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332 results on '"Tam, S. W."'

1. Quantum key distribution over multicore fiber

Author

Dynes, J. F., Kindness, S. J., Tam, S. W. -B., Plews, A., Sharpe, A. W., Lucamarini, M., Fröhlich, B., Yuan, Z. L., Penty, R. V., and Shields, A. J.

Subjects
Quantum Physics
Abstract

We present the first quantum key distribution (QKD) experiment over multicore fiber. With space division multiplexing, we demonstrate that weak QKD signals can coexist with classical data signals launched at full power in a 53 km 7-core fiber, while showing negligible degradation in performance. Based on a characterization of intercore crosstalk, we perform additional simulations highlighting that classical data bandwidths beyond 1Tb/s can be supported with high speed QKD on the same fiber., Comment: 7 pages, 5 figures

Published
2016
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2. Precipitation of Auroral Electrons Accelerated at Very High Altitudes: Impact on the Ionosphere and a Possible Acceleration Mechanism.

Author

Imajo, S., Miyoshi, Y., Kazama, Y., Asamura, K., Shinohara, I., Shiokawa, K., Kasahara, Y., Kasaba, Y., Matsuoka, A., Wang, S.‐Y., Tam, S. W. Y., Chang, T.‐F., Wang, B.‐J., Jun, C.‐W., Teramoto, M., Kurita, S., Tsuchiya, F., Kumamoto, A., Saito, K., and Hori, T.

Subjects
ELECTRON distribution, AURORAS, ION beams, ELECTRIC fields, MAGNETOSPHERE
Abstract

The Arase satellite observed the precipitation of monoenergetic electrons accelerated from a very high altitude above 32,000 km altitude on 16 September 2017. The event was selected in the period when the high‐angular resolution channel of the electron detector looked at pitch angles within ∼5° from the ambient magnetic field direction, and thereby was the first to examine the detailed distribution of electron flux near the energy‐dependent loss cone at such high altitudes. The potential energy below the satellite estimated from the observed energy‐dependence of the loss cone was consistent with the energy of the upgoing ion beams, indicating that ionospheric ions were accelerated by a lower‐altitude acceleration region. The accelerated electrons inside the loss cone carried a significant net field‐aligned current (FAC) density corresponding to ionospheric‐altitude FAC of up to ∼3μA/m2. Based on the anisotropy of the accelerated electrons, we estimated the height of the upper boundary of the acceleration region to be >∼2 RE above the satellite. The height distribution of the acceleration region below the satellite, estimated from the frequency of auroral kilometric radiation, was ∼4,000–13,000 km altitude, suggesting that the very‐high‐altitude acceleration region was separated from the lower acceleration region. Additionally, we observed time domain structure (TDS) electric fields on a subsecond time scale with a thin FAC indicated by magnetic deflections. Such a TDS may be generated by the formation of double layers in the magnetotail, and its potential drop could significantly contribute (∼40%–60%) to the parallel energization of precipitating auroral electrons. Plain Language Summary: The auroral arc is produced by electrons in the magnetosphere accelerated downward by a quasi‐static electric field. The region of the electric field, so called the auroral acceleration region, is typically located just above the ionosphere, at altitudes of a few thousand kilometers. However, recent studies have shown that it can be extended to altitudes higher than 30,000 km. The mechanism and impact of such a very‐high‐altitude acceleration region remain a mystery. The high‐angular resolution electron detector on board the Arase satellite successfully measured current and energy flows carried by the electron accelerated at the very‐high‐altitude acceleration region above the satellite altitude of 32,000 km. This acceleration at very‐high‐altitudes contributed significantly to the energy flow into the ionosphere. Based on the anisotropy of the accelerated electrons, the frequency of auroral kilometric radiation, and the presence of spiky electrostatic waves, we estimate that the very‐high‐altitude acceleration region was located more than 12,000 km above the satellite as a thin charge separation layer, apart from the acceleration region below the satellite. Our results suggest that localized electric fields at very high altitudes, which were not previously associated with the aurora, can energize auroral electrons and affect auroral visibility. Key Points: We comprehensively analyzed a very‐high‐altitude (>32,000 km) auroral acceleration eventNet precipitation of accelerated electrons significantly contributes to the field‐aligned current and energy flux into the ionosphereDouble layers in the magnetotail are possible candidates for very‐high‐altitude auroral accelerations [ABSTRACT FROM AUTHOR]

Published
2024
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3. Understanding the Self-Heating Effects Measured With the AC Output Conductance Method in Advanced FinFET Nodes

Author

Tondelli, L., Asanovski, R., Scholten, A. J., Dinh, T. V., Tam, S.-W., Pijper, R. M. T., and Selmi, L.

