogen well, with gravimetric capacities of 4.35, 4.24, and 4.19 wt% and volumetric capacities of 176.8–183.0 gH₂ L⁻¹ for CaX₃H₉ (X = Cr, Mn, Fe), respectively. They also have moderate desorption temperatures (521–538 K). These findings identify CaX₃H₉ as an innovative and adjustable category of perovskite-like hydrides that integrate structural stability, metallic conductivity, magnetic ordering, and effective hydrogen storage capabilities, presenting a viable foundation for enhanced solid-state hydrogen energy systems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115161"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative effects of peracetic and percitric acid treatments under autoclave and water bath heating on the structural transformation of cellulose sago pith waste","authors":"Maghfirah Jayalaksamana ,&nbsp;Nanang Masruchin ,&nbsp;Makhmudun Ainuri ,&nbsp;Herman Marius Zendrato","doi":"10.1016/j.vacuum.2026.115167","DOIUrl":"10.1016/j.vacuum.2026.115167","url":null,"abstract":"<div><div>Global environmental awareness has driven strategies to convert waste into high-value products in an eco-friendly manner. One approach involves utilizing sago pith waste (SPW), a by-product of sago starch extraction, to produce nanomaterials: microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC). This study evaluates the efficiency of transforming SPW pretreated with alkaline hydrogen peroxide (AHP) using peracetic acid (PAA) and percitric acid (PCA) under autoclave and water bath heating. AHP pretreatment increases fiber accessibility by reacting SPW with a mixture of 5 wt% NaOH and 5 vol% H₂O₂ (1:1 v/v). PAA treatment reacts AHP-pretreated SPW with H₂O₂, CH₃COOH, and H₂O (50:30:20 v/v) at 121 °C and 0.1 MPa in an autoclave or 95 °C in a water bath for 60 min. PCA treatment follows the same temperature sequence using H₂O₂ and citric acid (1:1 v/v). It is found that PCA effectively oxidizes lignin and hydrolyzes cellulose, while the water bath prevents rapid H₂O₂ decomposition, allowing longer reaction time for acid ions with SPW fibers. PCA treatment under water bath heating produces cellulose with white color, high crystallinity (79%), uniform morphology (diameter 25.73 μm, length 86.47 μm), intact functional groups, estimated degree of polymerization (541.2), thermal stability (T_max 361 °C), and oil- (2.32 g/g) and water-holding capacity (4.10 g/g) comparable to commercial MCC. The same treatment yields NCC with average diameter 16.33 nm and length 276.01 nm, stably dispersed in solution. These results demonstrate that water bath heat source can effectively serve as a sustainable source of simultaneous MCC and NCC production from SPW through to support eco-friendly manner compared to autoclave heat source.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115167"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tailoring peritectic solidification and lamellar orientation in TiAl alloys through controlled heating power","authors":"Xiaokang Yang ,&nbsp;Hongze Fang ,&nbsp;Lingyan Zhou ,&nbsp;Xianfei Ding ,&nbsp;Fuxin Wang ,&nbsp;Bobo Li ,&nbsp;Baohui Zhu ,&nbsp;Ruirun Chen","doi":"10.1016/j.vacuum.2026.115128","DOIUrl":"10.1016/j.vacuum.2026.115128","url":null,"abstract":"<div><div>The influence of temperature gradient on the microstructure and high-temperature mechanical behavior of directionally solidified Ti-47Al-6Nb-0.1C-1.6Ta-0.8Hf alloys was systematically investigated. Columnar grain alignment and lamellar orientation improve with increasing power up to 45 kW, beyond which orientation dispersion and equiaxed grains emerge, driven by the stability of the solidification front and competitive β-dendrite growth. High temperature gradients enhance peritectic reaction kinetics, promoting α-variant selection, lamellar convergence, and suppression of residual β, whereas low gradients lead to dispersed lamellar structures. Elemental analysis reveals uniform hydrogen and oxygen distribution with minimal segregation, attributed to high-vacuum melting and rapid peritectic consumption of β. High-temperature tensile testing at 900 °C shows peak strength and ductility at 45 kW, correlated with effective dislocation blockage at B2/γ and γ/α2 interfaces, where high slip-energy barriers and controlled dislocation transmission mitigate local stress concentrations. These findings demonstrate that precise control of heating power and temperature gradient enables the optimization of microstructure, phase transformation, and high-temperature mechanical performance in TiAl alloys.