P. Casolaro, V. Izzo, G. Giusi, N. Wyrsch, A. Aloisio
We investigated the capacitance of a forward-biased silicon pn diode using impedance spectroscopy. Despite extensive research spanning decades, no single model in the literature adequately describes the impedance behavior for bias up to the built-in voltage. By employing the 1N4007 diode as a case study, we analyzed the impedance over a wide frequency range, from 1 Hz to 1 MHz. Our analysis reveals that impedance can be effectively studied by combining two models. In both models, the depletion capacitance is assumed to be an ideal capacitor with a value independent of frequency. One model accounts for diffusion processes, while the other addresses interfacial effects, as well as potential and capacitance distributions across the junction. This approach offers valuable insights into the complex capacitance behavior of pn junctions as a function of the bias voltage. Measurements of depletion and diffusion capacitances, as well as of the diode transit time can be achieved from a set of impedance spectroscopy data.
{"title":"Modeling the diffusion and depletion capacitances of a silicon pn diode in forward bias with impedance spectroscopy","authors":"P. Casolaro, V. Izzo, G. Giusi, N. Wyrsch, A. Aloisio","doi":"10.1063/5.0230008","DOIUrl":"https://doi.org/10.1063/5.0230008","url":null,"abstract":"We investigated the capacitance of a forward-biased silicon pn diode using impedance spectroscopy. Despite extensive research spanning decades, no single model in the literature adequately describes the impedance behavior for bias up to the built-in voltage. By employing the 1N4007 diode as a case study, we analyzed the impedance over a wide frequency range, from 1 Hz to 1 MHz. Our analysis reveals that impedance can be effectively studied by combining two models. In both models, the depletion capacitance is assumed to be an ideal capacitor with a value independent of frequency. One model accounts for diffusion processes, while the other addresses interfacial effects, as well as potential and capacitance distributions across the junction. This approach offers valuable insights into the complex capacitance behavior of pn junctions as a function of the bias voltage. Measurements of depletion and diffusion capacitances, as well as of the diode transit time can be achieved from a set of impedance spectroscopy data.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
O. B. Ball, R. J. Husband, J. D. McHardy, M. I. McMahon, C. Strohm, Z. Konôpková, K. Appel, V. Cerantola, A. L. Coleman, H. Cynn, A. Dwivedi, A. F. Goncharov, H. Graafsma, L. Q. Huston, H. Hwang, J. Kaa, J.-Y. Kim, E. Koemets, T. Laurus, X. Li, H. Marquardt, A. S. J. Méndez, S. Merkel, A. Mondal, G. Morard, V. B. Prakapenka, C. Prescher, T. R. Preston, S. Speziale, S. Stern, B. T. Sturtevant, J. Sztuk-Dambietz, N. Velisavljevic, C.-S. Yoo, U. Zastrau, Zs. Jenei, H. P. Liermann, R. S. McWilliams
X-ray self-heating is a common by-product of X-ray Free Electron Laser (XFEL) techniques that can affect targets, optics, and other irradiated materials. Diagnosis of heating and induced changes in samples may be performed using the x-ray beam itself as a probe. However, the relationship between conditions created by and inferred from x-ray irradiation is unclear and may be highly dependent on the material system under consideration. Here, we report on a simple case study of a titanium foil irradiated, heated, and probed by a MHz XFEL pulse train at 18.1 keV delivered by the European XFEL using measured x-ray diffraction to determine temperature and finite element analysis to interpret the experimental data. We find a complex relationship between apparent temperatures and sample temperature distributions that must be accounted for to adequately interpret the data, including beam averaging effects, multivalued temperatures due to sample phase transitions, and jumps and gaps in the observable temperature near phase transformations. The results have implications for studies employing x-ray probing of systems with large temperature gradients, particularly where these gradients are produced by the beam itself. Finally, this study shows the potential complexity of studying nonlinear sample behavior, such as phase transformations, where biasing effects of temperature gradients can become paramount, precluding clear observation of true transformation conditions.
