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933 results on '"Park, H-S."'

1. X-ray imaging and electron temperature evolution in laser-driven magnetic reconnection experiments at the National Ignition Facility

Author

Valenzuela-Villaseca, V., Molina, J. M., Schaeffer, D. B., Malko, S., Griff-McMahon, J., Lezhnin, K., Rosenberg, M. J., Hu, S. X., Kalantar, D., Trosseille, C., Park, H. -S., Remington, B. A., Fiksel, G., Uzdensky, D., Bhattacharjee, A., and Fox, W.

Subjects
Physics - Plasma Physics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Solar and Stellar Astrophysics
Abstract

We present results from X-ray imaging of high-aspect-ratio magnetic reconnection experiments driven at the National Ignition Facility. Two parallel, self-magnetized, elongated laser-driven plumes are produced by tiling 40 laser beams. A magnetic reconnection layer is formed by the collision of the plumes. A gated X-ray framing pinhole camera with micro-channel plate (MCP) detector produces multiple images through various filters of the formation and evolution of both the plumes and current sheet. As the diagnostic integrates plasma self-emission along the line of sight, 2-dimensional electron temperature maps $\langle T_e \rangle_Y$ are constructed by taking the ratio of intensity of these images obtained with different filters. The plumes have a characteristic temperature $\langle T_e \rangle_Y = 240 \pm 20$ eV at 2 ns after the initial laser irradiation and exhibit a slow cooling up to 4 ns. The reconnection layer forms at 3 ns with a temperature $\langle T_e \rangle_Y = 280 \pm 50$ eV as the result of the collision of the plumes. The error bars of the plumes and current sheet temperatures separate at $4$ ns, showing the heating of the current sheet from colder inflows. Using a semi-analytical model, we find that the observed heating of the current sheet is consistent with being produced by electron-ion drag, rather than the conversion of magnetic to kinetic energy., Comment: Submitted to Physics of Plasmas. 19 pages (total), 14 figures, 2 tables

Published
2024
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2. Nonproportionality of NaI(Tl) Scintillation Detector for Dark Matter Search Experiments

Author

Lee, S. M., Adhikari, G., Carlin, N., Cho, J. Y., Choi, J. J., Choi, S., Ezeribe, A. C., a, L. E. Fran., Ha, C., Hahn, I. S., Hollick, S. J., Jeon, E. J., Joo, H. W., Kang, W. G., Kauer, M., Kim, B. H., Kim, H. J., Kim, J., Kim, K. W., Kim, S. H., Kim, S. K., Kim, S. W., Kim, W. K., Kim, Y. D., Kim, Y. H., Ko, Y. J., Lee, D. H., Lee, E. K., Lee, H., Lee, H. S., Lee, H. Y., Lee, I. S., Lee, J., Lee, J. Y., Lee, M. H., Lee, S. H., Lee, Y. J., Leonard, D. S., Luan, N. T., Manzato, B. B., Maruyama, R. H., Neal, R. J., Nikkel, J. A., Olsen, S. L., Park, B. J., Park, H. K., Park, H. S., Park, J. C., Park, K. S., Park, S. D., Pitta, R. L. C., Prihtiadi, H., Ra, S. J., Rott, C., Shin, K. A., Cavalcante, D. F. F. S., Scarff, A., Son, M. K., Spooner, N. J. C., Truc, L. T., Yang, L., and Yu, G. H.

Subjects
High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract

We present a comprehensive study of the nonproportionality of NaI(Tl) scintillation detectors within the context of dark matter search experiments. Our investigation, which integrates COSINE-100 data with supplementary $\gamma$ spectroscopy, measures light yields across diverse energy levels from full-energy $\gamma$ peaks produced by the decays of various isotopes. These $\gamma$ peaks of interest were produced by decays supported by both long and short-lived isotopes. Analyzing peaks from decays supported only by short-lived isotopes presented a unique challenge due to their limited statistics and overlapping energies, which was overcome by long-term data collection and a time-dependent analysis. A key achievement is the direct measurement of the 0.87 keV light yield, resulting from the cascade following electron capture decay of $^{22}$Na from internal contamination. This measurement, previously accessible only indirectly, deepens our understanding of NaI(Tl) scintillator behavior in the region of interest for dark matter searches. This study holds substantial implications for background modeling and the interpretation of dark matter signals in NaI(Tl) experiments., Comment: 12 pages, 7 figures

