RF system challenges for future $$\hbox {e}^+ \hbox {e}^-$$ circular colliders

The RF system is the centrepiece of any future circular lepton collider. In particular, the system is required to support the high intensity beams needed for pushing the luminosity at the lower energy regimes of future energy-frontier circular lepton colliders (e.g. for operation in the Z peak and at the WW threshold). Capturing, storing the beam and replacing energy losses from synchrotron radiation demand low frequency, low shunt resistance cavities, low number of cells and high RF power per cell. Controlling the beam both transversely and longitudinally requires sophisticated beam control and timing systems. Additional RF systems are used to ensure transverse stability (feedback systems) and to increase the luminosity (crab cavities). Operation at high energies (such as the ZH and $${\mathrm{t}{\overline{\mathrm{t}}}}$$ t t ¯ threshold) requires a very large accelerating voltage, since synchrotron radiation leads to significantly higher energy losses per turn which must be compensated. Since the RF system is to be optimised in size and energy efficiency for varying demands for the different operational modes, the spectrum of R&D challenges covers a wide range of technologies.

Fast-sweeping Langmuir probes: what happens to the I-V trace when sweeping frequency is higher than the ion plasma frequency?

Limited particle transit time is one of several limiting factors which determines the maximum temporal resolution of a Langmuir probe. In this work, we have revisited known fast sweep Langmuir probe techniques in a uniform, quiescent multi-dipole confined hot cathode discharge with two operation scenarios: one in which the probe sweeping frequency fsweep is much lower than the ion plasma frequency fpi, another one where fsweep is much greater than fpi, respectively. This allows the investigation of the effect of limited ion-motion on I-V traces. Serious distortions of I-V traces at high frequencies, previously claimed to be ion-motion limitation effect, was not found in the degree previously claimed unless shunt resistance is sufficiently high, despite achieving a ratio of ~ 3 between the probe sweeping frequency and the ion plasma frequency. On the other hand, evidences of sheath capacitance on the I-V trace have been observed. Distortions of I-V traces qualitatively agrees with predictions of sheath capacitance response to the sweeping voltage. Additionally, techniques in fast sweep Langmuir probe are briefly discussed. The comparison between a High-speed dual Langmuir probe (HDLP) and the single probe setup shows that the capacitive response can be removed via subtracting a leakage current for the single probe setup almost as effective as using an HDLP setup, but the HDLP setup does remain advantageous in its facilitation of better recovery of weak current signal common in low plasma density situations.

Optimization of accurate estimation of single diode solar photovoltaic parameters and extraction of maximum power point under different conditions

Introduction. With the snowballing requirement of renewable resources of energy, solar energy has been an area of key concern to the increasing demand for electricity. Solar photovoltaic has gotten a considerable amount of consideration from researchers in recent years. Purpose. For generating nearly realistic curves for the solar cell model it is needed to estimate unknown parameters with utmost precision. The five unknown parameters include diode-ideality factor, shunt-resistance, photon-current, diode dark saturation current, and series-resistance. Novelty. The proposed research method hybridizes flower pollination algorithm with least square method to better estimate the unknown parameters, and produce more realistic curves. Methodology. The proposed method shows many promising results that are more realistic in nature, as compared to other methods. Shunt-resistance and series-resistance are considered and diode constant is not neglected in this approach that previously has been in practice. The values of series-resistance and diode-ideality factor are found using flower pollination algorithm while shunt-resistance, diode dark saturation current and photon-current are found through least square method. Results. The combination of these techniques has achieved better results compared to other techniques. The simulation studies are carried on MATLAB/Simulink.