X 射线自热是 X 射线自由电子激光（XFEL）技术的常见副产品，会影响目标、光学器件和其他辐照材料。可以使用 X 射线束本身作为探针，对样品中的加热和诱导变化进行诊断。然而，X 射线辐照所产生的条件与推断出的条件之间的关系尚不明确，而且可能在很大程度上取决于所考虑的材料系统。在此，我们报告了一个简单的案例研究，即欧洲 XFEL 发射的 18.1 千伏的 MHz XFEL 脉冲串对钛箔进行辐照、加热和探测，利用测量的 X 射线衍射确定温度，并利用有限元分析解释实验数据。我们发现表观温度和样品温度分布之间存在复杂的关系，必须考虑到这些因素才能充分解释数据，包括光束平均效应、样品相变引起的多值温度以及相变附近可观测温度的跳跃和间隙。这些结果对采用 X 射线探测具有较大温度梯度的系统的研究具有重要意义，特别是当这些梯度是由光束本身产生的时候。最后，这项研究显示了研究非线性样品行为（如相变）的潜在复杂性，在这种情况下，温度梯度的偏差效应可能变得至关重要，从而阻碍了对真实转变条件的清晰观测。
{"title":"Measurement bias in self-heating x-ray free electron laser experiments from diffraction studies of phase transformation in titanium","authors":"O. B. Ball, R. J. Husband, J. D. McHardy, M. I. McMahon, C. Strohm, Z. Konôpková, K. Appel, V. Cerantola, A. L. Coleman, H. Cynn, A. Dwivedi, A. F. Goncharov, H. Graafsma, L. Q. Huston, H. Hwang, J. Kaa, J.-Y. Kim, E. Koemets, T. Laurus, X. Li, H. Marquardt, A. S. J. Méndez, S. Merkel, A. Mondal, G. Morard, V. B. Prakapenka, C. Prescher, T. R. Preston, S. Speziale, S. Stern, B. T. Sturtevant, J. Sztuk-Dambietz, N. Velisavljevic, C.-S. Yoo, U. Zastrau, Zs. Jenei, H. P. Liermann, R. S. McWilliams","doi":"10.1063/5.0215908","DOIUrl":"https://doi.org/10.1063/5.0215908","url":null,"abstract":"X-ray self-heating is a common by-product of X-ray Free Electron Laser (XFEL) techniques that can affect targets, optics, and other irradiated materials. Diagnosis of heating and induced changes in samples may be performed using the x-ray beam itself as a probe. However, the relationship between conditions created by and inferred from x-ray irradiation is unclear and may be highly dependent on the material system under consideration. Here, we report on a simple case study of a titanium foil irradiated, heated, and probed by a MHz XFEL pulse train at 18.1 keV delivered by the European XFEL using measured x-ray diffraction to determine temperature and finite element analysis to interpret the experimental data. We find a complex relationship between apparent temperatures and sample temperature distributions that must be accounted for to adequately interpret the data, including beam averaging effects, multivalued temperatures due to sample phase transitions, and jumps and gaps in the observable temperature near phase transformations. The results have implications for studies employing x-ray probing of systems with large temperature gradients, particularly where these gradients are produced by the beam itself. Finally, this study shows the potential complexity of studying nonlinear sample behavior, such as phase transformations, where biasing effects of temperature gradients can become paramount, precluding clear observation of true transformation conditions.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the most important issues related to the strength of metals is the strain rate sensitivity of the flow stress. In this study, an analytical model of the flow stress as a function of strain rate is derived theoretically. The model can reproduce the strain rate sensitivity of the flow stress of copper over a wide range of strain rates (up to 109 s−1) quantitatively. Our theoretical derivations indicate that the strain rate sensitivity of the flow stress, especially that above 103 s−1, is a result of both the variation of the dislocation mobility mechanism with stress and the particular stress dependence of dislocation density but is not a result of each single mechanism. In particular, the stress dependence of the dislocation density and the initial dislocation density are critical to the quantitative relation of the flow stress–strain rate at high strain rate and the strain rate threshold, under which the upturn of the flow stress occurs, respectively. Moreover, experiments with copper of different initial dislocation densities at moderate and high strain rate are performed. The strain rate threshold of the flow stress upturn observed in the experiments grows considerably as initial dislocation density increases, which is in accordance with theoretical prediction by our model.