Published
2024
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3. Alpha backgrounds in NaI(Tl) crystals of COSINE-100

Author

Adhikari, G., Carlin, N., Cavalcante, D. F. F. S., Cho, J. Y., Choi, J. J., Choi, S., Ezeribe, A. C., Franca, L. E., Ha, C., Hahn, I. S., Hollick, S. J., Jeon, E. J., Joo, H. W., Kang, W. G., Kauer, M., Kim, B. H., Kim, H. J., Kim, J., Kim, K. W., Kim, S. H., Kim, S. K., Kim, S. W., Kim, W. K., Kim, Y. D., Kim, Y. H., Ko, Y. J., Lee, D. H., Lee, E. K., Lee, H., Lee, H. S., Lee, H. Y., Lee, I. S., Lee, J., Lee, J. Y., Lee, M. H., Lee, S. H., Lee, S. M., Lee, Y. J., Leonard, D. S., Luan, N. T., Manzato, B. B., Maruyama, R. H., Neal, R. J., Nikkel, J. A., Olsen, S. L., Park, B. J., Park, H. K., Park, H. S., Park, J. C., Park, K. S., Park, S. D., Pitta, R. L. C., Prihtiadi, H., Ra, S. J., Rott, C., Scar, A., Shin, K. A., Son, M. K., Spooner, N. J. C., Truc, L. T., Yang, L., Yu, G. H., and COSINE-100, for

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract

COSINE-100 is a dark matter direct detection experiment with 106 kg NaI(Tl) as the target material. 210Pb and daughter isotopes are a dominant background in the WIMP region of interest and are detected via beta decay and alpha decay. Analysis of the alpha channel complements the background model as observed in the beta/gamma channel. We present the measurement of the quenching factors and Monte Carlo simulation results and activity quantification of the alpha decay components of the COSINE-100 NaI(Tl) crystals. The data strongly indicate that the alpha decays probabilistically undergo two possible quenching factors but require further investigation. The fitted results are consistent with independent measurements and improve the overall understanding of the COSINE-100 backgrounds. Furthermore, the half-life of 216Po has been measured to be 143.4 +/- 1.2 ms, which is consistent with and more precise than recent measurements.

Published
2023
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5. Insensitivity of a turbulent laser-plasma dynamo to initial conditions

Author

Bott, A. F. A., Chen, L., Tzeferacos, P., Palmer, C. A. J., Bell, A. R., Bingham, R., Birkel, A., Froula, D. H., Katz, J., Kunz, M. W., Li, C. -K., Park, H-S., Petrasso, R., Ross, J. S., Reville, B., Ryu, D., Séguin, F. H., White, T. G., Schekochihin, A. A., Lamb, D. Q., and Gregori, G.

Subjects
Physics - Plasma Physics, Astrophysics - High Energy Astrophysical Phenomena
Abstract

It has recently been demonstrated experimentally that a turbulent plasma created by the collision of two inhomogeneous, asymmetric, weakly magnetised laser-produced plasma jets can generate strong stochastic magnetic fields via the small-scale turbulent dynamo mechanism, provided the magnetic Reynolds number of the plasma is sufficiently large. In this paper, we compare such a plasma with one arising from two pre-magnetised plasma jets whose creation is identical save for the addition of a strong external magnetic field imposed by a pulsed magnetic field generator (`MIFEDS'). We investigate the differences between the two turbulent systems using a Thomson-scattering diagnostic, X-ray self-emission imaging and proton radiography. The Thomson-scattering spectra and X-ray images suggest that the presence of the external magnetic field has a limited effect on the plasma dynamics in the experiment. While the presence of the external magnetic field induces collimation of the flows in the colliding plasma jets and the initial strengths of the magnetic fields arising from the interaction between the colliding jets are significantly larger as a result of the external field, the energy and morphology of the stochastic magnetic fields post-amplification are indistinguishable. We conclude that, for turbulent laser-plasmas with super-critical magnetic Reynolds numbers, the dynamo-amplified magnetic fields are determined by the turbulent dynamics rather than the seed fields and modest changes in the initial flow dynamics of the plasma, a finding consistent with theoretical expectations and simulations of turbulent dynamos., Comment: 13 pages, 12 figures

