Cavity Design Research Articles

A Broadband Mechanically-Tuned Superconducting Cavity Design Suitable for the Fermilab Main Injector

A Broadband Mechanically-Tuned Superconducting Cavity Design Suitable for the Fermilab Main Injector

Impact of Conservative Access Cavity Designs and Remaining Tooth Structure on Fracture Resistance of Maxillary First Premolars(In Vitro Study)

Impact of Conservative Access Cavity Designs and Remaining Tooth Structure on Fracture Resistance of Maxillary First Premolars(In Vitro Study)

Reciprocation and rotation nickel-titanium file systems’ cyclic fatigue and centering ability in premolars accessed by ultraconservative and traditional access cavities: An in vitro study

Introduction: With the importance of restricted access cavities, this study aimed to compare the cyclic fatigue and the centering ability of TruNatomy rotary file versus R-motion reciprocating file systems in premolars accessed by traditional versus ultraconservative access cavity preparations. Materials and Methods: Forty extracted intact maxillary first premolars were divided into two groups (n = 20/group) according to the access cavity design (traditional or ultraconservative). Each group was then subdivided according to the type of file used for instrumentation (TruNatomy [26/0.04] or R-motion [30/0.04] [n = 10 teeth/subgroup]). Cone-beam computed tomography (CBCT) scans were obtained for all the teeth before and after instrumentation. The teeth were accessed and instrumented by three in-and-out pecking motions repeated two times until the instrument reached the working length. Every instrument was only used to prepare one canal. For cyclic fatigue assessment, the used files, in addition to 10 brand-new TruNatomy and R-motion files that were used as control groups, were tested in stainless-steel artificial canals, and the time to fracture was used to determine the number of cycles to fracture (NCF). After obtaining and analyzing the before and after instrumentation CBCT images, the centering ability of the buccal roots was calculated at 3, 5, and 7 mm from the apex. Data were statistically analyzed. Results: There were no differences in NCF and centering ability of each file in both access cavities (P > 0.05). There were higher NCF values of the R-motion file compared to the TruNatomy file (P < 0.05). The R-motion file showed significantly higher centering than the TruNatomy file in the traditional access cavity at the 3 and 5 mm levels and the 3 mm level in the ultraconservative access cavity (P < 0.05). Conclusion: The R-motion file had significantly higher cyclic fatigue resistance and centering ability than the TruNatomy file. The ultraconservative access cavity had no unfavorable influence on the cyclic fatigue resistance and the centering ability of R-motion and TruNatomy files.

Fracture Resistance of Premolars Restored with Inlay/Onlay Composite and Lithium Disilicate CAD/CAM Block Restorations (An In Vitro Study)

Aim: To assess the fracture resistance of Premolars restored with inlay and onlay composite and E-max CAD/CAM block restoration.
 Material and method: Randomly, fifty maxillary premolar teeth were separated into three major groups: The first group was left unaltered (control group), while the other two groups were prepared with inlay and onlay cavities and restored with lithium disilicate blocks (IPS E.max CAD) and ceramic blocks (Cerasmart). Restorations were bonded using adhesive resin cement (RelyX Ultimate). All samples were thermocycling 500 cycles, between 5 to 55°C, and the cycle time was set at the 30s. The specimen was undergone compressive axial loading in a universal testing machine till the fracture occurred. The result was analyzed using one-way ANOVA, and LSD tests with a significance level set at 0.05.
 Result: There were no significant differences in means between the control group and the inlay groups that were restored with Emax and Cerasmart (P >.05).but, the control group has significantly higher means than onlay groups restored with Emax and Cerasmart (P< .05). The two materials show comparable results in both designs.
 Conclusion: The fracture resistance of inlay-prepared teeth showed comparable strength to the intact teeth. Conversely, the fracture resistance of onlay-prepared teeth is comparatively lower than intact teeth. The two materials show comparable results irrespective of cavity design.

Wavelength-stabilized figure-of-9 thulium-doped all-fiber laser emitting 560 fs pulses

We demonstrate a figure-of-9 all-fiber thulium-doped laser (TDFL) that generates 560 fs long pulses at 1948 nm wavelength. In order to achieve self-starting passive mode-locking, we utilize an in-fiber Faraday rotator to induce a nonreciprocal phase shift. To the best of our knowledge, this is the first all-fiber TDFL that combines an artificial saturable absorber (SA) with a chirped fiber Bragg grating (CFBG) as a wavelength-selective reflector. This cavity design is an excellent candidate to pump nonlinear processes such as supercontinuum and frequency comb generation since it does not require any SA material that degrades over time for mode-locking and could be made wavelength-tuneable via the CFBG.