{"title":"Revisiting the strain rate sensitivity of the flow stress of copper: Theory and experiment","authors":"Songlin Yao, Jidong Yu, Xiaoyang Pei, Kai Guo, Enling Tang, Guiji Wang, Qiang Wu","doi":"10.1063/5.0225090","DOIUrl":"https://doi.org/10.1063/5.0225090","url":null,"abstract":"One of the most important issues related to the strength of metals is the strain rate sensitivity of the flow stress. In this study, an analytical model of the flow stress as a function of strain rate is derived theoretically. The model can reproduce the strain rate sensitivity of the flow stress of copper over a wide range of strain rates (up to 109 s−1) quantitatively. Our theoretical derivations indicate that the strain rate sensitivity of the flow stress, especially that above 103 s−1, is a result of both the variation of the dislocation mobility mechanism with stress and the particular stress dependence of dislocation density but is not a result of each single mechanism. In particular, the stress dependence of the dislocation density and the initial dislocation density are critical to the quantitative relation of the flow stress–strain rate at high strain rate and the strain rate threshold, under which the upturn of the flow stress occurs, respectively. Moreover, experiments with copper of different initial dislocation densities at moderate and high strain rate are performed. The strain rate threshold of the flow stress upturn observed in the experiments grows considerably as initial dislocation density increases, which is in accordance with theoretical prediction by our model.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260243","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The unreacted equation of state (EOS) for an unreacted explosive can provide fundamental information to understand any analytical model for the shock and initiation process. Based on the Hugoniot expression in Jones–Wilkins–Lee (JWL) form derived from the Mie–Grüneisen EOS and conservation equation across the shock wave, a three-point calibrating method to determine the JWL EOS parameters for unreacted explosives was developed using intelligent algorithms and shock Hugoniot relationship of the explosives considered. The calibration method proposed utilizes the back propagation neural network to predict the nonlinear system composed of different JWL parameter sets; the genetic algorithm is then used to find the optimal solution of the JWL parameter set. Unreacted JWL EOS parameters of eight typical explosives were calibrated using the calibrating method developed, and an excellent agreement can be observed between JWL EOS and experimental p–v curves for all eight explosives selected, indicating the high accuracy of the three-point calibrating method. However, the effectiveness of the three-point calibrating method was experimentally validated with the experimental data measured from the shock tests of the dihydroxylammonium 5,5′-bitetrazole-1,1′-dioxide (TKX-50)-based explosive, where the JWL p–v curve derived from the three-point calibrating method is in good agreement with the experimental curve.
未反应炸药的未反应状态方程（EOS）可为理解冲击和起爆过程的任何分析模型提供基本信息。根据从 Mie-Grüneisen EOS 和整个冲击波守恒方程导出的琼斯-威尔金斯-李（JWL）形式的休伊特表达式，利用智能算法和所考虑的爆炸物的冲击休伊特关系，开发了一种三点校准方法，以确定未反应爆炸物的 JWL EOS 参数。所提出的校准方法利用反向传播神经网络预测由不同 JWL 参数集组成的非线性系统，然后利用遗传算法找到 JWL 参数集的最优解。利用所开发的校准方法对八种典型炸药的未反应 JWL EOS 参数进行了校准，结果表明所选八种炸药的 JWL EOS 与实验 p-v 曲线之间具有极好的一致性，表明三点校准法具有很高的准确性。不过，三点校准法的有效性要通过实验验证，实验数据来自 5,5′-二羟基四唑-1,1′-二氧化物（TKX-50）基二羟基铵炸药的冲击试验，三点校准法得出的 JWL p-v 曲线与实验曲线吻合良好。
{"title":"Calibration of Jones–Wilkins–Lee equation of state for unreacted explosives with shock Hugoniot relationship and optimization algorithm","authors":"Hao Cui, Junan Wu, Yuxin Xu, Hao Zhou, Rui Guo","doi":"10.1063/5.0230362","DOIUrl":"https://doi.org/10.1063/5.0230362","url":null,"abstract":"The unreacted equation of state (EOS) for an unreacted explosive can provide fundamental information to understand any analytical model for the shock and initiation process. Based on the Hugoniot expression in Jones–Wilkins–Lee (JWL) form derived from the Mie–Grüneisen EOS and conservation equation across the shock wave, a three-point calibrating method to determine the JWL EOS parameters for unreacted explosives was developed using intelligent algorithms and shock Hugoniot relationship of the explosives considered. The calibration method proposed utilizes the back propagation neural network to predict the nonlinear system composed of different JWL parameter sets; the genetic