Published
2022
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6. Decadal stability in coral cover could mask hidden changes on reefs in the East Asian Seas

Author

Chan, Y. K. S., Affendi, Y. A., Ang, P. O., Baria-Rodriguez, M. V., Chen, C. A., Chui, A. P. Y., Giyanto, Glue, M., Huang, H., Kuo, C-Y., Kim, S. W., Lam, V. Y. Y., Lane, D. J. W., Lian, J. S., Lin, S. M. N. N., Lunn, Z., Nañola, Jr, C. L., Nguyen, V. L., Park, H. S., Suharsono, Sutthacheep, M., Vo, S. T., Vibol, O., Waheed, Z., Yamano, H., Yeemin, T., Yong, E., Kimura, T., Tun, K., Chou, L. M., and Huang, D.

Published
2023
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10. Explosive fragmentation of additively manufactured stainless steel.

Author

Callahan, M., Sun, D., Linne, M. A., Wu, A. S., Campbell, G. H., Friedman, B., Rodriguez, J., Burke, S., Lodes, A., Hansen, K., Mickelson, K., Wraith, R., Nicolino, J. J., and Park, H.-S.

Subjects
STAINLESS steel, STEEL manufacture, DOPPLER velocimetry, STRAINS & stresses (Mechanics), STRESS concentration
Abstract

Properties of fragmentation from an explosively driven 316L stainless steel spherical shell section fabricated by a laser powder bed additive manufacturing process with minimal surface finishing are investigated. This shell is driven by an insensitive high explosive, resulting in high strain rate deformation (>8 × 103 s−1) and failure of the stainless steel. Photonic Doppler velocimetry measures the expansion rate; dynamic radiography and high-speed imaging capture the fracture behavior of the stainless steel. The fracture response of the additively manufactured stainless steel shell is compared to published experimental results on additively manufactured 316L stainless steel and conventionally manufactured wrought 316L and 304 stainless steel shell fragmentation. Despite preferred crack orientation, suggesting the influence of surface grooves on fracture time, fragment size is identical to that measured in a similar experiment on wrought 304 stainless steel. Further analysis indicates that the 316L additively manufactured stainless steel shell exhibits comparable spall strength and fragmentation toughness to conventionally manufactured stainless steel yet lower failure strain due to surface stress concentrations. [ABSTRACT FROM AUTHOR]

Published
2023
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11. Alpha backgrounds in the AMoRE-Pilot experiment

