62 research outputs found
Response analysis and modeling of high temperature superconductor edge transition bolometers
No full textOne of the promising devices made of high temperature superconducting (HTSC) materials are edge transition bolometers. Since the discovery of high-temperature superconductors, many works have been focused on the application of these materials in different types of bolometers for the near to far infrared wavelength regime [l]-[9]. They can be used to detect electromagnetic radiation over the whole spectrum from x-ray to the far-infrared [1], [9]-[13]. The superconductor bolometers typically consist of patterned thin or thick superconducting films deposited on crystalline substrates such as MgO, SrTiO3, and LaA103. Their operation is based upon their steep drop in the resistance, R, at their transition temperature, Tc. The detector is typically held at a temperature close to the middle of the superconducting transition, where the dR/dT is maximum. When the detector is illuminated its temperature rises by an amount proportional to the input radiation power resulting in a ΔR. The response obtained by the above mechanism is the so called the bolometric, or equilibrium response, as opposed to typically faster non-bolometric or intrinsic response caused by other mechanisms such as direct depairing. A typical response of an YBCO sample versus temperature at low frequencies is shown in Figure 1.1
Analytic modeling of patterned high-T c superconductive bolometers: film and substrate interface effects
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Analytic modeling of patterned high-Tc superconductive bolometers: film and substrate interface effects
No full textDate of Conference: 19-24 July 1998Conference Name: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1998Superconducting film and substrate interface effects on the response of superconductive edge-transition bolometers are modeled with a one dimensional thermal model in closed form, for samples with large area patterns compared to the substrate thickness. The results from the model agree with experimental results on samples made of meander line patterned granular YBCO films on crystalline substrates, in both the magnitude and phase of the response versus modulation frequency up to about 100 KHz, the limit of the characterization setup. Using the fit of the calculated frequency response curves obtained from the model to the measured ones, values of the film-substrate and substrate-holder thermal boundary resistance, heat capacity of the superconducting film, and the thermal parameters of the substrate materials could be investigated. While the calculated magnitude and phase of the response of the SrTiO3 substrate samples obtained from the model is in a very good agreement with the measured values, the calculated response of the LaAlO3 and MgO substrate samples deviate slightly from the measured values at very low frequencies, increasing with an increase in the thermal conductivity of the substrate material. Using the fit of the calculated response to the measured values, film-substrate thermal boundary resistances in the range of 4.4* 10-3 to 4.4* 10-2 K-cm2-w-1 are obtained for different substrate materials. The effect of substrate optical absorption in the response of the samples is also investigated
Mechanical force optimization on superconductor element of shield-type superconducting FCLs
No full textFlux-Based Modeling of Inductive Shield-Type High-Temperature Superconducting Fault Current Limiter for Power Networks
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A novel method of flat YBCO rings development for shield-type superconducting fault current limiters fabrication
No full textSheathless Dielectrophoresis-Based Microfluidic Chip for Label-Free Bio-Particle Focusing and Separation
No full textThis paper presents a novel microfluidic dielectrophoresis (DEP) system to focus and separate cells of similar size based on their structural differences, which is more challenging than separation by size. Because, in this case, the DEP force is only proportional to the polarizabilities of cells, we used live and dead yeast cells as bio-particles to investigate the chip efficiency. Our designed chip consists of three sections. First, we focused on cells at the center of the microchannel by employing a negative DEP phenomenon. After that, cells were separated due to the different deflection from high-electric-field areas. Finally, a novel outlet design was utilized to facilitate separation by increasing the gap between the two groups of cells. The proposed sheath-free design has one inlet for target cell injection requiring only one pump to control the flow rate, which reduces costs and complexity. Successful discrimination of the particles was achieved by using DEP force as a label-free and highly efficient technique. As an accessible and cost-effective method, soft lithography with a 3D-printed resin mold was used to fabricate the microfluidic parts. The microchannel was made of polydimethylsiloxane (PDMS) material that is biocompatible. The electrodes were made of gold due to its biocompatibility and non-oxidation, and a titanium layer was sputtered as the buffer layer for the adhesion of the sputtered gold layer to the glass. A standard microfabrication process was employed to create the electrode pattern. O2 plasma treatment yielded leakage-free bonding between the patterned glass and PDMS structure containing the microfluidic channel. The maximum voltage applied to the electrodes (26 V) was lower than the threshold value for cell electroporation. The simulations and experimental results both confirm the effectiveness of the proposed microfluidic chip
Optimization of Argon Plasma Working Pressure through Parallel PIC Simulations for Enhancement of Material Surface Treatment
No full textIn this study, a novel method for simulating plasma dynamics using parallel programming has been developed. The equations based on Particle-in-Cell (PIC) method were utilized and adapted for this purpose. We utilized 35 processors from Sharif High Performance Computing (HPC) center and divided the plasma volume into 35 parts, with each part\u27s PIC equation solved on a separate processor. Once the computations were completed, the results from all processors were combined to form a complete plasma volume. The simulations revealed that there is an optimal pressure for argon, at which the ion flux onto the electrode surface is maximized. Increasing the absolute value of the electrode potential also increases this flux. Therefore, for a given potential, selecting the optimal pressure is crucial for the most effective surface modification using argon plasma. In this work, for applied voltage of -500 V, the optimum pressure was 100 mTorr
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