algorithm is then used to find the optimal solution of the JWL parameter set. Unreacted JWL EOS parameters of eight typical explosives were calibrated using the calibrating method developed, and an excellent agreement can be observed between JWL EOS and experimental p–v curves for all eight explosives selected, indicating the high accuracy of the three-point calibrating method. However, the effectiveness of the three-point calibrating method was experimentally validated with the experimental data measured from the shock tests of the dihydroxylammonium 5,5′-bitetrazole-1,1′-dioxide (TKX-50)-based explosive, where the JWL p–v curve derived from the three-point calibrating method is in good agreement with the experimental curve.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260239","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
N-type carbon nanotubes (CNTs)-based field-effect transistors (FETs) have huge potential applications in low-power consumption tunnel FETs. However, the low-work function metal electrodes can achieve n-type CNTs, but they are easily oxidized due to poor environmental stability. Therefore, based on first-principles calculations, we proposed halide perovskite nanowires Cs4MX5 (M = Pb, Sn; X = Cl, Br, I) inner filling to achieve n-type single-walled CNTs (SWCNTs). The results indicated that all the perovskite nanowires located at the center of the SWCNTs possess high stability. Moreover, the diameter of SWCNTs is a crucial factor affecting the inner filling of perovskite nanowires with an optimal diameter of about 1.4 nm. Furthermore, all the perovskite nanowires Cs4MX5 are excellent electron donors, and the largest charge transfer is up to 1.72 e/nm for Cs4SnI5. Their interaction mechanism reveals that the low work function and the large internal bandgap are two important factors for cubic-phase nanowires to realize the n-type CNTs. Our findings provide some candidate materials and a feasible way to achieve n-type CNTs for applying CNTs-based FETs.
基于 N 型碳纳米管（CNT）的场效应晶体管（FET）在低功耗隧道 FET 中具有巨大的应用潜力。然而，低功函数金属电极可以实现 N 型 CNT，但由于环境稳定性差，很容易被氧化。因此，我们在第一原理计算的基础上，提出了卤化物包晶纳米线 Cs4MX5（M = Pb、Sn；X = Cl、Br、I）内部填充来实现 n 型单壁 CNT（SWCNT）。结果表明，位于 SWCNT 中心的所有过氧化物纳米线都具有很高的稳定性。此外，SWCNTs 的直径是影响包晶纳米线内部填充的关键因素，其最佳直径约为 1.4 nm。此外，所有的包晶纳米线 Cs4MX5 都是出色的电子供体，其中 Cs4SnI5 的最大电荷转移量高达 1.72 e/nm。它们的相互作用机理揭示了低功函数和大内带隙是立方相纳米线实现 n 型 CNT 的两个重要因素。我们的发现为应用基于 CNTs 的 FET 提供了一些候选材料和实现 n 型 CNTs 的可行方法。
{"title":"Realizing n-type carbon nanotubes via halide perovskite nanowires Cs4MX5 inner filling","authors":"Sisi Cao, Qiyao Yang, Juexian Cao, Wangping Xu","doi":"10.1063/5.0225284","DOIUrl":"https://doi.org/10.1063/5.0225284","url":null,"abstract":"N-type carbon nanotubes (CNTs)-based field-effect transistors (FETs) have huge potential applications in low-power consumption tunnel FETs. However, the low-work function metal electrodes can achieve n-type CNTs, but they are easily oxidized due to poor environmental stability. Therefore, based on first-principles calculations, we proposed halide perovskite nanowires Cs4MX5 (M = Pb, Sn; X = Cl, Br, I) inner filling to achieve n-type single-walled CNTs (SWCNTs). The results indicated that all the perovskite nanowires located at the center of the SWCNTs possess high stability. Moreover, the diameter of SWCNTs is a crucial factor affecting the inner filling of perovskite nanowires with an optimal diameter of about 1.4 nm. Furthermore, all the perovskite nanowires Cs4MX5 are excellent electron donors, and the largest charge transfer is up to 1.72 e/nm for Cs4SnI5. Their interaction mechanism reveals that the low work function and the large internal bandgap are two important factors for cubic-phase nanowires to realize the n-type CNTs. Our findings provide some candidate materials and a feasible way to achieve n-type CNTs for applying CNTs-based FETs.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. E. García Redondo, N. A. Müller, J. M. Salum, L. P. Ferreyro, J. D. Bonilla-Neira, J. M. Geria, J. J. Bonaparte, T. Muscheid, R. Gartmann, A. Almela, M. R. Hampel, A. E. Fuster, L. E. Ardila-Perez, M. Wegner, M. Platino, O. Sander, S. Kempf, M. Weber