Author

Alenkov, V., Bae, H. W., Beyer, J., Boiko, R. S., Boonin, K., Buzanov, O., Chanthima, N., Cheoun, M. K., Choi, S. H., Danevich, F. A., Djamal, M., Drung, D., Enss, C., Fleischmann, A., Gangapshev, A., Gastaldo, L., Gavriljuk, Yu. M., Gezhaev, A., Grigoryeva, V. D., Gurentsov, V., Ha, D. H., Ha, C., Ha, E. J., Hahn, I., Jeon, E. J., Jeon, J., Jo, H. S., Kaewkhao, J., Kang, C. S., Kang, S. J., Kang, W. G., Karki, S., Kazalov, V., Khan, A., Khan, S., Kim, D.-Y., Kim, G. W., Kim, H. B., Kim, H. J., Kim, H. L., Kim, H. S., Kim, I., Kim, W. T., Kim, S. R., Kim, S. C., Kim, S. K., Kim, Y. D., Kim, Y. H., Kirdsiri, K., Ko, Y. J., Kobychev, V. V., Kornoukhov, V., Kuz’minov, V., Kwon, D. H., Lee, C., Lee, E. K., Lee, H. J., Lee, H. S., Lee, J., Lee, J. S., Lee, J. Y., Lee, K. B., Lee, M. H., Lee, M. K., Lee, S. H., Lee, S. W., Lee, S. W., Leonard, D. S., Li, J., Li, Y., Limkitjaroenporn, P., Mailyan, B., Makarov, E. P., Oh, S. Y., Oh, Y. M., Gileva, O., Olsen, S., Pabitra, A., Panasenko, S., Pandey, I., Park, C. W., Park, H. K., Park, H. S., Park, K. S., Park, S. Y., Polischuk, O. G., Prihtiadi, H., Ra, S. J., Ratkevich, S., Rooh, G., Sari, M. B., Seo, J., Seo, K. M., Shin, J. W., Shin, K. A., Shlegel, V. N., Siyeon, K., Sokur, N. V., Son, J.-K., Srisittipokakun, N., Toibaev, N., Tretyak, V. I., Wirawan, R., Woo, K. R., Yoon, Y. S., and Yue, Q.

Published
2022
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12. A deep learning approach to fast analysis of collective Thomson scattering spectra.

Author

Pokornik, M., Higginson, D. P., Swadling, G., Larson, D., Moczulski, K., Pollock, B., Tubman, E., Tzeferacos, P., Park, H. S., Beg, F., Arefiev, A., and Manuel, M.

Abstract

Fast analysis of collective Thomson scattering ion acoustic wave features using a deep convolutional neural network model is presented. The network was trained from spectra to predict the plasma parameters, including ion velocities, population fractions, and ion and electron temperatures. A fully kinetic particle-in-cell simulation was used to model a laboratory astrophysics experiment and simulate a diagnostic image of the ion acoustic wave feature. Network predictions were compared with Bayesian inference of the plasma model parameters for both the simulated and experimentally measured images. Both approaches were fairly accurate predicting the simulated image and the network predictions matched a good portion of the Bayesian results for the experimentally measured image. The Bayesian approach is more robust to noise and motivates future work to train deep learning models with realistic noise. The advantage of the deep learning model is making thousands of predictions in a few hundred milliseconds, compared to a few seconds to minutes per prediction for the optimization and Bayesian approaches presented here. The results demonstrate promising capabilities of deep learning models to analyze Thomson data orders of magnitude faster than conventional methods when using the neural network for standalone analysis. If more rigorous analysis is needed, neural network predictions can be used to quickly initialize other optimization methods and increase chances of success. This is especially useful when the dataset becomes very large or highly dimensional and manually refining initial conditions for the entire dataset are no longer tractable. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Identification of new isomers in 228Ac: impact on dark matter searches

Author

Kim, K. W., Adhikari, G., de Souza, E. Barbosa, Carlin, N., Choi, J. J., Choi, S., Djamal, M., Ezeribe, A. C., França, L. E., Ha, C., Hahn, I. S., Jeon, E. J., Jo, J. H., Kang, W. G., Kauer, M., Kim, H., Kim, H. J., Kim, S. H., Kim, S. K., Kim, W. K., Kim, Y. D., Kim, Y. H., Ko, Y. J., Lee, E. K., Lee, H., Lee, H. S., Lee, H. Y., Lee, I. S., Lee, J., Lee, J. Y., Lee, M. H., Lee, S. H., Lee, S. M., Leonard, D. S., Manzato, B. B., Maruyama, R. H., Neal, R. J., Olsen, S. L., Park, B. J., Park, H. K., Park, H. S., Park, K. S., Pitta, R. L. C., Prihtiadi, H., Ra, S. J., Rott, C., Shin, K. A., Scarff, A., Spooner, N. J. C., Thompson, W. G., Yang, L., and Yu, G. H.

Published
2021
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18. Nonplanar effects in simulations of laser-driven ejecta microjet experiments.