Abstract

Accurate determination of thermal resistances having a clear physical interpretation is crucial for analyzing self-heating effects (SHEs) in bulk FinFETs and ensuring reliable circuit operation. In this article, we use extensive electrothermal simulations, calibrated against experiments, to validate a popular method to monitor SHEs based on the measured AC output conductance. The results confirm that nanoscale silicon fins exhibit degraded thermal conductivity compared with the bulk silicon case. Then, we explore the relationship between the temperature extracted by the output conductance method and the maximum temperature inside the fin (which is a useful parameter to study device reliability) as a function of device bias and dimensions, providing a few projections toward scaled technology nodes. Our results show that the following hold: 1) the overtemperature extracted with the AC output conductance method represents an average overtemperature across the device active area and 2) the AC conductance method largely underestimates the peak temperature of long-channel devices; less so for short-channel ones. In this latter case, however, the difference between the above temperatures changes appreciably as a function of gate voltage.

Published
2024
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4. Correspondence of Pi2 pulsations, aurora luminosity, and plasma flux fluctuation near a substorm brightening aurora: Arase observations

Author

Chen, L., primary, Shiokawa, K., additional, Miyoshi, Y., additional, Oyama, S., additional, Jun, C‐W., additional, Ogawa, Y., additional, Hosokawa, K., additional, Kazama, Y., additional, Wang, S. Y., additional, Tam, S. W. Y., additional, Chang, T. F., additional, Wang, B. J., additional, Asamura, K., additional, Kasahara, S., additional, Yokota, S., additional, Hori, T., additional, Keika, K., additional, Kasaba, Y., additional, Kumamoto, A., additional, Tsuchiya, F., additional, Shoji, M., additional, Kasahara, Y., additional, Matsuoka, A., additional, Shinohara, I., additional, and Nakamura, S., additional

Published
2023
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5. The Space Physics Environment Data Analysis System (SPEDAS)

Author

Angelopoulos, V., Cruce, P., Drozdov, A., Grimes, E. W., Hatzigeorgiu, N., King, D. A., Larson, D., Lewis, J. W., McTiernan, J. M., Roberts, D. A., Russell, C. L., Hori, T., Kasahara, Y., Kumamoto, A., Matsuoka, A., Miyashita, Y., Miyoshi, Y., Shinohara, I., Teramoto, M., Faden, J. B., Halford, A. J., McCarthy, M., Millan, R. M., Sample, J. G., Smith, D. M., Woodger, L. A., Masson, A., Narock, A. A., Asamura, K., Chang, T. F., Chiang, C.-Y., Kazama, Y., Keika, K., Matsuda, S., Segawa, T., Seki, K., Shoji, M., Tam, S. W. Y., Umemura, N., Wang, B.-J., Wang, S.-Y., Redmon, R., Rodriguez, J. V., Singer, H. J., Vandegriff, J., Abe, S., Nose, M., Shinbori, A., Tanaka, Y.-M., UeNo, S., Andersson, L., Dunn, P., Fowler, C., Halekas, J. S., Hara, T., Harada, Y., Lee, C. O., Lillis, R., Mitchell, D. L., Argall, M. R., Bromund, K., Burch, J. L., Cohen, I. J., Galloy, M., Giles, B., Jaynes, A. N., Le Contel, O., Oka, M., Phan, T. D., Walsh, B. M., Westlake, J., Wilder, F. D., Bale, S. D., Livi, R., Pulupa, M., Whittlesey, P., DeWolfe, A., Harter, B., Lucas, E., Auster, U., Bonnell, J. W., Cully, C. M., Donovan, E., Ergun, R. E., Frey, H. U., Jackel, B., Keiling, A., Korth, H., McFadden, J. P., Nishimura, Y., Plaschke, F., Robert, P., Turner, D. L., Weygand, J. M., Candey, R. M., Johnson, R. C., Kovalick, T., Liu, M. H., McGuire, R. E., Breneman, A., Kersten, K., and Schroeder, P.

Published
2019
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6. Observation of Source Plasma and Field Variations of a Substorm Brightening Aurora at L ∼ 6 by a Ground‐Based Camera and the Arase Satellite on 12 October 2017

Author

Chen, L., primary, Shiokawa, K., additional, Miyoshi, Y., additional, Oyama, S., additional, Jun, C.‐W., additional, Ogawa, Y., additional, Hosokawa, K., additional, Inaba, Y., additional, Kazama, Y., additional, Wang, S. Y., additional, Tam, S. W. Y., additional, Chang, T. F., additional, Wang, B. J., additional, Asamura, K., additional, Kasahara, S., additional, Yokota, S., additional, Hori, T., additional, Keika, K., additional, Kasaba, Y., additional, Kumamoto, A., additional, Tsuchiya, F., additional, Shoji, M., additional, Kasahara, Y., additional, Matsuoka, A., additional, Shinohara, I., additional, Imajo, S., additional, Nakamura, S., additional, and Kitahara, M., additional