Dye extracted from Bael leaves as a photosensitizer in dye sensitized solar cell

This study has explored a new plant source, Bael tree leaves, as an efficient dye extraction towards green energy harvesting through dye-sensitized solar cells (DSSCs). The photosensitizers, photo-absorption, bandgap, and ionic conductivity characteristics of the extracted dye were determined using thin-layer chromatography (TLC), ultraviolet-visible spectroscopy, Tauc plot, and conductivity meter, respectively. Chlorophyll is the main constituent in the extracted dye confirmed by TLC analysis. An optimum concentration (0.2 g/mL) with ionic conductivity of 455 μS/cm of the dye was used as a photoactive layer in DSSC, demonstrating power densities of 1.345 μW/m2 and 8.078 μW/m2 under the illumination of the LED lamp (1555 lx) and tungsten bulb (1926 lx), respectively. Additional parameters, including fill factor (0.26), ideality factor (1.25), characteristic resistance (309 Ω), series resistance (313 Ω), and shunt resistance (662 Ω) of the fabricated DSSCs under tungsten illumination reveal that the novel Bael tree leaves-based dye can harvest green energy efficiently through DSSCs.

Vision Analysis of the Influence of Piezoelectric Energy Harvesting on Vibration Damping of a Cantilever Beam

A cantilever beam, manufactured from a steel-carrying substrate and two patches of Macro Fiber Composite of P2 type, was a subject of laboratory research. MFC patches were glued on both sides of the carrying substrate and were parallelly connected. An experimental determination of an optimal resistance for both energy harvesting and vibration passive damping of the cantilever beam was the purpose of the conducted laboratory research. The research contained 10 experiments in which courses of the energy-harvesting process and resistive passive damping of vibration were estimated. Energy harvesting was estimated by measurements of the generated current for the given load-resistance values. Resistive passive damping of vibration was assessed by using a vision method that enabled the displacements’ measurements of 10 selected points in the beam structure for the given shunt-resistance values. Values of both load resistance and shunt resistance were chosen on the basis of analytically calculated optimal load resistance and optimal shunt resistance. On the basis of the conducted experiments, the resistance range for which both the energy-harvesting process and the vibration-damping process are most effective was determined.

Effect of parasitic resistances on CdTe solar cell and validation with datasheet of FS-6450A in Matlab/Simulink

Cadmium telluride (CdTe) is the second popular choice after silicon for the solar cell in photovoltaic (PV) technology. Among the thin-film photovoltaic panels, CdTe reaches its first position to surpass crystalline silicon PV in cheapness and confined a large space in the PV market. Before constructing CdTe PV panels its operating characteristics should be properly judged. Any solar cell being related to a high level of nonlinearity, the model parameter is to be chosen judiciously. The operating characteristics can be well considered after the model circuit parameter comes accurately. In this paper operating characteristics of a thin-film CdTe solar module is shown with the variation of series and shunt resistance. Also considering parasitic resistances, the output characteristics of the solar cell varying climate condition is shown. Validation with FS-6450A PV module and all the simulation works are done in Matlab/Simulink environment. In the end, it is concluded with possible outcomes.

Influence of Te layer on CdTe thin films and their performance on CdS/CdTe solar cells

CdTe semiconductor is an absorbent material used in “tandem” photovoltaic solar cells. This material is commonly deposited by thermal evaporation presenting electrical resistivity values about of 105 W·cm to 109 W·cm. CdTe is applied in thin solar cells as p-type layer which is in contact with metal back electrode in solar cells. In the CdTe/metal junction a Schottky barrier exits; and small number of charge carriers have enough energy to get over the barrier and cross to the metal back contact. To solve part of this problem, nanostructured Te thin films were used as intermediate layers between CdTe and metal contact. Te layers whit different physical properties were deposited on CdS/CdTe structure by thermal evaporation employing different growth parameters. The electrical parameters of CdTe solar cells were influenced by p+ Te regions. p+ Te regions used as intermediate layer with large deposition time increases the FF and VOC values from 30% to 60% and 560 mV to 730 mV respectively. Also, the electrical resistivity is reduced from 106 W·cm to 103 W·cm. In this sense, Te region implemented as nanostructure allows to reduce the series resistance from 99 W to 20 W and increases the shunt resistance from 1445 W to 4424 W; Te region as thin films demonstrated not be adequate.