The Microwave SQUID Multiplexer (μMUX) is the device of choice for the readout of a large number of low-temperature detectors in a wide variety of experiments within the fields of astronomy and particle physics. While it offers large multiplexing factors, the system noise performance is highly dependent on the cold- and warm-readout electronic systems used to read it out, as well as the demodulation domain and parameters chosen. In order to understand the impact of the readout systems in the overall detection system noise performance, first, we extended the available μMUX simulation frameworks, including additive and multiplicative noise sources in the probing tones (i.e., phase and amplitude noise), along with the capability of demodulating the scientific data, either in the resonator’s phase or the scattering amplitude. Then, considering the additive noise as a dominant noise source, the optimum readout parameters to achieve minimum system noise were found for both open-loop and flux-ramp demodulation schemes in the aforementioned domains. Later, we evaluated the system noise sensitivity to multiplicative noise sources under the optimum readout parameters. Finally, as a case study, we evaluated the optimal demodulation domain and the expected system noise level for a typical software-defined radio readout system. This work leads to an improved system performance prediction and noise engineering based on the available readout electronics and the selected demodulation domain.
{"title":"Optimal demodulation domain for microwave SQUID multiplexers in presence of readout system noise","authors":"M. E. García Redondo, N. A. Müller, J. M. Salum, L. P. Ferreyro, J. D. Bonilla-Neira, J. M. Geria, J. J. Bonaparte, T. Muscheid, R. Gartmann, A. Almela, M. R. Hampel, A. E. Fuster, L. E. Ardila-Perez, M. Wegner, M. Platino, O. Sander, S. Kempf, M. Weber","doi":"10.1063/5.0222656","DOIUrl":"https://doi.org/10.1063/5.0222656","url":null,"abstract":"The Microwave SQUID Multiplexer (μMUX) is the device of choice for the readout of a large number of low-temperature detectors in a wide variety of experiments within the fields of astronomy and particle physics. While it offers large multiplexing factors, the system noise performance is highly dependent on the cold- and warm-readout electronic systems used to read it out, as well as the demodulation domain and parameters chosen. In order to understand the impact of the readout systems in the overall detection system noise performance, first, we extended the available μMUX simulation frameworks, including additive and multiplicative noise sources in the probing tones (i.e., phase and amplitude noise), along with the capability of demodulating the scientific data, either in the resonator’s phase or the scattering amplitude. Then, considering the additive noise as a dominant noise source, the optimum readout parameters to achieve minimum system noise were found for both open-loop and flux-ramp demodulation schemes in the aforementioned domains. Later, we evaluated the system noise sensitivity to multiplicative noise sources under the optimum readout parameters. Finally, as a case study, we evaluated the optimal demodulation domain and the expected system noise level for a typical software-defined radio readout system. This work leads to an improved system performance prediction and noise engineering based on the available readout electronics and the selected demodulation domain.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Planar laser-induced fluorescence (PLIF) is a crucial spectroscopic technique for measuring minor species [e.g., hydroxyl (OH), methylene (CH), and nitric oxide (NO) radicals] in combustion research, owing to its non-intrusive nature and high sensitivity. However, laser energy attenuation due to absorption poses significant challenges to its application under high-pressure conditions, which may cause asymmetric image intensity distribution along the light propagation direction. An absorption correction method for OH PLIF based on the concept of maximum number density is proposed in the present study. This method offers several key advantages, including simplicity, high accuracy, and versatility, allowing for correcting both time-averaged and instantaneous OH PLIF images. OH PLIF data obtained from a centrally staged combustor at elevated pressures (i.e., 0.3, 0.6, and 1.0 MPa) are utilized to validate the method. Correction for the time-averaged PLIF images achieves a much more symmetric distribution of OH, revealing the overall flame structures that would not have been completely visualized from the original images. The fronts of the pilot and main stage flames have also been recovered from the corrected instantaneous images. This correction algorithm provides an effective way of enhancing data quality for high-cost OH PLIF measurements at pressurized conditions.