Published
2022
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7. Analysis of Electron Precipitation and Ionospheric Density Enhancements Due To Hiss Using Incoherent Scatter Radar and Arase Observations

Author

Ma, Q., primary, Xu, W., additional, Sanchez, E. R., additional, Marshall, R. A., additional, Bortnik, J., additional, Reyes, P. M., additional, Varney, R. H., additional, Kaeppler, S. R., additional, Miyoshi, Y., additional, Matsuoka, A., additional, Kasahara, Y., additional, Matsuda, S., additional, Tsuchiya, F., additional, Kumamoto, A., additional, Kasahara, S., additional, Yokota, S., additional, Keika, K., additional, Hori, T., additional, Mitani, T., additional, Nakamura, S., additional, Kazama, Y., additional, Wang, S.‐Y., additional, Jun, C.‐W., additional, Shinohara, I., additional, and Tam, S. W.‐Y., additional

Published
2022
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8. First Simultaneous Observation of a Night Time Medium‐Scale Traveling Ionospheric Disturbance From the Ground and a Magnetospheric Satellite

Author

Kawai, K., Shiokawa, K., Otsuka, Y., Oyama, S., Kasaba, Y., Kasahara, Y., Tsuchiya, F., Kumamoto, A., Nakamura, S., Matsuoka, A., Imajo, S., Kazama, Y., Wang, S.‐Y., Tam, S. W. Y., Chang, T. F., Wang, B. J., Asamura, K., Kasahara, S., Yokota, S., Keika, K., Hori, T., Miyoshi, Y., Jun, C., Shoji, M., Shinohara, I., Kawai, K., Shiokawa, K., Otsuka, Y., Oyama, S., Kasaba, Y., Kasahara, Y., Tsuchiya, F., Kumamoto, A., Nakamura, S., Matsuoka, A., Imajo, S., Kazama, Y., Wang, S.‐Y., Tam, S. W. Y., Chang, T. F., Wang, B. J., Asamura, K., Kasahara, S., Yokota, S., Keika, K., Hori, T., Miyoshi, Y., Jun, C., Shoji, M., and Shinohara, I.

Abstract

Medium-scale traveling ionospheric disturbances (MSTIDs) are a phenomenon widely and frequently observed over the ionosphere from high to low latitudes. Night time MSTIDs are caused generally by the polarization electric field in the ionosphere. However, propagation of this polarization electric field to the magnetosphere has not yet been identified. Here, we report the first observation of the polarization electric field and associated density variations of a night time MSTID in the magnetosphere. The MSTID event was observed by an all-sky airglow imager at Gakona (geographical latitude: 62.39°N, geographical longitude: 214.78°E, magnetic latitude: 63.20°N), Alaska. The Arase satellite passed over the MSTID in the inner magnetosphere at 0530–0800 UT (2030–2300 LT) on November 3, 2018. This MSTID, observed in 630 nm airglow images, was propagating westward with a horizontal wavelength of ∼165 km, a north–south phase front, and a phase velocity of ∼80 m/s. The Arase satellite footprint on the ionosphere crossed the MSTID in the direction nearly perpendicular to the MSTID phase fronts. The electric field and electron density observed by the Arase satellite showed periodic variation associated with the MSTID structure with amplitudes of ∼2 mV/m and ∼150 cm−3, respectively. The electric field variations projected to the ionosphere are mainly in the east-west direction and are consistent with the direction of the polarization electric field expected from MSTID growth by E × B drift. This observation indicates that the polarization electric field associated with the MSTID in the ionosphere is projected onto the magnetosphere, causing plasma density fluctuations in the magnetosphere.

Published
2022

9. Study of an Equatorward Detachment of Auroral Arc From the Oval Using Ground‐Space Observations and the BATS‐R‐US–CIMI Model

Author

Yadav, Sneha, Shiokawa, K., Oyama, S., Inaba, Y., Takahashi, N., Seki, K., Keika, K., Chang, Tzu‐Fang, Tam, S. W. Y., Wang, B.‐J., Kazama, Y., Wang, S.‐Y., Asamura, K., Kasahara, S., Yokota, S., Hori, T., Kasaba, Y., Tsuchiya, F., Kumamoto, A., Shoji, M., Kasahara, Y., Matsuoka, A., Matsuda, S., Jun, C.‐W., Imajo, S., Miyoshi, Y., Shinohara, I., Yadav, Sneha, Shiokawa, K., Oyama, S., Inaba, Y., Takahashi, N., Seki, K., Keika, K., Chang, Tzu‐Fang, Tam, S. W. Y., Wang, B.‐J., Kazama, Y., Wang, S.‐Y., Asamura, K., Kasahara, S., Yokota, S., Hori, T., Kasaba, Y., Tsuchiya, F., Kumamoto, A., Shoji, M., Kasahara, Y., Matsuoka, A., Matsuda, S., Jun, C.‐W., Imajo, S., Miyoshi, Y., and Shinohara, I.