Author

Horwitz, J. A. K., Sun, Y., Pino, J., Morgan, B. E., Mackay, K. K., Najjar, F. M., Ali, S. J., Eggert, J. H., Ping, Y., Park, H.-S., and Saunders, A. M.

Subjects
LASER pulses, SPATIAL variation, TRAFFIC safety, VERY light jets, THREE-dimensional modeling, RADIOGRAPHS
Abstract

Recent experiments of laser-driven ejecta microjets performed at OMEGA 60 reveal tortuous jets whereby the jets appear to deviate from their initial trajectory as they travel in vacuum. To understand these data, we perform two dimensional numerical simulations, considering different target thicknesses, pressures, and models of the drive conditions. In particular, modeling the finite laser spot size appears essential in reproducing qualitatively the non-planar shock observed in the experiment. Simulations capture jet deflection by accounting for a slight misalignment of the laser pointing with respect to the groove axis along with spatial variation of the laser pulse intensity. The principal physical mechanism appears to be that lateral momentum is imparted by release waves arising from the non-planar drive. The induced off-axis velocity is small in comparison to the jet axial velocity but integrates into a pronounced deflection over the course of the experiment. The analysis of jet axial and lateral mass distributions is found to be reproduced reasonably by the simulations. Simulated radiographs are in qualitative agreement with the experiments, though their differences point to potential shortcomings in modeling strictly three-dimensional experiments using two-dimensional hydrodynamic simulations. The simple analysis is able to explain part of the observed discrepancy in simulated vs experimental jet masses. [ABSTRACT FROM AUTHOR]

Published
2024
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22. A direct-drive exploding-pusher implosion as the first step in development of a monoenergetic charged-particle backlighting platform at the National Ignition Facility

Author

Rosenberg, M.J., Zylstra, A.B., Séguin, F.H., Rinderknecht, H.G., Frenje, J.A., Gatu Johnson, M., Sio, H., Waugh, C.J., Sinenian, N., Li, C.K., Petrasso, R.D., LePape, S., Ma, T., Mackinnon, A.J., Rygg, J.R., Amendt, P.A., Bellei, C., Benedetti, L.R., Berzak Hopkins, L., Bionta, R.M., Casey, D.T., Divol, L., Edwards, M.J., Glenn, S., Glenzer, S.H., Hicks, D.G., Kimbrough, J.R., Landen, O.L., Lindl, J.D., MacPhee, A., McNaney, J.M., Meezan, N.B., Moody, J.D., Moran, M.J., Park, H.-S., Pino, J., Remington, B.A., Robey, H., Rosen, M.D., Wilks, S.C., Zacharias, R.A., McKenty, P.W., Hohenberger, M., Radha, P.B., Edgell, D., Marshall, F.J., Delettrez, J.A., Glebov, V.Yu., Betti, R., Goncharov, V.N., Knauer, J.P., Sangster, T.C., Herrmann, H.W., Hoffman, N.M., Kyrala, G.A., Leeper, R.J., Olson, R.E., Kilkenny, J.D., and Nikroo, A.

Published
2016
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24. Enhanced converse flexoelectricity in piezoelectric composites by coupling topology optimization with homogenization.

Author

Chen, X., Yvonnet, J., Park, H. S., and Yao, S.

Subjects
PIEZOELECTRIC composites, FLEXOELECTRICITY, ELECTROMECHANICAL effects, ELECTRIC fields, TOPOLOGY, ASYMPTOTIC homogenization
Abstract

We demonstrate that large apparent converse flexoelectric properties can be obtained in piezoelectric composites using theoretical approaches. To do so, we first present a numerical homogenization method accounting for all electromechanical terms related to strain and the electric field gradient. We then evaluate the coefficients of the model by numerical simulations on periodic piezoelectric composites. After combining the homogenization approach with topology optimization to enhance the converse properties of the composite, we present numerical results that reveal that the apparent converse flexoelectric coefficients, as well as those associated with the higher order coupling terms involving the electric field gradient, are of the same order as the direct flexoelectric properties of the local constituents. These results suggest that both converse and higher order electromechanical coupling effects may contribute strongly to the flexoelectric response and properties of piezoelectric composites. Finally, we show that it is theoretically possible to obtain optimized designs of composites with apparent converse flexoelectric properties 1–2 orders of magnitude larger than ones obtained with naïve guess designs. [ABSTRACT FROM AUTHOR]