Prompt Analysis and Design for Passively Mode-Locked Solid-State Lasers with Semiconductor Saturable Absorbers

The critical pump power for achieving passively continuous-wave mode-locking in a solid-state laser is analytically derived from the spatially dependent rate equations and the criterion for the intracavity pulse energy. A prompt way is proposed to straightforwardly design the cavity for passively mode-locked solid-state lasers. Complete experiments are performed to demonstrate the proposed cavity design and, simultaneously, to verify the theoretical model for the critical pump powers. It is interestingly observed that even though a larger modulation depth causes a higher critical pump power, it can generate a shorter pulse width in return.

Biomechanical performance of resin composite on dental tissue restoration: A finite element analysis.

This study investigates the biomechanical performance of various dental materials when filled in different cavity designs and their effects on surrounding dental tissues. Finite element models of three infected teeth with different cavity designs, Class I (occlusal), Class II mesial-occlusal (MO), and Class II mesio-occluso-distal (MOD) were constructed. These cavities were filled with amalgam, composites (Young's moduli of 10, 14, 18, 22, and 26 GPa), and glass carbomer cement (GCC). An occlusal load of 600 N was distributed on the top surface of the teeth to carry out simulations. The findings revealed that von Mises stress was higher in GCC material, with cavity Class I (46.01 MPa in the enamel, 23.61 MPa in the dentin), and for cavity Class II MO von Mises stress was 43.64 MPa, 39.18 MPa in enamel and dentin respectively, while in case of cavity Class II MOD von Mises stress was 44.67 MPa in enamel, 27.5 in the dentin. The results showed that higher stresses were generated in the non-restored tooth compared to the restored one, and increasing Young's modulus of restorative composite material decreases stresses in enamel and dentin. The use of composite material showed excellent performance which can be a good viable option for restorative material compared to other restorative materials.

Comparative Evaluation of Different Endodontic Access Cavity Designs with Different Burs-An in vitro Experimental Insight into the Aspect of Fracture Resistance.

In vitro fracture resistance of extracted mandibular molars treated with various access cavity designs, including traditional endodontic cavity (TradAC), conservative/contracted endodontic cavity (ConsAC), ninja endodontic cavity (UltraAC), truss endodontic cavity (TrussAC), caries-driven access cavity (CariesAC), and intact teeth, is the focus of this study. Six groups of 20 mandibular molars, totaling 120, were used in the investigation. While the other five groups underwent various access cavity preparations, chemomechanical preparation, and obturation procedures before being repaired with composite resin, Group 1 was left unaltered (the control). A 6 mm round head tip was used to apply the fracture force, which was measured in newtons, at a crosshead speed of 1 mm/min until fracture developed. According to the current study, the intact control group had the maximum fracture resistance. The access cavity groups' mean values were maximum in CariesAC followed by ConsAC, TrussAC, UltraAC, and TraditonalAC respectively. While among the four minimally invasive designs, CariesAC showed a higher fracture resistance despite the results being statistically insignificant, TradAC had a significantly lower resistance than other conservative access cavity designs.

Comparison of Different Endodontic Access Cavity Designs on the Fracture Resistance of Tooth in WaveOne Gold and TruNatomy Instrumentation.

An important aspect of the preparation of the access cavity and biomechanical preparation of the root canal is to safeguard as much of the tooth's framework as possible without affecting access and visibility. To compare the impact of the conservative design of access preparation and traditional design of access preparation in association with TruNatomy endodontic instrumentation and WaveOne Gold endodontic instrumentation on resistance to fracture by the design of a cavity for endodontic access using finite element analysis. Micro-CT radiographic images of 16 human first permanent molars of the mandible were included in the study to create representative finite element analysis computational models. A significant reduction in load for failure after endodontic preparation was observed in TDAP subcategories as compared to specimens with CDAP. However, the reduction in load for failure was comparable in both endodontic instrument systems within the CDAP and TDAP. A significant reduction in load for failure after endodontic preparation was observed in the traditional design of access preparation subcategories as compared to specimens with the conventional design of access preparation.