Abstract

We present observations of an equatorward detachment of the auroral arc from the main oval and magnetically conjugate measurements made by the Arase satellite in the inner magnetosphere. The all-sky imager at Gakona (magnetic latitude = 63.6°N), Alaska, shows the detachment of the auroral arc in both red and green lines at local midnight (∼0130–0230 MLT) on 30 March 2017. The electron density derived from the Arase in-situ observations shows that this arc occurred outside the plasmapause. At the arc crossing, the electron flux of energies ∼0.1–2 keV is found to be locally enhanced at L∼4.3–4.5. We estimated auroral intensities for both red and green lines by using the Arase low-energy (0.1–19 keV) electron flux data. The peak latitude of the estimated intensity shows reasonably good correspondence with the observed intensity mapped at the ionospheric footprints of the Arase satellite. These findings indicate that the observed arc detachment at Gakona was associated with the localized enhancement of low-energy electrons (∼0.1–2 keV) at the inner edge of the electron plasma sheet. Further, we employ the simulation results of the Community Coordinated Modeling Center (CCMC), the BATS-R-US–CIMI 3-D MHD code to understand the conditions in the inner magnetosphere around the time of detachment. Although the simulation could not reproduce the lower-energy component responsible for the arc detachment, it successfully reproduced two earthward convection events at the lower radial distance (R) (R ≤ ∼4) around the time of arc detachment and the features of enhanced convection in similarity with the observations.

Published
2022

10. Statistical Study of Approaching Strong Diffusion of Low‐Energy Electrons by Chorus and ECH Waves Based on In Situ Observations

Author

Fukizawa, M., primary, Sakanoi, T., additional, Miyoshi, Y., additional, Kazama, Y., additional, Katoh, Y., additional, Kasahara, Y., additional, Matsuda, S., additional, Kumamoto, A., additional, Tsuchiya, F., additional, Matsuoka, A., additional, Kurita, S., additional, Nakamura, S., additional, Shoji, M., additional, Teramoto, M., additional, Imajo, S., additional, Shinohara, I., additional, Wang, S.‐Y., additional, Tam, S. W.‐Y., additional, Chang, T.‐F., additional, Wang, B.‐J., additional, and Jun, C.‐W., additional

Published
2022
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11. Study of an Equatorward Detachment of Auroral Arc From the Oval Using Ground‐Space Observations and the BATS‐R‐US–CIMI Model

Author

Yadav, Sneha, primary, Shiokawa, K., additional, Oyama, S., additional, Inaba, Y., additional, Takahashi, N., additional, Seki, K., additional, Keika, K., additional, Chang, Tzu‐Fang, additional, Tam, S. W. Y., additional, Wang, B.‐J., additional, Kazama, Y., additional, Wang, S.‐Y., additional, Asamura, K., additional, Kasahara, S., additional, Yokota, S., additional, Hori, T., additional, Kasaba, Y., additional, Tsuchiya, F., additional, Kumamoto, A., additional, Shoji, M., additional, Kasahara, Y., additional, Matsuoka, A., additional, Matsuda, S., additional, Jun, C.‐W., additional, Imajo, S., additional, Miyoshi, Y., additional, and Shinohara, I., additional

Published
2021
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13. First Simultaneous Observation of a Night Time Medium‐Scale Traveling Ionospheric Disturbance From the Ground and a Magnetospheric Satellite

Author

Kawai, K., primary, Shiokawa, K., additional, Otsuka, Y., additional, Oyama, S., additional, Kasaba, Y., additional, Kasahara, Y., additional, Tsuchiya, F., additional, Kumamoto, A., additional, Nakamura, S., additional, Matsuoka, A., additional, Imajo, S., additional, Kazama, Y., additional, Wang, S.‐Y., additional, Tam, S. W. Y., additional, Chang, T. F., additional, Wang, B. J., additional, Asamura, K., additional, Kasahara, S., additional, Yokota, S., additional, Keika, K., additional, Hori, T., additional, Miyoshi, Y., additional, Jun, C., additional, Shoji, M., additional, and Shinohara, I., additional

Published
2021
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14. Investigation of small‐scale electron density irregularities observed by the Arase and Van Allen Probes satellites inside and outside the plasmasphere

Author

Thomas, N. (Neethal), Shiokawa, K. (Kazuo), Miyoshi, Y. (Yoshizumi), Kasahara, Y. (Yoshiya), Shinohara, I. (Iku), Kumamoto, A. (Atsushi), Tsuchiya, F. (Fuminori), Matsuoka, A. (Ayako), Kasahara, S. (Satoshi), Yokota, S. (Shoichiro), Keika, K. (Kunihiro), Hori, T. (Tomoaki), Asamura, K. (Kazushi), Wang, S. (Shiang‐Yu), Kazama, Y. (Yoichi), Tam, S. W. (Sunny Wing‐Yee), Chang, T. (Tzu‐Fang), Wang, B. (Bo‐Jhou), Wygant, J. (John), Breneman, A. (Aaron), and Reeves, G. (Geoffrey)

