Fusion Of Particles Research Articles

Plasma-induced nanogap narrowing and morphological transformation in gold nanoparticle assemblies.

The plasmonic properties of gold nanoparticle (AuNP) assemblies are critically influenced by the nanogaps between particles. Here, we demonstrate that plasma treatment effectively narrows these nanogaps and ultimately merges the nanoparticles. This process induces a sequential redshift, weakening, broadening, and an eventual blueshift of the plasmon coupling peak in UV-vis spectra, indicating transitions from classical to quantum regimes and finally to contact modes. Surface-enhanced Raman spectroscopy reveals an initial increase in intensity as the nanogaps narrow, followed by a decline as linker molecules are removed. Transmission electron microscopy images further show significant deformation of AuNPs after 5 min of plasma treatment. Based on these combined observations, we propose that the oxidative desorption of thiol linkers causes the collapse of self-assembled monolayers, leading to the gradual narrowing of nanogaps and eventual particle fusion. This plasma-induced transformation also enables the creation of novel AuNP shapes, such as nano-snowmen and particles with protruding morphologies, by merging heterodimers or core-satellite structures. Our findings not only deepen the understanding of plasma effects on nanoparticle assemblies but also expand the utility of plasma treatment for controlling nanogap distances and fabricating exotic nanoparticle shapes.

Precise Control of Two-Dimensional Hexagonal Platelets via Scalable, One-Pot Assembly Pathways Using Block Copolymers with Crystalline Side Chains.

Crystallization-driven self-assembly (CDSA) of block copolymers (BCPs) in selective solvents provides a promising route for direct access to two-dimensional (2D) platelet micelles with excellent uniformity, although significant limitations also exist for this robust approach, such as tedious, multistep procedures, and low yield of assembled materials. Herein, we report a facile strategy for massively preparing 2D, highly symmetric hexagonal platelets with precise control over their dimensions based on BCPs with crystalline side chains. Mechanistic studies unveiled that the formation of hexagonal platelets was subjected to a hierarchical self-assembly process, involving an initial stage of formation of kinetically trapped spheres upon cooling driven by solvophobic interactions, and a second stage of fusion of such spheres to the 2D nuclei to initiate the lateral growth of hexagonal platelets via sequential particle attachments driven by thermodynamically ordered reorganization of the BCP upon aging. Moreover, the size of the developed 2D hexagonal platelets could be finely regulated by altering the copolymer concentration over a broad concentration range, enabling scale-up to a total solids concentration of at least 6% w/w. Our work reveals a new mechanism to create uniform 2D core-shell nanoparticles dictated by crystallization and particle fusion, while it also provides an alternative facile strategy for the design of soft materials with precise control of their dimensions, as well as for the scalability of the derived nanostructures.

A preparation method for mRNA-LNPs with improved properties

The properties of mRNA lipid nanoparticles (mRNA-LNPs), including size, empty particles, morphology, storage stability, and transfection potency, are critically dependent on the preparation methods. Here, a Two-step tangential-flow filtration (TFF) method was successfully employed to improve the properties of mRNA-LNPs during the preparation process. This method involves an additional ethanol removal step prior to the particle fusion process. Notably, this innovative approach has yielded mRNA-LNPs with larger particles, a reduced proportion of empty LNPs, optimized storage stability (at least 6 months at 2–8 °C), improved in vitro transfection efficiency, and minimized distribution in the heart and blood in vivo. In summary, this study represents the implementation of the innovative Two-step TFF method in the preparation of mRNA-LNPs. Our findings indicate substantial enhancements in the properties of our mRNA-LNPs, specifically with regard to the percentage of empty LNPs, stability, transfection efficiency, and in vivo distribution. These improvements have the potential to optimize their industrial applicability and expand their clinical use.

Impact of Tantalum added to Ni-based positive electrode materials for Lithium-ion Batteries

Tantalum-containing, LiNiO2 was synthesized by first coating Ni(OH)2 precursor with nano-Ta2O5 by dry particle fusion. The coated precursor was then heated with LiOH·H2O to form the layered oxide. By analogy with our previous work on tungsten-containing LiNiO2, it is believed the Ta is present in the samples as a LixTayOz secondary phase which coats the grain boundaries of the primary particles within the secondary particles. The structural and electrochemical properties of the synthesized samples were studied by x-ray diffraction (XRD), extended x-ray absorption fine structure (EXAFS), scanning electron microscopy (SEM) and long term charge-discharge cycling tests. Among all the samples created, LiNiO2 containing 0.75 mol% Ta showed the best capacity retention of 94.4 % after 60 cycles between 4.3 and 3.0 V at 30 °C.