{"title":"Laser absorption correction for hydroxyl planar laser induced fluorescence measurements in a centrally staged combustor at elevated pressures","authors":"Kexin Ji, Xin Hui, Chao Tao, Xin Xue, Qiang An","doi":"10.1063/5.0228168","DOIUrl":"https://doi.org/10.1063/5.0228168","url":null,"abstract":"Planar laser-induced fluorescence (PLIF) is a crucial spectroscopic technique for measuring minor species [e.g., hydroxyl (OH), methylene (CH), and nitric oxide (NO) radicals] in combustion research, owing to its non-intrusive nature and high sensitivity. However, laser energy attenuation due to absorption poses significant challenges to its application under high-pressure conditions, which may cause asymmetric image intensity distribution along the light propagation direction. An absorption correction method for OH PLIF based on the concept of maximum number density is proposed in the present study. This method offers several key advantages, including simplicity, high accuracy, and versatility, allowing for correcting both time-averaged and instantaneous OH PLIF images. OH PLIF data obtained from a centrally staged combustor at elevated pressures (i.e., 0.3, 0.6, and 1.0 MPa) are utilized to validate the method. Correction for the time-averaged PLIF images achieves a much more symmetric distribution of OH, revealing the overall flame structures that would not have been completely visualized from the original images. The fronts of the pilot and main stage flames have also been recovered from the corrected instantaneous images. This correction algorithm provides an effective way of enhancing data quality for high-cost OH PLIF measurements at pressurized conditions.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Tagashira, Y. Harada, K. Nakamura, H. Miki, M. Matsukawa, D. Koyama
Optical image stabilization (OIS) systems maintain the three-dimensional focal position of a lens through mechanical actuation systems. This paper examines an optical lens for OIS that utilizes ultrasound vibration to alter the focal position, not only in the depth direction but also in the radial direction. The lens has a simple structure with no mechanical moving parts and consists of an ultrasound transducer divided into four pieces, a glass disk, and a transparent viscoelastic gel film that functions as a lens. The acoustic radiation force generated by the resonant flexural vibration of the glass disk can alter the surface profile of the gel film, allowing for a variable-focus function. The concave and convex lenses can be interchanged using two resonant vibration modes: the standing-wave mode, in which the vibration loop appears at the center, and the traveling-wave mode, in which the vibration node appears at the center. The positions of ultrasound vibrations on the lens can be controlled in a two-dimensional plane by adjusting the driving amplitudes of each channel, thereby achieving focus control in the radial direction. The focusing characteristics of the lens are evaluated through ray-tracing simulation.