Subjects
plasmasphere, Physics::Space Physics, inner magnetosphere, electron density, small‐scale density irregularities, Arase, Van Allen Probes
Abstract

In situ electron density profiles obtained from Arase in the night magnetic local time (MLT) sector and from RBSP‐B covering all MLTs are used to study the small‐scale density irregularities present in the plasmasphere and near the plasmapause. Electron density perturbations with amplitudes >10% from background density and with time‐scales less than 30‐min are investigated here as the small‐scale density irregularities. The statistical survey of the density irregularities is carried out using nearly 2 years of density data obtained from RBSP‐B and 4 months of data from Arase satellites. The results show that density irregularities are present globally at all MLT sectors and L‐shells both inside and outside the plasmapause, with a higher occurrence at L > 4. The occurrence of density irregularities is found to be higher during disturbed geomagnetic and interplanetary conditions. The case studies presented here revealed: (1) The plasmaspheric density irregularities observed during both quiet and disturbed conditions are found to coexist with the hot plasma sheet population. (2) During quiet periods, the plasma waves in the whistler‐mode frequency range are found to be modulated by the small‐scale density irregularities, with density depletions coinciding well with the decrease in whistler intensity. Our observations suggest that different source mechanisms are responsible for the generation of density structures at different MLTs and geomagnetic conditions.

Published
2021

15. Arase Observation of Simultaneous Electron Scatterings by Upper‐Band and Lower‐Band Chorus Emissions

Author

Kazama, Y., primary, Miyoshi, Y., additional, Kojima, H., additional, Kasahara, Y., additional, Kasahara, S., additional, Usui, H., additional, Wang, B.‐J., additional, Wang, S.‐Y., additional, Tam, S. W. Y., additional, Chang, T. F., additional, Asamura, K., additional, Matsuda, S., additional, Kumamoto, A., additional, Tsuchiya, F., additional, Kasaba, Y., additional, Shoji, M., additional, Matsuoka, A., additional, Teramoto, M., additional, Takashima, T., additional, and Shinohara, I., additional

Published
2021
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16. Substorm-Associated Ionospheric Flow Fluctuations During the 27 March 2017 Magnetic Storm: SuperDARN-Arase Conjunction

Author

Shepherd, S. G., Ruohoniemi, J. M., Connors, M., Nakano, S., Kazama, Y., Wang, S. -Y., Tam, S. W. Y., Chang, T. -F., Wang, B. -J., Hori, Tomoaki, Nishitani, Nozomu, Teramoto, Mariko, Seki, Kanako, Takahashi, Naoko, Kasahara, Satoshi, Yokota, Shoichiro, Mitani, Takefumi, Takashima, Takeshi, Higashio, Nana, Matsuoka, Ayako, Asamura, Kazushi, Miyoshi, Yoshizumi, and Shinohara, Iku

Subjects
Geomagnetic storm, Physics, Geophysics, 010504 meteorology & atmospheric sciences, Flow (mathematics), Conjunction (astronomy), Substorm, General Earth and Planetary Sciences, Ionosphere, 010502 geochemistry & geophysics, 01 natural sciences, 0105 earth and related environmental sciences
Abstract

著者人数: 23名, Accepted: 2018-08-30, 資料番号: SA1180143000

Published
2018

17. Substorm-Associated Ionospheric Flow Fluctuations During the 27 March 2017 Magnetic Storm: SuperDARN-Arase Conjunction

Author

Hori, T., Nishitani, N., Shepherd, S. G., Ruohoniemi, J. M., Connors, M., Teramoto, M., Nakano, S., Seki, K., Takahashi, N., Kasahara, S., Yokota, S., Mitani, T., Takashima, T., Higashio, N., Matsuoka, A., Asamura, K., Kazama, Y., Wang, S.-Y., Tam, S. W. Y., Chang, T.-F., Wang, B.-J., Miyoshi, Y., and Shinohara, I.