Influence of rare earth elements addition in layered double hydroxide catalysts on the yield of growing carbon nanotubes

Efficient preparation of low-cost multi walled carbon nanotubes (MWCNTs) will make them more competitive in the application of lithium ion battery composite additives and conductive paste. For a long time, the catalyst with high activity is the key factor to prepare MWCNT. In this paper, rare earth elements (RE) were introduced into layered double/triple hydroxides (LDH/LTHs) catalyst for the first time to prepare a composite catalyst with high activity, and then MWCNT with high yield was prepared by chemical vapor deposition (CVD). Temperature and the introduction of RE elements will strongly affect the yield of MWCNTs. La, Ce, Dy and Pr can improve the catalytic efficiency of LTHs while Eu, Er and Nd reduce their catalytic efficiency. Specifically, the addition of Dy element can nearly double the productivity of CNTs at 650 °C, reaching to 3093 %. Further analysis shows that the strong magnetic effect of Dy element can surround the iron nanoparticles, effectively inhibiting the fusion of iron particles at high temperatures, and improving the catalytic activity of the catalyst.

Fabrication, characterization, and mechanical properties and wear characteristics of graphite nanoplatelets incorporated nanotwinned Cu composites

The present research is focused on the study of microstructural evolution and mechanical behaviour of graphite nanoplatelet (xGnP, where x = multiple layers of graphene) (a graphene isotope) incorporated Cu composites. The limited excellence of Cu in the mechanical field is enhanced by the incorporation of xGnP nanoreinforcement. A dispersion extent of nanoplatelets over the matrix via ultrasonication is reported. The ex-situ fabrication is carried out through powder metallurgy followed by particle fusion via furnace sintering and spark plasma (SP) sintering. Results of characterization showed the homogeneous distribution of graphite nanoplatelet throughout the Cu matrix at lower graphite nanoplatelet loading concentrations. It is also recognized that both furnace sintered and SP sintered Cu composites showed a remarkable enhancement in mechanical properties and wear behaviour with respect to that of similarly fabricated monolithic pure Cu samples. Cu twins are evident in the optical micrographs. The higher incorporation concentration of the graphite nanoplatelet limits the optimum values thus resulting in the non-uniform distribution of the graphite nanoplatelet, formation of relatively bigger conglomerates, and generation of pores. This in turn limited the mechanical performance at higher graphite nanoplatelet loading concentrations due to uneven hardness, poor densification, formation of cracks, and bigger delamination on the surface during the wear of the samples.

Selective laser sintering additive manufacturing of solid oral dosage form: Effect of laser power and hatch spacing on the physico-technical behaviour of sintered printlets

Selective laser sintering is a laser-based powder bed fusion 3D printing technique in which, the laser parameters plays a vital role in the fusion of polymeric powder particles and the behavior of the final printed object. Hence, the objective of the current study was to investigate the impact of laser power and hatch spacing on the fusion of particles, followed by their physicochemical and mechanical behavior investigations of the final sintered object made with dapsone and poly (1-vinylpyrrolidone-co-vinyl acetate) as a model drug and polymer, respectively. An increase in laser power and a decrease in hatch spacing improved particle fusion, resulting in smoother surface, increased density, and better mechanical properties. Interestingly, there was a loss of drug crystallinity was experienced in respect to varied laser parameters, highlighting the potential of laser-based powder bed fusion technique in developing amorphous solid dispersions. Despite extensive laser parameters, drug entrapment efficiency was found to be greater than 90 % for all sintered batches. No notable differences were observed in the dissolution behavior of all performed samples although it was anticipated to achieve as there was differences witnessed in porosity and disintegration time. Finally, the oral pharmacokinetics study revealed the comparable performance of the sintered dosage form with the tablet prepared with conventional direct compression techniques. Overall, these findings demonstrate that with varying laser parameters, various properties of the final sintered object can be manipulated which further showed the flexibility of this 3D printing technique to fabricate dosage form with a more personalized and customized needs.