Published
2021
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25. First results from the AMoRE-Pilot neutrinoless double beta decay experiment

Author

Alenkov, V., Bae, H. W., Beyer, J., Boiko, R. S., Boonin, K., Buzanov, O., Chanthima, N., Cheoun, M. K., Chernyak, D. M., Choe, J. S., Choi, S., Danevich, F. A., Djamal, M., Drung, D., Enss, C., Fleischmann, A., Gangapshev, A. M., Gastaldo, L., Gavriljuk, Yu. M., Gezhaev, A. M., Grigoryeva, V. D., Gurentsov, V. I., Gylova, O., Ha, C., Ha, D. H., Ha, E. J., Hahn, I. S., Jang, C. H., Jeon, E. J., Jeon, J. A., Jo, H. S., Kaewkhao, J., Kang, C. S., Kang, S. J., Kang, W. G., Kazalov, V. V., Kempf, S., Khan, A., Khan, S., Kim, D. Y., Kim, G. W., Kim, H. B., Kim, H. J., Kim, H. L., Kim, H. S., Kim , I., Kim, S. C., Kim, S. G., Kim, S. K., Kim, S. R., Kim, W. T., Kim, Y. D., Kim, Y. H., Kirdsiri, K., Ko, Y. J., Kobychev, V. V., Kornoukhov, V., Kuzminov, V. V., Kwon, D. H., Lee, C., Lee, E. K., Lee, H. J., Lee, H. S., Lee, J. S., Lee, J. Y., Lee, K. B., Lee, M. H., Lee, M. K., Lee, S. W., Lee, S. W., Lee, S. H., Leonard, D., Li, J., Li, J., Li, Y., Limkitjaroenporn, P., Makarov, E. P., Oh, S. Y., Oh, Y. M., Olsen, S. L., Pabitra, A., Panasenko, S. I., Pandey, I., Park, C. W., Park, H. K., Park, H. S., Park, K. S., Park, S. Y., Poda, D. V., Polischuk, O. G., Prihtiadi, H., Ra, S. J., Ratkevich, S. S., Rooh, G., Sari, M. B., Seo, K. M., Shin, J. W., Shin, K. A., Shlegel, V. N., Siyeon, K., So, J. H., Son, J. K., Srisittipokakun, N., Sujita, K., Tretyak, V. I., Wirawan, R., Woo, K. R., Yoon, Y. S., Yue, Q., and Zaman, S. U.

Published
2019
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26. Limits on interactions between weakly interacting massive particles and nucleons obtained with NaI(Tl) crystal detectors

Author

The KIMS collaboration, Kim, K. W., Adhikari, G., Adhikari, P., Choi, S., Ha, C., Hahn, I. S., Jeon, E. J., Joo, H. W., Kang, W. G., Kim, H. J., Kim, N. Y., Kim, S. K., Kim, Y. D., Kim, Y. H., Ko, Y. J., Lee, H. S., Lee, J. S., Lee, J. Y., Lee, M. H., Leonard, D. S., Olsen, S. L., Park, B. J., Park, H. K., Park, H. S., and Park, K. S.

Published
2019
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28. In situ X-ray diffraction measurement of shock-wave-driven twinning and lattice dynamics

Author

Wehrenberg, C. E., McGonegle, D., Bolme, C., Higginbotham, A., Lazicki, A., Lee, H. J., Nagler, B., Park, H.-S., Remington, B. A., Rudd, R. E., Sliwa, M., Suggit, M., Swift, D., Tavella, F., Zepeda-Ruiz, L., and Wark, J. S.