{"title":"Focus control of a concave–convex ultrasonic gel lens in the radial direction","authors":"K. Tagashira, Y. Harada, K. Nakamura, H. Miki, M. Matsukawa, D. Koyama","doi":"10.1063/5.0218754","DOIUrl":"https://doi.org/10.1063/5.0218754","url":null,"abstract":"Optical image stabilization (OIS) systems maintain the three-dimensional focal position of a lens through mechanical actuation systems. This paper examines an optical lens for OIS that utilizes ultrasound vibration to alter the focal position, not only in the depth direction but also in the radial direction. The lens has a simple structure with no mechanical moving parts and consists of an ultrasound transducer divided into four pieces, a glass disk, and a transparent viscoelastic gel film that functions as a lens. The acoustic radiation force generated by the resonant flexural vibration of the glass disk can alter the surface profile of the gel film, allowing for a variable-focus function. The concave and convex lenses can be interchanged using two resonant vibration modes: the standing-wave mode, in which the vibration loop appears at the center, and the traveling-wave mode, in which the vibration node appears at the center. The positions of ultrasound vibrations on the lens can be controlled in a two-dimensional plane by adjusting the driving amplitudes of each channel, thereby achieving focus control in the radial direction. The focusing characteristics of the lens are evaluated through ray-tracing simulation.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yen Thi Nguyen, Chukwudubem Okafor, Puhan Zhao, Oishik Sen, Catalin R. Picu, Tommy Sewell, H. S. Udaykumar
Meso-scale calculations of energy localization and initiation in energetic material microstructures must capture the deformation and collapse of pores and high-temperature shear bands, which lead to hotspots. Because chemical reaction rates depend sensitively on temperature, predictive continuum models need to get the pore-collapse dynamics and resulting hotspot temperatures right; this imposes stringent demands on the fidelity of thermophysical model forms and parameters and on the numerical methods employed to perform high-resolution meso-scale calculations. Here, continuum material models for β-HMX are examined in the context of shock-induced pore collapse, treating predictions from all-atom molecular dynamics (MD) simulations as ground truth. Using atomistics-consistent material properties, we show that the currently available strength models for HMX fail to correctly capture pore collapse and hotspot temperatures. Insights from MD are then employed to advance a Modified Johnson–Cook (M-JC) strength model, which is shown to capture key aspects of the physics of shock-induced localization in HMX. The study culminates in a MD-guided strength model for β-HMX that produces continuum pore-collapse results in better alignment on several aspects with those predicted by MD, including pore-collapse mechanism and rate, shear-band formation in the collapse zone, and temperature, strain, and stress fields in the hotspot zone and the surrounding material. The resulting MD-informed/MD-determined M-JC model should improve the fidelity of meso-scale simulations to predict the detonation initiation of HMX-based energetic materials in microstructure-aware multi-scale frameworks.
{"title":"Continuum models for meso-scale simulations of HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) guided by molecular dynamics: Pore collapse, shear bands, and hotspot temperature","authors":"Yen Thi Nguyen, Chukwudubem Okafor, Puhan Zhao, Oishik Sen, Catalin R. Picu, Tommy Sewell, H. S. Udaykumar","doi":"10.1063/5.0232413","DOIUrl":"https://doi.org/10.1063/5.0232413","url":null,"abstract":"Meso-scale calculations of energy localization and initiation in energetic material microstructures must capture the deformation and collapse of pores and high-temperature shear bands, which lead to hotspots. Because chemical reaction rates depend sensitively on temperature, predictive continuum models need to get the pore-collapse dynamics and resulting hotspot temperatures right; this imposes stringent demands on the fidelity of thermophysical model forms and parameters and on the numerical methods employed to perform high-resolution meso-scale calculations. Here, continuum material models for β-HMX are examined in the context of shock-induced pore collapse, treating predictions from all-atom molecular dynamics (MD) simulations as ground truth. Using atomistics-consistent material properties, we show that the currently available strength models for HMX fail to correctly capture pore collapse and hotspot temperatures. Insights from MD are then employed to advance a Modified Johnson–Cook (M-JC) strength model, which is shown to capture key aspects of the physics of shock-induced localization in HMX. The study culminates in a MD-guided strength model for β-HMX that produces continuum pore-collapse results in better alignment on several aspects with those predicted by MD, including pore-collapse mechanism and rate, shear-band formation in the collapse zone, and temperature, strain, and stress fields in the hotspot zone and the surrounding material. The resulting MD-informed/MD-determined M-JC model should improve the fidelity of meso-scale simulations to predict the detonation initiation of HMX-based energetic materials in microstructure-aware multi-scale frameworks.