Particle fusion of super-resolution data reveals the unit structure of Nup96 in Nuclear Pore Complex

Single molecule localization microscopy offers resolution nearly down to the molecular level with specific molecular labelling, and is thereby a promising tool for structural biology. In practice, however, the actual value to this field is limited primarily by incomplete fluorescent labelling of the structure. This missing information can be completed by merging information from many structurally identical particles in a particle fusion approach similar to cryo-EM single-particle analysis. In this paper, we present a data analysis of particle fusion results of fluorescently labelled Nup96 nucleoporins in the Nuclear Pore Complex to show that Nup96 occurs in a spatial arrangement of two rings of 8 units with two Nup96 copies per unit giving a total of 32 Nup96 copies per pore. We use Artificial Intelligence assisted modeling in Alphafold to extend the existing cryo-EM model of Nup96 to accurately pinpoint the positions of the fluorescent labels and show the accuracy of the match between fluorescent and cryo-EM data to be better than 3 nm in-plane and 5 nm out-of-plane.

Effect of Sintering Temperature on the Thermoelectric Properties of Ag2Se Fabricated by Spark Plasma Sintering with High Compression

Silver selenide (Ag2Se) is a high‐performance thermoelectric (TE) material near room temperature. This research improves its TE figure‐of‐merit (ZT) by varying the sintering temperatures (423–723 K) in the spark plasma sintering (SPS) process with high compression pressure (300 MPa). The SPS compaction of Ag2Se powders synthesized by wet chemical reaction leads to the fast fusion of particles so that the grain boundaries are hardly visible. Furthermore, the fast fusion causes nanopores at the grain surface and some cracks, particularly at higher sintering temperatures. These featured microstructures decrease carrier concentrations and affect the TE properties significantly. The TE measurements show that increasing sintering temperatures results in decreased electrical conductivity and increased magnitude of the Seebeck coefficient due to microstructural defects. Increasing SPS temperatures also suppresses the thermal conductivity from enhancing phonon scattering by defects. The bulk Ag2Se sample sintered at 723 K shows the best TE performance with the maximum ZT of 0.90 with a slight variation from 300 to 400 K. Thus, the high‐temperature SPS with high‐compression pressure is likely to be the key for fabricating bulk Ag2Se with high TE performance.

Performance of low-loss demountable joints between CORC® cable-in-conduit-conductors at magnetic fields up to 8 T developed for fusion magnets

High-temperature superconductors (HTS) are promising candidates for use in the high-field magnets needed in particle accelerators and fusion reactors. HTS conductor on round core (CORC®) cables and wires wound from ReBa2Cu3O7-x (REBCO) coated tapes are being developed for use in high-field magnet applications including fusion magnets operating at currents beyond 80 kA, requiring them to be bundled into cable-in-conduit conductor (CICC) configurations. The use of HTS cables enable demountable superconducting fusion magnets that would allow easier access to the fusion machine for maintenance and parts replacement. Such demountable magnets require practical, low-resistance joints, capable of injecting current uniformly into the many REBCO tapes that make up different cable designs. Optimization steps on CORC® cables have resulted in high-current terminations and joints with a joint resistance measured between a pair of 30-tape CORC® cables of 51 nΩ at 76 K and 1.9 nΩ at 4 K. Demountable joints between CICCs consisting of six CORC® cables arranged in flat and round configurations were also tested and compared to joints between low-temperature superconducting (LTS) CICCs consisting of NbTi Rutherford cables. Samples were paired into two configurations (LTS-to-LTS and HTS-to-HTS) with a demountable joint between them that were each tested in series with currents up to 10 000 A in an applied background magnetic field of up to 8 T. The total loop resistance of the HTS-to-HTS sample, including their terminations and joint, was about 4 nΩ at 4 K in self-field with the resistance of the copper pressed joint being less than 1 nΩ. At 8 T, the total loop resistance increased to 6.9 nΩ with the pressed joint contributing 1.4 nΩ. These initial tests prove the feasibility of producing remountable (dry) joints with low resistance between superconducting magnet windings in future compact fusion machines.

Polymer presence in boundary layer flow and heat transfer of dusty fluid over a stretching surface