Subjects
Shock waves -- Observations, Twinning (Crystallography) -- Measurement -- Observations, X-ray diffraction -- Measurement -- Usage, Environmental issues, Science and technology, Zoology and wildlife conservation
Abstract

Author(s): C. E. Wehrenberg (corresponding author) [1]; D. McGonegle [2]; C. Bolme [3]; A. Higginbotham [4]; A. Lazicki [1]; H. J. Lee [5]; B. Nagler [5]; H.-S. Park [1]; B. [...]

Published
2017
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32. Hydrodynamic computations of high-power laser drives generating metal ejecta jets from surface grooves.

Author

Mackay, K. K., Najjar, F. M., Ali, S. J., Eggert, J. H., Haxhimali, T., Morgan, B. E., Park, H. S., Ping, Y., Rinderknecht, H. G., Stan, C. V., and Saunders, A. M.

Subjects
APPLIED sciences, PHASE transitions, EQUATIONS of state, HIGH power lasers, FREE surfaces, URANIUM, STRENGTH of materials, TIN alloys
Abstract

Understanding dynamic fragmentation in shock-loaded metals and predicting properties of the resulting ejecta are of considerable importance for both basic and applied science. The nature of material ejection has been shown to change drastically when the free surface melts on compression or release. In this work, we present hydrodynamic simulations of laser-driven microjetting from micron-scale grooves on a tin surface. We study microjet formation across a range of shock strengths from drives that leave the target solid after release to drives that induce shock melting in the target. The shock-state particle velocity (U p) varies from 0.3 to 3 km/s and the shock breakout pressure is 3–120 GPa. The microjet tip velocity is 1–8 km/s and the free-surface velocity varies from 0.1 to 5 km/s. Two tin equations of state are examined: a "soft" model (LEOS 501) where the target melts for U p > --> 1 km/s and a more detailed multiphase model (SESAME 2161) that melts for U p > --> 1.4 km/s. We use these two models to examine the influence of phase change and the choice of the material model on microjet formation and evolution. We observe in our computational results that jet formation can be classified into three regimes: a low-energy regime where material strength affects jet formation, a moderate-energy regime dominated by the changing phase of tin material, and a high-energy regime where results are insensitive to the material model and jet formation is described by an idealized steady-jet theory. Using an ensemble of 2D simulations, we show that these trends hold across a wide range of drive energies and groove angles. [ABSTRACT FROM AUTHOR]

Published
2020
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33. Topologically switchable behavior induced by an elastic instability in a phononic waveguide.

Author

Nguyen, B. H., Zhuang, X., Park, H. S., and Rabczuk, T.

Subjects
UNIT cell, PHONONIC crystals, TOPOLOGICAL insulators, GEOMETRIC shapes, QUANTUM spin Hall effect, PHASE transitions
Abstract

While topological insulators have been widely studied, they typically appear in configurations and properties that are set once a structure is fabricated. As such, there is significant interest in developing topologically tunable or switchable concepts. In this work, we demonstrate that geometric nonlinearity in the form of an elastic snap-through instability can be exploited to switch the topological properties of a Timoshenko arch beam unit cell. We first demonstrate that the phonon band structure can be tuned using geometric nonlinearity and large displacement to reveal the existence of a topological phase transition point. To make this concept fully stable under the removal of the applied force, we then demonstrate the emergence of a bistable unit cell by varying the parameters of the unit cell. In doing so, we show that the bistability of the arch beam unit cell can be harnessed to design a switch that controls the topological nature of an interface between two different 1D phononic crystals. [ABSTRACT FROM AUTHOR]

Published
2020
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34. Background model for the NaI(Tl) crystals in COSINE-100

Author

Adhikari, P., Adhikari, G., Souza, E. Barbosa de, Carlin, N., Choi, S., Choi, W. Q., Djamal, M., Ezeribe, A. C., Ha, C., Hahn, I. S., Hubbard, A. J. F., Jeon, E. J., Jo, J. H., Joo, H. W., Kang, W. G., Kauer, M., Kang, W. S., Kim, B. H., Kim, H., Kim, H. J., Kim, K. W., Kim, M. C., Kim, N. Y., Kim, S. K., Kim, Y. D., Kim, Y. H., Kudryavtsev, V. A., Lee, H. S., Lee, J., Lee, J. Y., Lee, M. H., Leonard, D. S., Lynch, W. A., Maruyama, R. H., Mouton, F., Olsen, S. L., Park, H. K., Park, H. S., Park, J. S., Park, K. S., Pettus, W., Prihtiadi, H., Ra, S., Rott, C., Scarff, A., Spooner, N. J. C., Thompson, W. G., Yang, L., and Yong, S. H.