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nikolay Britun, Michael K. T. Mo, Shih-Nan Hsiao, Fatima J. T. Arellano, Makoto Sekine, Masaru Hori
Number density of plasma-generated atoms or molecules is an important parameter for both fundamental research and applications. It can be measured in a straightforward manner, using vacuum-ultraviolet absorption spectroscopy, which is mainly possible in laboratory conditions as it may require bulky equipment, such as lasers. By contrast, optical actinometry is an alternative approach that only uses spontaneous emission from the plasma. This technique relies on the so-called corona excitation and uses emission line ratios between the gases with unknown and known concentrations (called actinometer in the last case). As a result of using line ratios, the additional density calibration is not required if the excitation cross sections are known. This study discusses Ar-based actinometry in low-pressure (roughly <1 kPa) plasma discharges with an emphasis on multiple line ratios. The work is particularly focused on the method’s applicability, the choice of Ar cross sections, and potential error sources. The influence of the additional excitation mechanisms is analyzed based on both experiments and modeling. The optical transitions for F, O, H, N, and P atoms along with expressions for their number density are presented, not requiring high optical resolution for measurements. For the sake of method validation, it is shown that in low-pressure radiofrequency discharges, a nearly excellent agreement between the actinometry data and the calibrated measurements can be achieved by careful selection of optical transitions.
等离子体产生的原子或分子的数量密度是基础研究和应用的重要参数。它可以用真空紫外吸收光谱法进行直接测量，但由于可能需要激光等笨重的设备，这种方法主要只能在实验室条件下使用。相比之下，光学锕系元素测量法是一种只利用等离子体自发辐射的替代方法。这种技术依赖于所谓的电晕激发，并使用未知浓度气体和已知浓度气体之间的发射线比率（在最后一种情况下称为放线仪）。由于使用了线比，如果已知激发截面，就不需要额外的密度校准。本研究讨论了低压（大约 1 kPa）等离子体放电中基于氩的放电测量法，重点是多线比。这项工作尤其关注该方法的适用性、氩截面的选择以及潜在的误差源。根据实验和建模分析了附加激发机制的影响。在不要求高光学分辨率测量的情况下，介绍了 F、O、H、N 和 P 原子的光学跃迁及其数量密度表达式。为了验证方法，研究表明在低压射频放电中，通过仔细选择光学跃迁，可以实现放电测量数据与校准测量数据之间近乎完美的一致性。
{"title":"Optical actinometry for number density measurements in low-pressure plasmas: Advantages, error sources, and method validation","authors":"Nikolay Britun, Michael K. T. Mo, Shih-Nan Hsiao, Fatima J. T. Arellano, Makoto Sekine, Masaru Hori","doi":"10.1063/5.0227576","DOIUrl":"https://doi.org/10.1063/5.0227576","url":null,"abstract":"Number density of plasma-generated atoms or molecules is an important parameter for both fundamental research and applications. It can be measured in a straightforward manner, using vacuum-ultraviolet absorption spectroscopy, which is mainly possible in laboratory conditions as it may require bulky equipment, such as lasers. By contrast, optical actinometry is an alternative approach that only uses spontaneous emission from the plasma. This technique relies on the so-called corona excitation and uses emission line ratios between the gases with unknown and known concentrations (called actinometer in the last case). As a result of using line ratios, the additional density calibration is not required if the excitation cross sections are known. This study discusses Ar-based actinometry in low-pressure (roughly &lt;1 kPa) plasma discharges with an emphasis on multiple line ratios. The work is particularly focused on the method’s applicability, the choice of Ar cross sections, and potential error sources. The influence of the additional excitation mechanisms is analyzed based on both experiments and modeling. The optical transitions for F, O, H, N, and P atoms along with expressions for their number density are presented, not requiring high optical resolution for measurements. For the sake of method validation, it is shown that in low-pressure radiofrequency discharges, a nearly excellent agreement between the actinometry data and the calibrated measurements can be achieved by careful selection of optical transitions.","PeriodicalId":15088,"journal":{"name":"Journal of Applied Physics","volume":null,"pages":null},"PeriodicalIF":3.2,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：