PurposeTo explore the fusion of dust particles and of polymers in a viscous liquid is the main purpose of this article. Newtonian fluid as a base fluid is considered and the mutual presence of polymers and dusty bodies is investigated. It discusses the steady laminar flow and heat transportation of a polymeric dusty liquid induced by a uniformly heated, penetrable and stretchable surface inside the boundary layer.Design/methodology/approachThe mathematical system incorporates separate equations of energy and momentum for dusty bodies and for fluid. The classical Oldroyd-B model is chosen for exploring polymer presence. For the fluid phase, this model adds another stress to the conservation law of momentum. Appropriate similarity variables are introduced to transform the system of partial differential equations (PDEs) into a system of nonlinear ordinary differential equations (ODEs). The problem is solved by introducing a numerical iterative procedure which turned out to be fastly converging.FindingsExpeditious changes inside the boundary layer cause polymers to deform. No changes outside the boundary layer are noticed on account of polymer stretching. The dependence of heat transfer rate and skin friction on the parameter of polymer concentration and Weissenberg number is analyzed and displayed graphically against interaction parameters for temperature and velocity, dust particles’ mass concentration, Eckert and Prandtl numbers. Combining effects of polymers and dust particles cause skin friction to decrease and heat transfer rate to increase. Increasing values of interaction parameter for velocity, dust particles’ mass concentration and Eckert number reduces the drag coefficient and local Nusselt number. On the other hand, the Prandtl number and interaction parameter of temperature magnify the heat flux at the wall.Research limitations/implicationsThis article studies the infinite extensibility of polymers. FENE and FENE-P models can be used to investigate the polymer presence in dusty fluids in the future.Originality/valueIn this article, the authors’ aim is to study the combined presence of polymers and dusty bodies. Keeping the existing literature in view, this type of fusion is not studied yet. Polymer inclusion in a viscous dusty fluid is studied and the behavior of fluid flow and heat transportation is investigated within the boundary layer over a permeable linearly stretching sheet.

Mechanical stability and insulation reliability of polymeric layers constructed by thermal fusion of polymer shell particles heterocoagulated on conductive nickel‐plated core particles

AbstractIn this study, the mechanical stability and insulating reliability of polymeric layers constructed on the surface of nickel‐plated particles for anisotropic conductive films were measured by means of a microcompression test. The polymeric layers were constructed by heterocoagulation between the nickel‐plated core particles and the polymeric shell particles and successive thermal fusion. Uniform core‐shell particles with a coverage of approximately 60%–70% were prepared at NaCl concentrations near the critical coagulation concentrations of the shell particles. Continuous polymeric layers were successfully formed by heating the heterocoagulates at a temperature slightly higher than the glass transition temperature of the shell particles. The microcompression test was applied to measure the compression displacement until the heterocoagulates were electrically connected. The larger the shell particles and the higher the coverage of heterocoagualtes, the greater the displacement, reaching a maximum displacement of 0.72 μm for heterocoagulates with shell particles of 217 nm before heating. Heating the heterocoagulates and thermally melting adjacent shell particles could further improve the insulating properties of polymeric layer. Thermal melting of shell particles of heterocoagulates with a coverage more than 60% by 152 or 217 nm shells resulted in the disappearance of zero‐point conductive particles.

Synthesis and Characterization of Chicken Bone‐Derived Hydroxyapatite Incorporating Pectin

AbstractHydroxyapatite (HA) was synthesized from chicken bone waste by calcination. Pectin was extracted from orange peels by microwave irradiation, and 1 and 3 wt % of pectin was incorporated into the HA. The resulting powders were then pressed into disk samples before being sintered at temperatures of 1050, 1150, and 1250 °C for 2 h. Various analytical techniques, including Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, density measurement, and Vickers microhardness tests, were used to evaluate the characteristics and mechanical properties of the samples. The incorporation of pectin did not interfere with the pure phases of HA, and minimal amounts of β‐tricalcium phosphate were detected in the XRD patterns. Both ball milling and the addition of pectin effectively reduced the particle size of HA. However, the addition of pectin above 1 wt % did not contribute significantly to the densification and hardness of chicken bone‐derived HA (CHA) compared with ball‐milled CHA. Samples sintered at 1050 °C had the lowest relative density, owing to incomplete particle fusion. Increasing the sintering temperature resulted in a maximum relative density of ca. 95 % and a Vickers microhardness of 4.12 GPa for ball‐milled CHA samples sintered at 1250 °C. Sintering temperature and ball milling were observed to play a more significant role in the densification and hardness of CHA compared with the addition of pectin.