Subjects
ERG, Physics::Space Physics, substorm injection, SuperDARN, Physics::Atmospheric and Oceanic Physics, Physics::Geophysics, ULF wave, ring current electron, M‐I coupling
Abstract

Super Dual Auroral Radar Network (SuperDARN) observations show that ionospheric flow fluctuations of millihertz or lower‐frequency range with horizontal velocities of a few hundred meters per second appeared in the subauroral to midlatitude region during a magnetic storm on 27 March 2017. A set of the radars have provided the first ever observations that the fluctuations propagate azimuthally both westward and eastward simultaneously, showing bifurcated phase propagation associated with substorm expansion. Concurrent observations near the conjugate site in the inner magnetosphere made by the Arase satellite provide evidence that multiple drifting clouds of electrons in the near‐Earth equatorial plane were associated with the electric field fluctuations propagating eastward in the ionosphere. We interpret this event in terms of mesoscale pressure gradients carried by drifting ring current electrons that distort field lines one after another as they drift through the inner magnetosphere, causing eastward propagating ionospheric electric field fluctuations., ファイル公開：2019-03-28

Published
2018

18. Extremely Collimated Electron Beams in the High Latitude Magnetosphere Observed by Arase

Author

Kazama, Y., primary, Kojima, H., additional, Miyoshi, Y., additional, Kasahara, Y., additional, Kasahara, S., additional, Usui, H., additional, Wang, B.‐J., additional, Wang, S.‐Y., additional, Tam, S. W. Y., additional, Chang, T.‐F., additional, Asamura, K., additional, Kasaba, Y., additional, Matsuda, S., additional, Shoji, M., additional, Matsuoka, A., additional, Teramoto, M., additional, Takashima, T., additional, and Shinohara, I., additional

Published
2021
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19. Assessment of Sensor Technologies for Advanced Reactors

Author

Korsah, Kofi, primary, Ramuhalli, Pradeep, additional, Vlim, R., additional, Kisner, Roger A., additional, Britton, Jr, Charles L., additional, Wootan, D. W., additional, Anheier, Jr, N. C., additional, Diaz, A. A., additional, Hirt, E. H., additional, Chien, H. T., additional, Sheen, S., additional, Bakhtiari, Sasan, additional, Gopalsami, S., additional, Heifetz, A., additional, Tam, S. W., additional, Park, Y., additional, Upadhyaya, B. R., additional, and Stanford, A., additional

Published
2016
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21. Pitch‐Angle Scattering of Inner Magnetospheric Electrons Caused by ECH Waves Obtained With the Arase Satellite

Author

Fukizawa, M., primary, Sakanoi, T., additional, Miyoshi, Y., additional, Kazama, Y., additional, Katoh, Y., additional, Kasahara, Y., additional, Matsuda, S., additional, Matsuoka, A., additional, Kurita, S., additional, Shoji, M., additional, Teramoto, M., additional, Imajo, S., additional, Sinohara, I., additional, Wang, S.‐Y., additional, Tam, S. W.‐Y., additional, Chang, T.‐F., additional, Wang, B.‐J., additional, and Jun, C.‐W., additional

Published
2020
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22. Arase Observation of the Source Region of Auroral Arcs and Diffuse Auroras in the Inner Magnetosphere

Author

Shiokawa, K., primary, Nosé, M., additional, Imajo, S., additional, Tanaka, Y.‐M., additional, Miyoshi, Y., additional, Hosokawa, K., additional, Connors, M., additional, Engebretson, M., additional, Kazama, Y., additional, Wang, S.‐Y., additional, Tam, S. W. Y., additional, Chang, Tzu‐Fang, additional, Wang, Bo‐Jhou, additional, Asamura, K., additional, Kasahara, S., additional, Yokota, S., additional, Hori, T., additional, Keika, K., additional, Kasaba, Y., additional, Shoji, M., additional, Kasahara, Y., additional, Matsuoka, A., additional, and Shinohara, I., additional

Published
2020
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25. Plasma and field observations in the magnetospheric source region of a stable auroral red (SAR) arc by the Arase satellite on 28 March 2017

Author

Inaba, Y. (Yudai), Shiokawa, K. (Kazuo), Oyama, S. (Shin‐ichiro), Otsuka, Y. (Yuichi), Oksanen, A. (Arto), Shinbori, A. (Atsuki), Gololobov, A. Y. (Artem Yu), Miyoshi, Y. (Yoshizumi), Kazama, Y. (Yoichi), Wang, S. (Shiang‐Yu), Tam, S. W. (Sunny W. Y.), Chang, T. (Tzu‐Fang), Wang, B. (Bo‐Jhou), Yokota, S. (Shoichiro), Kasahara, S. (Satoshi), Keika, K. (Kunihiro), Hori, T. (Tomoaki), Matsuoka, A. (Ayako), Kasahara, Y. (Yoshiya), Kumamoto, A. (Atsushi), Kasaba, Y. (Yasumasa), Tsuchiya, F. (Fuminori), Shoji, M. (Masafumi), Shinohara, I. (Iku), Stolle, C. (Claudia), Inaba, Y. (Yudai), Shiokawa, K. (Kazuo), Oyama, S. (Shin‐ichiro), Otsuka, Y. (Yuichi), Oksanen, A. (Arto), Shinbori, A. (Atsuki), Gololobov, A. Y. (Artem Yu), Miyoshi, Y. (Yoshizumi), Kazama, Y. (Yoichi), Wang, S. (Shiang‐Yu), Tam, S. W. (Sunny W. Y.), Chang, T. (Tzu‐Fang), Wang, B. (Bo‐Jhou), Yokota, S. (Shoichiro), Kasahara, S. (Satoshi), Keika, K. (Kunihiro), Hori, T. (Tomoaki), Matsuoka, A. (Ayako), Kasahara, Y. (Yoshiya), Kumamoto, A. (Atsushi), Kasaba, Y. (Yasumasa), Tsuchiya, F. (Fuminori), Shoji, M. (Masafumi), Shinohara, I. (Iku), and Stolle, C. (Claudia)