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115128"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the electronic subsystem influence on the rhodium thermodynamic properties","authors":"Mahach N. Magomedov","doi":"10.1016/j.vacuum.2026.115089","DOIUrl":"10.1016/j.vacuum.2026.115089","url":null,"abstract":"<div><div>The properties of rhodium (Rh) have been calculated analytically, both without and taking into account the electronic subsystem (ELS). The ELS effect on the baric (<em>P</em>) and temperature (<em>T</em>) dependences of Rh properties has been studied. It was shown that when ELS is taken into account, both the isotherms of the equation of state and the <em>P-T</em> dependences of the following properties change negligibly: the Debye temperature, the Grüneisen parameter, the elastic modulus (<em>B</em>_<em>T</em>), the specific surface energy (σ), the isochoric derivative of the σ function with respect to temperature and the isothermal derivative of the σ function with respect to pressure. When ELS is taken into account at high temperatures and low pressures, the following properties change noticeably: the thermal expansion coefficient (α_<em>p</em>), isochoric and isobaric (<em>c</em>_<em>p</em>) heat capacity, the product α_<em>p</em>·<em>B</em>_<em>T</em>, and the isobaric derivative of the σ function with respect to temperature. When ELS is taken into account, the agreement of calculated dependencies with experimental data improves. For example, at <em>P</em> = 0 and <em>T</em> = 2000 K, for α_<em>p</em>, consent improves by 11 %, for <em>c</em>_<em>p</em>, consent improves by 23.5 %. With increasing pressure, the ELS contribution to the properties decreases. It was shown that at a certain temperature (<em>T</em>_<em>B</em>), the product α_<em>p</em>·<em>B</em>_<em>T</em> does not change with an isothermal increase in pressure. At <em>T</em> &lt; <em>T</em>_<em>B</em>, the α_<em>p</em>·<em>B</em>_<em>T</em> function decreases, and at <em>T</em> &gt; <em>T</em>_<em>B</em>, the α_<em>p</em>·<em>B</em>_<em>T</em> function increases with isothermal pressure increase. For fcc-Rh was obtained <em>T</em>_<em>B</em> = 188.5 K and it does not depend on the ELS accounting. Calculations of the baric dependence of the melting point, <em>T</em>_<em>m</em>(<em>P</em>), have shown that the ELS influence on the <em>T</em>_<em>m</em>(<em>P</em>) dependence for fcc-Rh is very small even at low pressures.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115089"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating the impact of rapid thermal annealing atmosphere on the properties of sputtered SnO thin films with a tellurium capping layer","authors":"Bojun Zhang ,&nbsp;Kai-Jhih Gan ,&nbsp;Zefu Zhao ,&nbsp;Jialong Xiang ,&nbsp;Zhibo Zeng ,&nbsp;Kuei-Shu Chang-Liao ,&nbsp;Chao-Yi Fang ,&nbsp;Dun-Bao Ruan","doi":"10.1016/j.vacuum.2026.115148","DOIUrl":"10.1016/j.vacuum.2026.115148","url":null,"abstract":"<div><div>Herein, an interface-engineered strategy was developed to enhance the structural and electrical properties of tin monoxide (SnO) thin films by using tellurium (Te) as a surface capping layer and controlling the annealing atmosphere via rapid thermal annealing (RTA). The Te layer effectively stabilized the SnO surface and suppressed Sn valence drift. X-ray photoelectron spectroscopy depth profiling revealed that RTA under the N₂ atmosphere significantly promoted Te⁰ diffusion into SnO. X-ray diffraction confirmed improved crystallinity and grain coarsening in the N₂-annealed sample, attributed to interfacial atomic rearrangement. These findings highlight the synergistic role of Te coating and inert-atmosphere annealing in tuning interfacial defect chemistry and enhancing the physical properties of p-type oxide semiconductors.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115148"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient collision algorithms in DSMC for rarefied gas dynamics: Markovian NTC-pre-scan and Bernoulli-trial schemes","authors":"Ahmad Shoja-sani ,&nbsp;Ehsan Roohi ,&nbsp;Maryam Javani ,&nbsp;Hassan Akhlaghi ,&nbsp;Stefan Stefanov","doi":"10.1016/j.vacuum.2026.115138","DOIUrl":"10.1016/j.vacuum.2026.115138","url":null,"abstract":"<div><div>The collision process is essential to the Direct Simulation Monte Carlo (DSMC) method, as it incorporates the fundamental principles of the Boltzmann and Kac stochastic equations. The primary impetus of this paper is to rectify a long-standing theoretical flaw in the widely used no-time-counter (NTC) collision algorithm. We demonstrate that the standard NTC scheme is fundamentally non-Markovian, relying on a fixed majorant product that introduces a system ‘memory’ and leads to inaccuracies at low particle counts. We propose a new algorithm, NTC-Pre-Scan, which transforms the scheme into a fully Markovian process. When repeated collisions are not crucial, our new NTC scheme, called NTC-Pre-Scan, can operate accurately with a very low number of particles per cell (PPC), with average PPC &lt; 1 (e.g., PPC = 0.01), resulting in several empty cells in simulations. This contrasts with the standard NTC schemes, which typically require a PPC greater than 1. Then, a systematic evaluation of different Bernoulli-Trial (BT)-based collision partner selection schemes, including the simplified Bernoulli trials (SBT), generalized Bernoulli trials (GBT), symmetrized and simplified Bernoulli trials (SSBT), and the newly proposed symmetrized and generalized Bernoulli trials (SGBT), is conducted to treat some benchmark rarefied gas dynamics problems. The results show that the BT-based collision