Crystallization-controlled fusion mechanism of the amorphous fly ash from the Shell coal gasifier by particle sieving

The mineral in coal is transformed to the fly ash of different particle sizes during the entrained flow coal gasification, causing the ash deposition problem on the radiant syngas cooler. In this study, the fusion behavior of fly ash collected from a Shell coal gasifier was analyzed by particle sieving. Results indicated that the fusibility of amorphous fly ash was influenced by the anorthite crystallization at high temperature. The fusion process of fly ash particle was divided into the sintering stage, plateau stage, and melting stage, which were caused by the flow of the amorphous fly ash, anorthite crystallization, and anorthite melting, respectively. The high theoretical anorthite content and the low fly ash viscosity improved the anorthite crystallization reaction in the fly ash particles <45 μm, resulting in a wide plateau stage, narrow melting stage, and high ash fusion temperatures (AFTs). Therefore, the fusion behavior of fly ash particles <45 μm followed “melting-dissolution” mechanism. In contrast, the fusion of fly ash particles >45 μm belonged to the “softening-melting” mechanism for the weak anorthite crystallization behavior. The fly ash particles <45 μm may cause the serious ash deposition problems for its low viscosity.

Study of Air Pressure on Arc Ion Plating on Epoxy Resin Matrix Composites at Meter Range Working Distance

The metal film was deposited on the surface of epoxy resin based composite by arc ion plating technology. The distribution of metal ions at the interface of matrix was simulated. The growth mode of metal ions on the composite surface was analyzed. The deposition rate, surface morphology and membrane base bonding strength were investigated. The results show that the transition layer of nm level will be formed on the surface of composite materials, and the larger the sputtering energy of metal ions, the deeper the distribution on the surface of composite materials. Nucleation occurs at the junction of fiber and resin matrix, and the fusion of nucleated particles grows along the fiber boundary with the increase of deposition time, and extends to the vertical fiber direction. Finally, the particles between fibers and the particles on the boundary gradually expand and merge into layered films. The working pressure decreased, the deposition rate of metal increased, the grain size decreased, the large particles on the surface of the metal coating decreased, and the bonding strength of the film base increased.

Investigation of the atomic-level microstructural evolution of quadruple-fused α/β titanium particles during sintering

The sintering dynamics of binary particles have been extensively studied; however, the sintering behavior of multiparticles still needs further investigation because it plays a key role in many industrial processes and advanced technologies. Herein, we used molecular dynamics simulations to investigate the sintering dynamics of quadruple titanium (Ti) particles. We investigated two particle arrangement configurations of Ti particles, ααββ and αβαβ, at three sintering temperatures (900 K, 1300 K, and 2000 K) to explore the microstructural changes of Ti particles during sintering. Furthermore, we proposed a formula for calculating the fusion ratio of multiple particles. The results show that ααββ-Ti could retain its HCP structure when sintered at 1300 K and 900 K, whereas only BCC-Ti was observed after sintering at high temperatures. The effect of diffusion mechanisms was more substantial at high temperatures, and the higher the sintering temperature, the better the particle fusion effect. In addition to the effect of temperature on atomic migration, different particle arrangement configurations can impact atomic migration.

Serinc5 Restricts HIV Membrane Fusion by Altering Lipid Order and Heterogeneity in the Viral Membrane.

The host restriction factor, Serinc5, incorporates into budding HIV particles and inhibits their infection by an incompletely understood mechanism. We have previously reported that Serinc5 but not its paralogue, Serinc2, blocks HIV cell entry by membrane fusion, specifically by inhibiting fusion pore formation and dilation. A body of work suggests that Serinc5 may alter the conformation and clustering of the HIV fusion protein, Env. To contribute an additional perspective to the developing model of Serinc5 restriction, we assessed Serinc2 and Serinc5's effects on HIV pseudoviral membranes. By measuring pseudoviral membrane thickness via cryo-electron microscopy and order via the fluorescent dye, FLIPPER-TR, Serinc5 was found to increase membrane heterogeneity, skewing the distribution toward a larger fraction of the viral membrane in an ordered phase. We also directly observed for the first time the coexistence of membrane domains within individual viral membrane envelopes. Using a total internal reflection fluorescence-based single particle fusion assay, we found that treatment of HIV pseudoviral particles with phosphatidylethanolamine (PE) rescued HIV pseudovirus fusion from restriction by Serinc5, which was accompanied by decreased membrane heterogeneity and order. This effect was specific for PE and did not depend on acyl chain length or saturation. Together, these data suggest that Serinc5 alters multiple interrelated properties of the viral membrane─lipid chain order, rigidity, line tension, and lateral pressure─which decrease the accessibility of fusion intermediates and disfavor completion of fusion. These biophysical insights into Serinc5 restriction of HIV infectivity could contribute to the development of novel antivirals that exploit the same weaknesses.