Abstract

A stable auroral red (SAR) arc is an aurora with a dominant 630 nm emission at subauroral latitudes. SAR arcs have been considered to occur due to the spatial overlap between the plasmasphere and the ring‐current ions. In the overlap region, plasmaspheric electrons are heated by ring‐current ions or plasma waves, and their energy is then transferred down to the ionosphere where it causes oxygen red emission. However, there have been no study conducted so far that quantitatively examined plasma and electromagnetic fields in the magnetosphere associated with SAR arc. In this paper, we report the first quantitative evaluation of conjugate measurements of a SAR arc observed at 2204 UT on 28 March 2017 and investigate its source region using an all‐sky imager at Nyrölä (magnetic latitude: 59.4°N), Finland, and the Arase satellite. The Arase observation shows that the SAR arc appeared in the overlap region between a plasmaspheric plume and the ring‐current ions and that electromagnetic ion cyclotron waves and kinetic Alfven waves were not observed above the SAR arc. The SAR arc was located at the ionospheric trough minimum identified from a total electron content map obtained by the GNSS receiver network. The Swarm satellite flying in the ionosphere also passed the SAR arc at ~2320 UT and observed a decrease in electron density and an increase in electron temperature during the SAR‐arc crossing. These observations suggest that the heating of plasmaspheric electrons via Coulomb collision with ring‐current ions is the most plausible mechanism for the SAR‐arc generation.

Published
2020

30. Comparison of the Effects of Wave-Particle Interactions and the Kinetic Suprathermal Electron Population on the Acceleration of the Solar Wind

Author

Tam, S. W. Y and Chang, T

Subjects
Solar Physics
Abstract

Kinetic effects due to wave-particle interactions and suprathermal electrons have been suggested in the literature as possible solar wind acceleration mechanisms. Ion cyclotron resonant heating, in particular, has been associated with some qualitative features observed in the solar wind. In terms of solar wind acceleration, however, it is interesting to compare the kinetic effects of suprathermal electrons with those due to the wave-particle interactions. The combined effects of the two acceleration mechanisms on the fast solar wind have been studied by Tam and Chang (1999a,b). In this study. we investigate the role of the suprathermal electron population in the acceleration of the solar wind. Our model follows the global kinetic evolution of the fast solar wind under the influence of ion cyclotron resonant heating, while taking into account Coulomb collisions, and the ambipolar electric field that is consistent with the particle distributions themselves. The kinetic effects due to the suprathermal electrons, which we define to be the tail of the electron distributions, can be included in the model as an option. By comparing the results with and without the inclusion of the suprathermal electron effects, we determine the relative importance of suprathermal electrons and wave-particle interactions in driving the solar wind. We find that although suprathermal electrons enhance the ambipolar electric potential in the solar wind considerably, their overall influence as an acceleration mechanism is relatively insignificant in a wave-driven solar wind.

Published
2002
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31. Density Depletions Associated With Enhancements of Electron Cyclotron Harmonic Emissions: An ERG Observation

Author

Usui, H., Wang, B. -J., Wang, S. -Y., Tam, S. W. Y., Chang, T. -F., Ho, P. T. P., Shoji, Masafumi, Kazama, Yoichi, Kojima, Hirotsugu, Miyoshi, Yoshizumi, Kasahara, Yoshiya, Asamura, Kazushi, Kumamoto, Atsushi, Tsuchiya, Fuminori, Kasaba, Yasumasa, Matsuda, Shoya, Matsuoka, Ayako, Teramoto, Mariko, Takashima, Takeshi, and Shinohara, Iku

Subjects
Physics, 010504 meteorology & atmospheric sciences, Cyclotron, Electron, 010502 geochemistry & geophysics, 01 natural sciences, law.invention, Geophysics, law, Harmonic, General Earth and Planetary Sciences, Atomic physics, Erg, 0105 earth and related environmental sciences
Abstract

著者人数: 20名, Accepted: 2018-09-18, 資料番号: SA1180144000

Published
2018
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32. Density Depletions Associated With Enhancements of Electron Cyclotron Harmonic Emissions: An ERG Observation