Ag-cap-enhanced upconversion luminescence of micropillars with unidirectional radiation

Exploration of plasmonic structures to enhance upconversion luminescence (UCL) attracts attention because faint UCL from a material is a bottleneck for its applications. We designed and prepared three easily realized structures to improve the UCL of β-NaYF4:Yb3, Er3+ micropillar (MP), and compared them to a reference structure on glass on single particles. We achieved a 43-fold UCL enhancement with the MPs with an Ag cap.The experimental results and simulations indicated that the improvements in excitation field and radiation direction collectively enhanced the MP UCL. We validated the captured radiation patterns generated from various structures by excitation simulations and provide a rational criterion for cavity design.

Q-switched erbium-doped fiber lasers with ITO thin film saturable absorbers: A comprehensive cavity configuration study

This study presents the utilization of an indium tin oxide (ITO) thin film as a saturable absorber (SA) in various cavity configurations to illustrate a Q-switched erbium-doped fiber laser (EDFL). The system is designed in three distinct configurations, including linear, single-ring, and Figure-8 cavities, by integrating ITO in the setup, which has a modulation depth of 48.04 %. The research findings highlight that the single-ring cavity design has better performance over linear and Figure-8 designs in terms of Q-switched EDFL performance. The advantage of the single-ring cavity design is demonstrated by the higher values of the repetition rate and signal-to-noise ratio, which are 37.60 kHz and 57.45 dB, respectively. Subsequently, this single-ring cavity can be employed in applications of tunable, switchable dual-wavelength systems and optical fiber sensing.

Optical Cavity Design and Functionality for Molecular Strong Coupling.

Optical cavity/molecule strong coupling offers attractive opportunities to modulate photochemical or photophysical processes. When atoms or molecules are placed in an optical cavity, they can coherently exchange photonic energy with optical cavity vacuum fields, entering the strong coupling interaction regime. Recent work suggests that the thermodynamic and kinetic properties of molecules can be significantly changed by strong coupling, resulting in the emergence of intriguing photochemical and photophysical phenomena. As more and more physico-chemical systems are studied under strong coupling conditions, optical cavities have also advanced in their sophistication, responsiveness, and (multi)functionality. In this review, we highlight some of these recent developments, particularly focusing on Fabry-Perot microcavities.

Bragg Grating Cavity Design Using Bragg Gratings

The aim of the experiment is to design Bragg Grating Cavity design (to show Fabry Perot effects) for High Quality Factor. The basic Bragg Grating design used in this project consists of two identical Bragg Gratings and a cavity between the two Gratings. Bragg devices are first simulated using Transfer Matrix Model (TMM) on MATLAB. Parameters like Number of Grating Periods, Cavity Length and Type of Grating are varied to note the effect on Quality Factor. 7 Bragg devices are then designed using KLayout, visualized using Lumerical Interconnect and compared to Matlab TMM model. Simulated results are compared to Measured results using MATLAB and the differences between measurement data and simulated data are discussed. Out of the several implemented designs, the rectangular grating type design with Grating periods of 195, cavity length of 54.6μm and corrugation width 0.045μm resulted in the highest experimental Quality Factor.

Multi-Physics and Multi-Objective Optimization for Fixing Cubic Fabry–Pérot Cavities Based on Data Learning

The Fabry–Pérot (FP) cavity is the essential component of an ultra-stable laser (USL) for gravitational wave detection, which couples multiple physics fields (optical/thermal/mechanical) and requires ultra-high precision. Aiming at the deficiency of the current single physical field optimization, a multi-physics and multi-objective optimization method for fixing the cubic FP cavity based on data learning is proposed in this paper. A multi-physics coupling model for the cubic FP cavity is established and the performance is obtained via finite element analysis. The key performance indices (V, wF, wF) and key design variables (d, l, F) are determined considering the features of the FP cavity. Different data learning models (NN, RSF, KRG) are established and compared based on 49 sets of data acquired by orthogonal experiments, with the results showing that the neural network has the best performance. NSGA-II is adopted as the optimization algorithm, the Pareto optimal front is obtained, and the optimal combination of design variables is finally determined as {5,32,250}. The performance after optimization proves to be greatly improved, with the displacement under the fixing force and vibration test both decreased by more than 60%. The proposed optimization strategy can help in the design of the FP cavity, and could enlighten other optimization fields as well.

Monolithic Polarizing Circular Dielectric Gratings on Bulk Substrates for Improved Photon Collection from InAs Quantum Dots.