Packaging and Uncoating of CRISPR/Cas Ribonucleoproteins for Efficient Gene Editing with Viral and Non-Viral Extracellular Nanoparticles

Rapid progress in gene editing based on clustered regularly interspaced short palindromic repeats/CRISPR-associated protein (CRISPR/Cas) has revolutionized functional genomic studies and genetic disease correction. While numerous gene editing applications have been easily adapted by experimental science, the clinical utility of CRISPR/Cas remains very limited due to difficulty in delivery to primary cells and possible off-target effects. The use of CRISPR in the form of a ribonucleoprotein (RNP) complex substantially reduces the time of DNA exposure to the effector nuclease and minimizes its off-target activity. The traditional electroporation and lipofection methods lack the cell-type specificity of RNP delivery, can be toxic for cells, and are less efficient when compared to nanoparticle transporters. This review focuses on CRISPR/Cas RNP packaging and delivery using retro/lentiviral particles and exosomes. First, we briefly describe the natural stages of viral and exosomal particle formation, release and entry into the target cells. This helps us understand the mechanisms of CRISPR/Cas RNP packaging and uncoating utilized by the current delivery systems, which we discuss afterward. Much attention is given to the exosomes released during viral particle production that can be passively loaded with RNPs as well as the mechanisms necessary for particle fusion, RNP release, and transportation inside the target cells. Collectively, together with specific packaging mechanisms, all these factors can substantially influence the editing efficiency of the system. Finally, we discuss ways to improve CRISPR/Cas RNP delivery using extracellular nanoparticles.

Модель формування пористості брикетів губчастого титану на стадії спікання

This article examines the peculiarities of the formation of interparticle connections in porous products based on titanium powders using sponge titanium as an example, which are used in the aviation industry and airfield management. The developed model is based on the results of a previous study, where the structure of cuboctahedral and inverse cuboctahedral clusters of packing spherical powder particles was determined at the most dense packing. During the study, a model of the fusion of particles at the points of pressing deformation due to recrystallization under the influence of high temperatures in a vacuum was developed. 4 main stages of powder briquette sintering were considered, and a mathematical model was developed for each of them. Thus, the stage of liquid evaporation is considered from the viewpoint of the cavitation effect of boiling on the surface of particles and boiling of plasticizers. Euler's film boiling formula was used to describe the forces acting on the particle surface; Tolubinsky's formula was used for bubble boiling; convective heat exchange was considered part of the final stage of sintering. The stage of the formation of metallic bonds is modeled on the basis of the results of practical studies in the REV 5.5 furnace, recrystallization based on differential scanning colorimetry on the NETZSCH STA 449F1 Proteus device, and determining the change in grain size according to the E19 ASTM scales using the Jeffers method. The diffusion stage is modeled on the basis of the approximation of the particle deformation model in the contact zones at the pressing stage using the Frenkel formula. Linear shrinkage is modeled based on direct measurement of sample sizes before and after sintering. The developed model has a certain versatility when applied to simulate the interaction of particles of metal powders under the conditions of the formation of porous briquettes, especially if the shape of the particles is close to round or spongy. The obtained result will make it possible to more accurately evaluate such a factor as the adhesion between the particles of the pressing and predict the tensile strength of the material. Additionally, due to the mathematical characterization of the peculiarities of the formation of corpuscular porosity under the conditions of sintering in a vacuum, we can design materials with differentiated porosity, as well as lay the foundations for powder 3D printing of such materials, by assembling grain by grain, or layer by layer with the adjustment of the force of particle compression one into the other.

Distributed thermometry for superconducting magnets using non-leaky acoustic waveguides

Distributed temperature sensing is the preferred approach for detecting and localizing normal zones in the high-field magnets of particle accelerators and fusion energy systems based on high-temperature superconductors. Optical fibers show promise in realizing this approach but suffer from known drawbacks, such as fiber fragility and cross-sensitivity to strain. Guided acoustic wave-based thermometry is a viable alternative to fiber optics; however, its application is currently limited by the leaky nature of wave propagation in acoustic waveguides. We propose the novel concept of a cladded acoustic waveguide in which, due to the elimination of the adhesion between the core and cladding, propagation of longitudinal acoustic excitations is sustained over long distances without leaking wave energy to the environment. These acoustic fibers can be structurally integrated into superconducting magnets and enable the distributed detection of local heating via thermally driven variations in the sound velocity. We present the practical design of acoustic fibers and the results of the experimental detection and localization of heat sources using our technique under ambient and cryogenic conditions. The prospects of using this technique for superconducting magnet quench diagnostics are discussed.