Mathematical modelling for solar cell, panel and array for photovoltaic system

Renewable energy is considered as next alternative to fossil fuels and nowadays, it attracts much attention in agriculture and environmental protection. Application of solar photovoltaic system is drying and dehydration of products, heating, irrigation, greenhouse and power generation etc. Temperature and sun radiation varies nonlinearly. Power generation varies with reference to radiation and temperature in photo-voltaic (PV) system. PV characteristic is nonlinear and PV cell is the basic unit for electricity generation. To get the characteristic response of PV, it aimed to develop a solar cell/panel model and array on a platform like MATLAB. In this research paper, step by step procedure has been defined for modelling solar cell, panel, and array models of the photovoltaic system. Kyocera solar KC-200GT 200W solar panel is used as a reference model for further modelling. The PV array characteristic are simulated for different irradiance(200W/m2,400 W/m2 ,600 W/m2 ,800W/m2 ,1000W/m2)and temperature variation(25°C, 35°C, 45°C, 55°C, 75°C). The output characteristic of the reference model matches with simulated results. The output reduced when the solar irradiation reduced from 1000 to 200 W/m2. As the temperature increased, the output voltage decreases, whereas the output current increases slightly. This model would be useful for investigating the effect of different parameters like series resistance, shunt resistance, thermal voltage, solar cell temperature coefficient of short circuit current etc. It would also be useful for investigating the working parameters like temperature & radiation condition and different series and parallel combinations of panels. This modelling is useful in investigating the performance of solar arrays in different applications of solar power generation, as well as modelling provides a major role in the mounting of PV panels.

A Au/CuNiCoS4/p-Si photodiode: electrical and morphological characterization

In this present work, CuNiCoS4 thiospinel nanocrystals were synthesized by hot injection and characterized by X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HR-TEM), and energy-dispersive X-ray spectroscopy (EDS). The XRD, EDS, and HR-TEM analyses confirmed the successful synthesis of CuNiCoS4. The obtained CuNiCoS4 thiospinel nanocrystals were tested for photodiode and capacitance applications as interfacial layer between Au and p-type Si by measuring I–V and C–V characteristics. The fabricated Au/CuNiCoS4/p-Si device exhibited good rectifying properties, high photoresponse activity, low series resistance, and high shunt resistance. The C–V characteristics revealed that capacitance and conductance of the photodiode are voltage-and frequency-dependent. The fabricated device with CuNiCoS4 thiospinel nanocrystals can be employed in high-efficiency optoelectronic applications.

Optimal Extraction of Photovoltaic Cell Parameters for the Maximization of Photovoltaic Power Output Using a Hybrid Particle Swarm Grey Wolf Optimization Algorithm

Avoiding over-dependency on the oil-fired energy supply systems motivates many countries to integrate renewable energy into the existing energy supply systems. Solar Photovoltaic technology forms the most promising option for developing such a cost-effective and sustainable energy supply system. Generally, the current-voltage curve is used in the performance assessment and analysis of the Photovoltaic module. The accuracy of the equations for the curve depends on accurate cell parameters. However, the extraction of these parameters remains a complex stochastic nonlinear optimization problem. Many studies have been carried out to deal with such problem but still more researches need to be carried out to achieve a minimum error and a high accuracy. The existing researches ignored the variation in the meteorological data though it has a significant impact on the problem design. In this study, the Sample Average Approximation was employed to deal with the uncertainty and the hybrid optimization method was used to get the optimal parameters. The results showed that the Hybrid PSO-GWO produced the most optimal solution: Series resistance (1.4623), Shunt resistance(215.0000), Ideal diode factors (n1 = 0.9500, n2 = 1.6500) with a maximum PV power of 59.850W. The methodology produced realistic results since the variability is dealt with and the Hybrid PSO-GWO finds the optimal solution at a higher convergence rate.