algorithms and NTC-Pre-scan successfully maintain the collision frequency as the number of particles per cell decreases. Simulation of the Bobylev-Krook-Wu (BKW) problem, for which an exact solution of the Boltzmann equation is available, indicates that, like the GBT, the SGBT algorithm yields the same results as theory for the average of the fourth moment of the velocity distribution function (VDF). The simulation on the three-dimensional computational grid for the GBT and SGBT schemes matches the fourth moment of the velocity component of the VDF exactly with the analytical solution. Performance analysis in a micro cavity reveals that the GBT, SSBT, and SGBT decrease the computational cost of simulation. Specifically, the computational cost of the SGBT scheme has been reduced by around 40 % when an appropriate selection number (<em>N</em>_<em>sel</em>) is chosen, and this scheme requires a sample size of 0.62 of the NTC scheme. Finally, we demonstrate that all algorithms successfully capture complex flow phenomena, such as shock waves, in the case of hypersonic flow over a cylinder. Moreover, in the cylinder problem, the SGBT scheme can achieve the same level of accuracy with 28 % less computational cost and an outstanding sample size of 0.319 of the nearest neighbor (NN) scheme, which is the modern invariant of the NTC scheme. These advancements enable accurate simulation of rarefied gases with fewer particles (NTC-Pre-Scan) and lower computational cost (SGBT), which is directly beneficial for the design of complex vacuum systems.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115138"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174073","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microstructure and mechanical properties of Ti150/Ti180 dissimilar brazed joints with titanium-based filler metal","authors":"Xinlei Ding ,&nbsp;Yunjia Huang ,&nbsp;Wei Guo ,&nbsp;Jiapeng Dong ,&nbsp;Da Zhang ,&nbsp;Yeming Guo","doi":"10.1016/j.vacuum.2026.115164","DOIUrl":"10.1016/j.vacuum.2026.115164","url":null,"abstract":"<div><div>The dissimilar titanium alloys Ti150 and Ti180 were brazed using TiZrCuNi filler metal within 890-940 °C for 10 min. Effective joining has been achieved through systematic parameter optimization. Through systematic optimization of the processing parameters, effective bonding was successfully achieved. At relatively low temperatures, excessive formation of brittle intermetallic compounds, namely (Ti,Zr)₂(Cu,Ni), was observed, leading to pronounced hardness mismatch and preferential crack initiation. The diffusion-affected zone was mainly composed of acicular and blocky α/β-Ti phases. Increasing the brazing temperature promotes the fragmentation of coarse intermetallic compounds into finer precipitates, thereby enabling effective regulation of the interfacial microstructure.The maximum shear strength of 432 MPa was achieved at 930 °C, corresponding well with the optimal homogenization of the microstructure. However, when the temperature was further increased to 940 °C, significant grain coarsening occurred in the base material, resulting in a gradual deterioration of the mechanical properties.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115164"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A simplified method for calculating background gas distribution of large-scale neutral beam injector","authors":"Bin Li ,&nbsp;Qianxu Wang ,&nbsp;Jianglong Wei ,&nbsp;Fang Wang ,&nbsp;Lunhuan Xia ,&nbsp;Yue Yun ,&nbsp;Wei Yi ,&nbsp;Yuanlai Xie","doi":"10.1016/j.vacuum.2026.115163","DOIUrl":"10.1016/j.vacuum.2026.115163","url":null,"abstract":"<div><div>Neutral beam injectors (NBIs) are widely employed in fusion devices, where the background gas distribution inside the beamline vessel strongly influences both neutralization efficiency and reionization loss. The mainstream calculation methods are Monte Carlo or angular coefficient methods. However, the large size and intricate internal structure of cryopumps make whole-vessel computations difficult. This paper presents a two-step approach. First, the effective capture coefficient of each cryopump unit is obtained with a detailed Test Particle Monte Carlo (TPMC) model. Second, a reduced geometry of the beamline vessel and components-especially the cryopumps-is used to build the background gas distribution. Line integrals of this distribution evaluate neutralization efficiency and reionization loss. Comparisons between measured and computed pressures in the operational EAST (Experimental Advanced Superconducting Tokamak) NBI and the CRAFT (Comprehensive Research Facility for Fusion Technology) NBI testbed verify the method's generality, and the same procedure is applied to upgrade EAST NBI and BEST (Burning plasma Experimental Superconducting Tokamak) NBI to predict its gas profile and the beam performance.</div></div>","PeriodicalId":23559,"journal":{"name":"Vacuum","volume":"247 ","pages":"Article 115163"},"PeriodicalIF":3.9,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146174107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}