Author

Kazama, Y., primary, Kojima, H., additional, Miyoshi, Y., additional, Kasahara, Y., additional, Usui, H., additional, Wang, B.‐J., additional, Wang, S.‐Y., additional, Tam, S. W. Y., additional, Chang, T.‐F., additional, Ho, P. T. P., additional, Asamura, K., additional, Kumamoto, A., additional, Tsuchiya, F., additional, Kasaba, Y., additional, Matsuda, S., additional, Shoji, M., additional, Matsuoka, A., additional, Teramoto, M., additional, Takashima, T., additional, and Shinohara, I., additional

Published
2018
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33. Determination of the surface potential in thin-film transistors from C-V measurements.

Author

Migliorato, P., Tam, S. W.-B., Lui, O. K. B., and Shimoda, T.

Subjects
*THIN film transistors, *ELECTRIC capacity, *ELECTRONICS
Abstract

In this article we present a method for the determination of the gate voltage versus surface potential (V[sub GS]-ψ[sub S]) relationship in thin-film transistors (TFTs), from low frequency capacitance-voltage (C-V) characteristics. This information is very important for device design, process characterization, and modeling of TFTs and provides the basis for extracting the gap density of states. The accuracy of the method is demonstrated by applying it to the analysis of C-V data generated by two-dimensional simulations. Its application to laser recrystallized polysilicon TFTs is presented. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2001
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34. Method for the determination of bulk and interface density of states in thin-film transistors.

Author

Lui, O. K. B., Tam, S. W.-B., Migliorato, P., and Shimoda, T.

Subjects
*THIN film transistors, *KIRKENDALL effect, *ELECTRONICS
Abstract

In this article we present a method for the accurate determination of interface and bulk density of states (DOS) in thin-film transistors (TFTs), based on the combined analysis of transfer (I[sub D]-V[sub GS]) and capacitance-voltage characteristics. This analysis has achieved a number of results, eliminating sources of inaccuracies that are known to be present in other methods. A procedure for the determination of the electron and hole flatband conductances and bulk Fermi energy is demonstrated. A recursive procedure is employed to extract the bulk DOS directly from Poisson's equation. The advantages of this method are the greater immunity to noise from the original data, the use of the complete Fermi function (no 0 K approximation), and the applicability to thin active layers. This method yields the interface state density spectrum as well as the bulk DOS. This information is very important for device design, process characterization, and modeling of TFTs. © 2001! American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2001
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37. Stability and characterization of CNT nanofluids using polyvinyl alcohol dispersant

Author

Tam, S. W., Walvekar, Rashmi Gangasa, Rashidi, Saba, Abdullah, Luqman Chuah, Siddiqui, Mohammad Khalid, Tam, S. W., Walvekar, Rashmi Gangasa, Rashidi, Saba, Abdullah, Luqman Chuah, and Siddiqui, Mohammad Khalid

Abstract

In this research, CNT-water nanofluids are synthesized using polyvinyl alcohol (PVA) dispersant where each of the CNT concentration ranging from 0.01 to 0.1 wt% is tested with 0.25 to 3.00 wt% of PVA to optimize the dispersion and stability of nanofluids. The nanofluids are sonicated for 4 hours using ultrasonic water bath and the stability is analyzed using UV-Vis spectrophotometer. The dispersion state of the CNT-water nanofluid is further examined using optical microscope. The stable nanofluids of each CNT concentration identified were then tested for their thermo-physical properties such as thermal conductivity and viscosity with respect to temperature ranging from 25 to 70 °C. The results revealed that 0.5 to 1.5 wt% of PVA dispersant give the optimum stability to the entire range of CNT concentration studied. It was found that the thermal conductivity enhancement of CNT-water nanofluid stabilized by PVA increased non-linearly with temperature. Although PVA suppressed the thermal conductivity of water, the addition of CNT is able to surpass its effect and the results showed that there is approximately 1 to 44 % enhancement for the range of CNT concentration and temperature studied. It was also observed that the viscosity for 1.5 wt% of PVA aqueous solution at 25 °C is approximately 7.5 mPa.s, which is significantly greater than water. However, the presence of CNT nanoparticles is able to reduce the viscosity of its respective optimum PVA solution by 2 to 6% for the entire range of CNT concentrations investigated, showcasing self-lubrication effect of CNT. Moreover, the viscosity of the nanofluids decreases significantly with increasing temperature.

Published
2016

38. Quantum key distribution over multicore fiber

Author

Dynes, J. F., primary, Kindness, S. J., additional, Tam, S. W.-B., additional, Plews, A., additional, Sharpe, A. W., additional, Lucamarini, M., additional, Fröhlich, B., additional, Yuan, Z. L., additional, Penty, R. V., additional, and Shields, A. J., additional

Published
2016
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