Published
2018
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35. Initial performance of the COSINE-100 experiment

Author

Adhikari, G., Adhikari, P., de Souza, E. Barbosa, Carlin, N., Choi, S., Choi, W. Q., Djamal, M., Ezeribe, A. C., Ha, C., Hahn, I. S., Hubbard, A. J. F., Jeon, E. J., Jo, J. H., Joo, H. W., Kang, W. G., Kang, W., Kauer, M., Kim, B. H., Kim, H., Kim, H. J., Kim, K. W., Kim, M. C., Kim, N. Y., Kim, S. K., Kim, Y. D., Kim, Y. H., Kudryavtsev, V. A., Lee, H. S., Lee, J., Lee, J. Y., Lee, M. H., Leonard, D. S., Lim, K. E., Lynch, W. A., Maruyama, R. H., Mouton, F., Olsen, S. L., Park, H. K., Park, H. S., Park, J. S., Park, K. S., Pettus, W., Pierpoint, Z. P., Prihtiadi, H., Ra, S., Rogers, F. R., Rott, C., Scarff, A., Spooner, N. J. C., Thompson, W. G., Yang, L., and Yong, S. H.

Published
2018
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42. Simulation of laser-driven, ablated plasma flows in collisionless shock experiments on OMEGA and the NIF

Author

Grosskopf, M.J., Drake, R.P., Kuranz, C.C., Rutter, E.M., Ross, J.S., Kugland, N.L., Plechaty, C., Remington, B.A., Spitkovsky, A., Gargate, L., Gregori, G., Bell, A., Murphy, C.D., Meinecke, J., Reville, B., Sakawa, Y., Kuramitsu, Y., Takabe, H., Froula, D.H., Fiksel, G., Miniati, F., Koenig, M., Ravasio, A., Liang, E., Fu, W., Woolsey, N., and Park, H.-S.

Published
2013
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43. Modeling HEDLA magnetic field generation experiments on laser facilities

Author

Fatenejad, M., Bell, A.R., Benuzzi-Mounaix, A., Crowston, R., Drake, R.P., Flocke, N., Gregori, G., Koenig, M., Krauland, C., Lamb, D., Lee, D., Marques, J.R., Meinecke, J., Miniati, F., Murphy, C.D., Park, H.-S., Pelka, A., Ravasio, A., Remington, B., Reville, B., Scopatz, A., Tzeferacos, P., Weide, K., Woolsey, N., Young, R., and Yurchak, R.

Published
2013
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46. Comparison Of Mercury Distribution Between The Types Of Spent Fluorescent Lamp

Author

Rhee S.W., Park H.-S., and Choi H.H.

Subjects
spent fluorescent lamp, types, phosphor powder, mercury distribution, Mining engineering. Metallurgy, TN1-997, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

Spent fluorescent lamps(SFLs) such as linear type lamp, compact type lamp and U-type lamp are used to estimate mercury distribution in the components of lamps. Determination of mercury concentration in the components of spent fluorescent lamp is performed by the DMA method. Mercury concentration in the components of spent fluorescent lamp can be varied with the manufactures of lamp. Mercury portion in phosphor powder and glass from any types of spent fluorescent lamp is estimated to be higher than 99% by the analysis of mercury distribution. Through mercury distribution in the components for SFLs, the mercury concentration in phosphor powder is much higher than that in other components regardless of the type of lamp. Hence, it is desirable that phosphor powder of spent fluorescent lamps should be controlled separately and safely.

Published
2015
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