III-V semiconductor quantum dots (QDs) are near-ideal and versatile single-photon sources. Because of the capacity for monolithic integration with photonic structures as well as optoelectronic and optomechanical systems, they are proving useful in an increasingly broad application space. Here, we develop monolithic circular dielectric gratings on bulk substrates - as opposed to suspended or wafer-bonded substrates - for greatly improved photon collection from InAs quantum dots. The structures utilize a unique two-tiered distributed Bragg reflector (DBR) structure for vertical electric field confinement over a broad angular range. Opposing "openings" in the cavities induce strongly polarized QD luminescence without harming collection efficiencies. We describe how measured enhancements depend on the choice of collection optics. This is important to consider when evaluating the performance of any photonic structure that concentrates farfield emission intensity. Our cavity designs are useful for integrating QDs with other quantum systems that require bulk substrates, such as surface acoustic wave phonons.

Influence of different access cavity sizes on the direction of stress distribution in endodontically treated uniradicular maxillary premolar

Objective: This study aimed to evaluate the influence of different access cavity sizes on the stress distribution in an endodontically treated maxillary premolar model compared to an intact one using finite element analysis (FEA). Materials and Methods: The distributions of maximum and minimum principal stress were calculated. In the intact tooth, the maximum principal stress was located in the enamel-dentine junction and the minimum principal stress was in the cervical area. Results: In large-sized access, the maximum principal stress (tensile) increased by 41% compared to the contracted access model. This tensile strength was concentrated on interface tooth/restoration. Medium-sized access caused an increase of 27% of the minimum principal stress(compressive strength) on the apical region compared to the contracted access cavity. There was also an increase of 15% of the maximum principal stress (tensile strength) when comparing medium and minimum-sized cavities. Conclusion: The endodontic access cavity design modified the value and the direction of principal stress distribution of endodontically treated uniradicular maxillary premolar compared to the natural one.

Design, fabrication, and characterization of a drift tube linac type double gap re-buncher cavity.

The Low Energy High Intensity Proton Accelerator (LEHIPA) at Bhabha Atomic Research Centre, India, has recently been commissioned to the target energy of 20MeV by beam acceleration through a 352MHz radio frequency quadrupole (RFQ) and drift tube linac (DTL). The medium energy beam transport (MEBT) line of LEHIPA matches the 3MeV beam from RFQ to the DTL using four electromagnetic quadrupoles and a re-buncher cavity. In the beam transport lines of high frequency linacs, TM010 mode single gap buncher cavities are conventionally used, while a double gap re-buncher cavity was chosen for the short length LEHIPA MEBT based on beam dynamics simulations. The 352MHz double gap re-buncher cavity has been designed in a DTL type geometry with a cell length of βλ. This double gap cavity is found to be more power efficient with a higher shunt impedance and transit time factor than the conventional single gap buncher cavity. Electromagnetic design simulations, fabrication details, low power and high-power RF test results, and beam test results of the re-buncher cavity are presented in this paper.

Design of MW-Class Coaxial Gyrotron Cavities With Mode-Converting Corrugation Operating at the Second Cyclotron Harmonic

Design of MW-Class Coaxial Gyrotron Cavities With Mode-Converting Corrugation Operating at the Second Cyclotron Harmonic

Impact of Access Cavity Design and Root Canal Taper on Fracture Strength of Endodontically Treated Mandibular Premolars (An In-Vitro Study)

Impact of Access Cavity Design and Root Canal Taper on Fracture Strength of Endodontically Treated Mandibular Premolars (An In-Vitro Study)

Resonance cavity as an education tool in PlasmaLab@CTU

PlasmaLab@CTU is a laboratory at the Czech Technical University in Prague dedicated to train new fusion physicists and engineers in plasma physics and technology with focus on the plasma diagnostics. The resonance cavity is one of the devices which train students in handling microwaves together with vacuum and plasma physics. The contribution will present the design of the resonance cavity, and measurements of the density as the function of the pressure in different gases. It will also present this experiment as an educational tool for the fusion community.The resonance cavity is a metal cylinder placed inside a glass container. It can be evacuated via holes in the top lid. Plasma is generated between an electrode inserted inside and the cylinder itself by RF source with the frequency of 13.5 MHz, and the power of roughly 70 W. Two antennas are placed inside the resonator in the bottom lid to launch and measure the resonant modes in the cavity. Plasma density can be estimated from the shift of the resonance peaks with/without plasma.The experiment can operate with five gases. It can be remotely controlled via its own interface through the internet. The remote control is an important feature of the PlasmaLab@CTU. It aims in continuing in the tradition of educational events already established by the GOLEM tokamak.